Ravie LakshmananJun 08, 2026Cyber Espionage / Malware
A China-nexus cyber espionage group has been observed deploying a BSD variant of a known backdoor called BRICKSTORM, as well as two other malware families codenamed PLENET (aka GRIMBOLT) and AGENTPSD to target Linux systems.
The activity has been attributed by Volexity to a threat cluster it tracks as VerdantBamboo, which it said overlaps with hacking groups known as Clay Typhoon (Microsoft), UNC5221 (Google), and Warp Panda (CrowdStrike).
The cybersecurity company said it discovered the intrusion during an incident response engagement in September 2025, when it emerged that the adversary had compromised an unnamed victim's Egnyte Storage Sync system by exploiting a local privilege escalation flaw to deploy BRICKSTORM. The issue was addressed in Storage Sync version 13.13, released in March 2026.
"The appliance had periodically been accessed by VerdantBamboo via IP addresses assigned through the victim organization's web SSL VPN," researchers Damien Cash, Paul Rascagneres, Steven Adair, and Tom Lancaster said in a technical report published last week.
