huntrule

Webserver Alerts for libredtail-http User-Agent HTTP Requests

Alerts on web requests carrying the "libredtail-http" User-Agent, indicating likely automated malicious probing.

FreeReviewedSigma · Medium · v5
Category
webserver
Author
Marco Pedrinazzi (@pedrinazziM) (InTheCyber) (SigmaHQ), DRL 1.1
Published
2026-04-30
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Initial Access

  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 inbound web requests where the HTTP User-Agent is exactly "libredtail-http". Attackers and automated scanners may use this distinctive string as part of malicious probing and exploitation chains, including cryptocurrency miner deployment. The detection relies on webserver logs that capture the client User-Agent field for each HTTP request.

Reporting behind it

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Possible TP-Link Command Injection via WlanNetworkRpm Endpoint (via webserver)
Webserver Alerts for libredtail-http User-Agent HTTP Requests
Pivot detection · T1190 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. 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.