There's new malware toolkit that uses stegaography to hide in images:
For the past two months, a new exploit kit has been serving malicious code hidden in the pixels of banner ads via a malvertising campaign that has been active on several high profile websites.
Discovered by security researchers from ESET, this new exploit kit is named Stegano, from the word steganography, which is a technique of hiding content inside other files.
In this particular scenario, malvertising campaign operators hid malicious code inside PNG images used for banner ads.
The crooks took a PNG image and altered the transparency value of several pixels. They then packed the modified image as an ad, for which they bought ad displays on several high-profile websites.