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Chaos ransomware's msaRAT: Living off the browser to build a covert C2 channel

· Published 23/07/2026 13:57

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Essential information

Published
23/07/2026 13:57
Modified
Source / Author
AlienVault
Confidence
100/100
Report type(s)
threat-report
Labels / Tags
browser hijacking chrome devtools protocol cloudflare workers covert tunneling msarat ransomware-as-a-service rust-based rat twilio turn webrtc
Related entities
2 indicators, 2 observables, 1 intrusion sets (apt), 20 techniques (mitre), 1 malware

Description

Cisco Talos discovered msaRAT, a new Rust-based remote access trojan attributed to the Chaos ransomware group. This sophisticated RAT never directly touches the network, instead controlling command-and-control communications exclusively through Chrome DevTools Protocol (CDP). It manipulates browsers via CDP, performs signaling with , and establishes WebRTC DataChannels using Twilio TURN as a relay. The infection chain begins with downloading an MSI file containing the RAT payload. msaRAT hijacks Chrome or Edge browsers in headless mode, injects JavaScript code, and establishes encrypted C2 communications through WebRTC. This design makes all external communications appear to originate from legitimate browser processes, effectively hiding C2 traffic within normal web activity and evading detection by firewalls and network monitoring tools.

External references