huntrule

Linux capsh Shell Execution via Shell-Spawn Command Line Ending With " --"

Alerts on Linux executions of /capsh with a command line ending in " --", consistent with shell invocation attempts.

FreeReviewedSigma · High · v3
Product
linux
Category
process_creation
Author
Li Ling, Andy Parkidomo, Robert Rakowski, Blake Hartstein (Bloomberg L.P.) (SigmaHQ), DRL 1.1
Published
2024-09-02
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Execution

  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 flags Linux process executions where the binary path ends with "/capsh" and the command line ends with " --", indicating an attempt to use capsh to spawn a shell. Attackers may leverage capsh to break out of restricted environments or gain interactive command execution. The detection relies on process creation telemetry, specifically the process image path and the full command line.

Reporting behind it

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Changelog

v3
  1. v3
    Candidate ingested via manual entry.2026-07-31
  2. v2
    Candidate ingested via manual entry.2026-07-31
  3. 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.