Sigma rule: ProxyLogon Reset Virtual Directories Based On IIS Log

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-fbd49815a2b1, updated 2023-05-08T00:00:00.000Z.

Rule

Title
ProxyLogon Reset Virtual Directories Based On IIS Log
Status
test
Level
critical
Author
frack113
Date
2021-08-10
Modified
2023-05-08
File
rules-emerging-threats/2021/Exploits/CVE-2021-26858/web_cve_2021_26858_iis_rce.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

When exploiting this vulnerability with CVE-2021-26858, an SSRF attack is used to manipulate virtual directories

Log source

category
webserver
definition
Requirements: The POST request body data must be collected in order to make use of this detection

Detection

selection:
    cs-method: 'POST'
    sc-status: 200
    cs-uri-stem: '/ecp/DDI/DDIService.svc/SetObject'
    cs-uri-query|contains|all:
        - 'schema=Reset'
        - 'VirtualDirectory'
    cs-username|endswith: '$'
keywords:
    '|all':
        - 'POST'
        - 200
        - '/ecp/DDI/DDIService.svc/SetObject'
        - 'schema=Reset'
        - 'VirtualDirectory'
        - '$'
condition: selection or keywords

False positives (as the rule lists them)

  • Unlikely

Tags

  • cve.2021-26858
  • detection.emerging-threats
  • attack.initial-access
  • attack.t1190

CVEs this rule names

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-26858/web_cve_2021_26858_iis_rce.yml

Sources and licences

  • SigmaHQ

    "ProxyLogon Reset Virtual Directories Based On IIS Log" by frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-26858/web_cve_2021_26858_iis_rce.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: ProxyLogon Reset Virtual Directories Based On IIS Log",
entity page, dataset version ref-fbd49815a2b1, updated 2023-05-08T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/effee1f6-a932-4297-a81f-acb44064fa3a (accessed 2026-11-03).
Underlying source: SigmaHQ rule effee1f6-a932-4297-a81f-acb44064fa3a, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.