Security News > 2021 > May > Chinese Hackers Started Covering Tracks Days Before Public Exposure of Operations

One of the Chinese threat actors targeting Pulse Secure VPN appliances via a recently disclosed vulnerability has been attempting to cover its tracks by removing its webshells from victim networks, FireEye reports.

Tracked as CVE-2021-22893, the vulnerability was made public in late April, after security researchers discovered that threat actors had already been exploiting it in attacks targeting organizations in the defense, financial, government, high tech, and transportation sectors in the U.S. and Europe.

At the time, FireEye revealed that at least two Chinese threat actors believed to be state-sponsored - UNC2630 and UNC2717 - had been exploiting the vulnerability for initial compromise.

FireEye says it has since identified four other malware families used in these attacks, namely BLOODMINE, BLOODBANK, CLEANPULSE, and RAPIDPULSE. On the other hand, just days before FireEye made its findings public in April, UNC2630 was spotted removing its webshells from dozens of devices.

"It is unusual for Chinese espionage actors to remove a large number of backdoors across several victim environments on or around the time of public disclosure. This action displays an interesting concern for operational security and a sensitivity to publicity," FireEye notes.

In a Thursday update to its alert on the targeting of Pulse Secure VPN appliances, the U.S. Cybersecurity and Infrastructure Security Agency also noted that one of the identified threat actors has started cleanup operations, in an attempt to hide their tracks.

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