Security Experts:

Image Stealing Malware Could Be Early Test of Information Theft

Recently discovered malware targeting image files could likely be the first stage of a larger attack, anti-malware experts claim. A new Trojan, which arrived out of the blue earlier this month, was found targeting only two types of data; and if the harvest is fruitful, it ships the bounty off to a remote server.

Earlier this month, Trend Micro reported that a Trojan was circulating online that had some unique features. Namely, it searched an infected system for image files (JPG & JPEG), in addition to Windows memory dump files (*.DMP). The malware is programmed to search C:, D:, and E: drives for the files, and if discovered they are copied back to C: before being delivered via FTP to a remote server. Incidentally, only the first 20,000 files are shipped off.

Trend Micro seemed to discount the threat, mentioning that it could pose a new level of risk to users who use images to store valuable information instead of text. However, other than that warning and observation, there was little more to note. Trend named the malware PixSteal and added it to their detection network.

McAfee on the other hand, thinks that there is more to image thief than first imagined. The FTP server that was hosting the harvested data was shutdown on Tuesday, leading them to examine the code further.

“We suspect this malware is in its first stage of development for information theft, and we expect it to return as a more sophisticated attack," McAfee’s Niranjan Jayanand noted. "The stolen image files could be used for blackmailing the victims and demanding a ransom...We also suspect the attackers would like to learn about vulnerabilities on the victims’ machines; perhaps that is why they are looking for .dmp files, which carry data 'dumped' from a program’s memory space. They are often created when a program has an error in coding and crashes.”

However, it could also be that the malware’s authors made a mistake. Instead of looking for DMP files, they may have intended to harvest another image type: Bitmaps or BMP. If this isn’t the case though, then administrators and users need to be mindful.

“This malware can evolve with more sophisticated code and cause more harm. Since 2008, we have seen image files carrying embedded image files within," McAfee warned. "Malware authors sometimes hide their commands behind an image file using steganography. We advise our customers to pay extra attention when they save any file type while online and to keep their antimalware software updated.”

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Steve Ragan is a security reporter and contributor for SecurityWeek. Prior to joining the journalism world in 2005, he spent 15 years as a freelance IT contractor focused on endpoint security and security training.