huntrule

Microsoft Exchange exploitation attempt via suspicious POST requests in web server logs

Flags POST traffic to Exchange OWA/ECP-related URLs with specific client and user-agent indicators consistent with exploitation attempts.

FreeReviewedSigma · High · v5
Category
webserver
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2021-03-03
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 flags HTTP POST activity against Microsoft Exchange-related paths (such as /owa/ and /ecp/) combined with specific user agents and query components. Attackers may use crafted requests to exploit exposed Exchange endpoints for initial access or remote exploitation. The detection relies on web server request telemetry, matching the HTTP method, URI query/content patterns, and exact or listed User-Agent strings.

Reporting behind it

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Microsoft Exchange exploitation attempt via suspicious POST requests in web server logs
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.