An updated version of a malware loader known as BLISTER is being used as part of SocGholish infection chains to distribute an open-source command-and-control (C2) framework called Mythic.
"New BLISTER update includes keying feature that allows for precise targeting of victim networks and lowers exposure within VM/sandbox environments," Elastic Security Labs researchers Salim Bitam and Daniel Stepanic said in a technical report published late last month.
BLISTER was first uncovered by the company in December 2021 acting as a conduit to distribute Cobalt Strike and BitRAT payloads on compromised systems.
In these attacks, BLISTER is embedded within a legitimate VLC Media Player library in an attempt to get around security software and infiltrate victim environments.
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Both SocGholish and BLISTER have been used in tandem as part of several campaigns, with the latter used as a second-stage loader to distribute Cobalt Strike and LockBit ransomware, as evidenced by Red Canary and Trend Micro in early 2022.
A closer analysis of the malware shows that it's being actively maintained, with the malware authors incorporating a slew of techniques to fly under the radar and complicate analysis.
"BLISTER is a loader that continues to stay under the radar, actively being used to load a variety of malware including clipbankers, information stealers, trojans, ransomware, and shellcode," Elastic noted in April 2023.