huntrule

Windows Exchange Management: Set-OabVirtualDirectory ExternalUrl to script content

Detects Exchange Management changes to OAB ExternalUrl containing script indicators and Page_Load.

FreeReviewedSigma · High · v2
Product
windows
Service
msexchange-management
Author
Jose Rodriguez @Cyb3rPandaH (SigmaHQ), DRL 1.1
Published
2021-03-15
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Persistence

  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 Exchange Management activity where Set-OabVirtualDirectory is used to modify the ExternalUrl property with script-related content, including Page_Load and script. Attackers may use this to persist malicious behavior by pointing Exchange-controlled components to executable script logic. The detection relies on msexchange-management telemetry captured as keyword matches across the command/output text.

Reporting behind it

Related detections9 linkedT1505.003 — drag to rearrange
Suspicious IIS Worker Process Spawning Command or Scripting Interpreter via SharePoint ToolShell Exploitation (via process_creation)
Suspicious Weaver Ant In-Memory Web Shell Marker in Web Request (via webserver)
Malicious Web Server Process Spawning Command Interpreter via Web Shell (via process_creation)
Malicious Web Shell Written to SharePoint LAYOUTS Directory by Worker Process (via file_event)
Malicious IIS Worker Process Spawning Command Shell for Webshell Reconnaissance (via process_creation)
Malicious Command Shell Spawned by SQL Server via Process Creation (via process_creation)
Suspicious PHP Webshell Access with Hardcoded Key
Suspicious IIS Configuration Reconnaissance via Appcmd (via process_creation)
Malicious ManagementMailboxPicker Webshell Written by Diplomatic Specter
Windows Exchange Management: Set-OabVirtualDirectory ExternalUrl to script content
Pivot detection · T1505.003 · 9 related

Changelog

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