huntrule

Proxy Detection: Cobalt Strike Malleable C2 Profile HTTP URI/User-Agent/Method Patterns

Flags proxy HTTP requests whose URI, method, User-Agent, host, and cookie fragments match known Cobalt Strike malleable profile patterns.

FreeReviewedSigma · High · v2
Category
proxy
Author
Markus Neis, Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2024-02-15
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

C2

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule identifies HTTP proxy traffic matching specific request patterns associated with Cobalt Strike malleable C2 profiles, including particular URIs, User-Agent strings, HTTP methods, destination hosts, and (in one case) cookie suffixes. Attackers use malleable profiles to shape command-and-control traffic to blend in with legitimate web requests, making pattern-based detection valuable. The detection relies on proxy log fields such as c-uri, cs-host, cs-method, c-useragent, and cs-cookie to match the defined combinations.

Reporting behind it

Related detections9 linkedT1071.001 — drag to rearrange
Malicious HarborWatch RAT Command and Control Beacon by User Agent (via proxy)
Suspicious UAT-10608 Credential Harvesting C2 Beacon via HTTP
Malicious BadIIS C2 Communication via lwxatisme User-Agent
Possible PS1Bot C2 Beacon With Drive Serial URI Pattern (via proxy)
Suspicious WarmCookie C2 Beacon With Fixed Firefox User-Agent
Malicious Renamed Python Interpreter Executing nvidia.py RAT
Malicious Self-Signed TLS Certificate With Exploit Subject via Zeek X509
Suspicious Network Connection From wabmig.exe (Turian Injection)
Suspicious wmicodegen.dll Sideload by inetinfo.exe (UAT-8099 Cobalt Strike)
Proxy Detection: Cobalt Strike Malleable C2 Profile HTTP URI/User-Agent/Method Patterns
Pivot detection · T1071.001 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.