huntrule

Exchange ProxyLogon activity: IIS POST SetObject Reset VirtualDirectory requests

Alerts on successful POSTs to ECP DDIService SetObject resetting a VirtualDirectory with a '$' username suffix.

FreeReviewedSigma · Critical · v5
Category
webserver
Author
frack113 (SigmaHQ), DRL 1.1
Published
2021-08-10
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 matches HTTP POST requests returning status 200 that target the /ecp/DDI/DDIService.svc/SetObject endpoint with query parameters indicating schema=Reset and VirtualDirectory. It also looks for usernames ending with '$', which can be associated with certain automated behaviors during exploitation attempts. Telemetry relies on webserver HTTP fields including request method, status code, URI stem, URI query contents, and authenticated username where available.

Reporting behind it

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Exchange ProxyLogon activity: IIS POST SetObject Reset VirtualDirectory 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.