They used steganography, a relatively rarely deployed technique for hiding malicious code or data behind image files or other innocuous-looking files. In its analysis of Operation Shady RAT, Symantec found rigged images--everything from images of a pastoral waterside scene to a suggestive photo of a woman in a hat--that were masking commands ordering the infected machines to phone home to the command-and-control (C&C) server.
The commands are invisible to the human eye because the bits in the image are actually made up of those commands. They're "mathematically built into the data representing the image," according to Symantec researchers in a recent blog post that includes examples of the images its researchers found.
Operation Shady RAT is a massive advanced persistent threat (APT)-type attack campaign that has been ongoing worldwide for five years and has stolen intellectual property from 70 government agencies, international corporations, nonprofits, and others in 14 countries. It was revealed last week by McAfee, which conducted an in-depth study of one of the C&C servers used in the attack.
Remaining under the radar is crucial for APT attackers. The Shady RAT attackers also deployed a tool called HTran that helps disguise their locations. Joe Stewart, director of malware research for Dell SecureWorks' counter threat unit research team, recently discovered a pattern in APT malware in which many of these attackers use HTran--including the Operation Shady RAT attackers, he said.
At a full-day virtual event, InformationWeek and Dark Reading editors will talk with security experts about the causes and mistakes that lead to security breaches, both from the technology perspective and from the people perspective. It happens Aug. 25. Register now.