Chrome encryption bypass discovered: New malware steals passwords and cookies

Vojtěch Krejsa, the threat researcher at Gen who first flagged the stealer, calls VoidStealer’s bypass non-noisy. “The bypass requires neither privilege escalation nor code injection, making it a stealthier approach compared to alternative ABE bypass methods,” he said in a blog post.

Chasing the master key

An ABE bypass revolves around a critical piece of material, the “v20_master-key.” This key is what ultimately unlocks stored browser secrets, including cookies, passwords, and tokens, once the browser has verified the request. In theory, ABE keeps this key tightly guarded, ensuring it’s never exposed in a way that malware can easily access it.However, in practice, that key still has to exist in plaintext at runtime, if only briefly, for Chrome to do its job.

Earlier bypass techniques found ways to go after decryption, some relying on process injection that involved slipping malicious code into Chrome to invoke a legitimate decryption routine. Others used memory dumping or remote debugging, scanning large chunks of process memory to locate decrypted data. More advanced approaches abused Chrome’s elevation service or COM interfaces to trick the browser into handing over decrypted material.

About Author

AndyC

Andy Curtis is an award-winning security consultant, researcher and public speaker. He has been working in the computer security industry since the early 1990s, having been employed by state and federal government, leading healthcare and banking providers across three continents. He has given talks about computer security for some of the world’s largest companies, worked with law enforcement agencies on investigations into hacking groups, and is a regular voice on TV and radio explaining IT security threats.

See author's posts