Malware Makers Get Creative, But Still Leave Clues Behind
A new variant of the DOUBLECUP malware has made headlines in cybersecurity circles for its use of what appears to be steganography – hiding malicious code within an image file. However, upon closer inspection, it turns out that this particular strain doesn’t actually employ real steganography techniques after all. Instead, it relies on a clever trick to remain undetected by security software.
The malware in question uses a PNG image as its payload container. At first glance, it seems like the malicious code is hidden within the image’s pixels or metadata – but that’s not quite true. A closer look reveals that the PowerShell script is simply appended after the end of the PNG file. This may seem like a clever way to avoid detection, but security experts are already finding ways to extract and analyze the malware.
The real interesting part of this story lies in how the malware makers chose to hide their code. They didn’t use any complex encoding or encryption techniques – instead, they took advantage of a quirk in Windows’ handling of text files. The PowerShell script starts with the characters 0x0D 0x0A, which is the carriage return and newline sequence used to terminate lines of text in Windows. This means that security software can use the built-in FINDSTR command (similar to Unix’s grep) to locate the unique identifier of the malware and extract it from the image file.
While this may seem like a clever trick on the part of the malware makers, it’s not entirely effective. Security experts are already finding ways to detect and analyze the malware, and it won’t take long for security software to be updated to include detection signatures for this particular variant. The takeaway here is that while malware makers are getting more creative in their attempts to evade detection, they’re still leaving clues behind – and it’s only a matter of time before those clues are used to bring them down.
For users, the most important thing to take away from this story is the importance of staying vigilant when it comes to image files. While this particular variant may not be as sophisticated as some other malware, it’s still a reminder that even seemingly innocuous files can contain malicious code. When in doubt, it’s always best to err on the side of caution and run any suspicious files through security software before opening them.
Source: SANS ISC — 2026-08-24