Affected Systems
Microsoft Bing search users seeking Claude AI desktop app. Malicious Claude Artifact hosted on legitimate claude.ai domain (removed by Anthropic). At least 29 organizations compromised July 21-22, 2026. Installer (ClaudeDesktop.exe) sideloads SectopRAT (ArechClient2) info-stealer via DLL hijacking.
Exploitation Status
Active exploitation confirmed. Campaign named FakeAgent compromised 29+ organizations between July 21-22, 2026. Malicious artifact downloaded 7,100 times before removal. SectopRAT distributed via multiple vectors including CastleLoader and ClickFix attacks.
Business Impact
SectopRAT is a mature info-stealer (active since 2019) with HVNC capabilities enabling full remote control. Targets passwords, credit cards, browser data, FTP credentials, messaging apps (Discord, Telegram), Steam, and VPN products. Campaign abuses trusted claude.ai domain and Bing sponsored search results to bypass user skepticism. Anti-analysis features (VMProtect, VM detection, shader timing checks) complicate detection. C2 infrastructure uses EtherHiding via Ethereum BNB Smart Chain for resilience.
Urgency
🔴 Immediate
Recommended Actions
- Block known malicious domains linked to campaign (10 domains registered to same email since December 2025; IOCs available from Huntress report).
- Hunt for ClaudeDesktop.exe and DockerDesktop.exe executables, libcef.dll sideloading, and scheduled tasks created by DockerDesktop.exe across endpoints.
- Monitor for SectopRAT/ArechClient2 indicators: Ethereum BNB Smart Chain C2 lookups, HVNC traffic patterns, and exfiltration of browser/credential data.
- Enforce policy blocking software downloads from search ads; educate users to download only from official vendor sites (anthropic.com for Claude—no desktop app exists as of July 2026).
- Review EDR/SIEM rules for DLL sideloading detection and VMProtect-packed executables; test coverage against this infection chain.