A new wave of North Korea’s ‘Contagious Interview’ campaign is currently targeting unsuspecting job seekers with malicious packages. These packages infect developers’ devices with infostealers and backdoors, representing a very significant supply chain security threat. The packages were discovered by Socket Threat Research, which reports they load the BeaverTail info-stealer on victims’ machines. They also deploy InvisibleFerret, a backdoor that has been well-documented and associated with state-sponsored North Korean hacking actors.
Victims, who are typically software engineers and developers, are led to download these packages by North Korean operatives.
These operatives pose as legitimate recruiters on professional networking sites like LinkedIn, requesting job candidates to work on a test project. Posing as recruiters, they send coding “assignments” to developers and job seekers via many different online platforms. They often pressure candidates to run the code outside containerized environments while they are actively screen-sharing with them.
The assignments are hosted on Bitbucket and are cleverly disguised as legitimate tests for a potential job opportunity. In reality, they trigger a complex infection chain that drops multiple different payloads on the target’s personal computer. The first stage is the HexEval Loader, which is hidden in the npm packages and fingerprints the host computer. BeaverTail is a multi-platform info-stealer and malware loader that is designed to steal very valuable browser data.
BeaverTail steals cookies and cryptocurrency wallets, and then it proceeds to load the third stage, the InvisibleFerret backdoor. InvisibleFerret is a cross-platform persistent backdoor that is delivered to the victim as a compressed ZIP file. It gives the attackers deeper, ongoing access to the victim’s system with a wide variety of remote control capabilities. The attackers have also dropped a cross-platform keylogger tool that hooks into low-level input events for real-time surveillance.
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