Ars Technica used in malware campaign with never-before-seen obfuscation

Ars Technica was recently used to serve second-stage malware in a campaign that used a never-before-seen attack chain to cleverly cover its tracks, researchers from security firm Mandiant reported Tuesday.

A benign image of a pizza was uploaded to a third-party website and was then linked with a URL pasted into the “about” page of a registered Ars user. Buried in that URL was a string of characters that appeared to be random—but were actually a payload. The campaign also targeted the video-sharing site Vimeo, where a benign video was uploaded and a malicious string was included in the video description. The string was generated using a technique known as Base 64 encoding. Base 64 converts text into a printable ASCII string format to represent binary data. Devices already infected with the first-stage malware used in the campaign automatically retrieved these strings and installed the second stage.

“This is a different and novel way we’re seeing abuse that can be pretty hard to detect,” Mandiant researcher Yash Gupta said in an interview. “This is something in malware we have not typically seen. It’s pretty interesting for us and something we wanted to call out.”