Exchange Set OabVirtualDirectory ExternalUrl Property — Sigma Rule

Rule metadata and linked tags

Author: Jose Rodriguez @Cyb3rPandaH. Source status: test; severity: high. Source dates: 2021-03-15 / 2023-01-23.

{
  "product": "windows",
  "service": "msexchange-management"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 329217678176702de3121a890f0a50b1a6b2df95c6a350f85883543e53a6e58d

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Exchange Set OabVirtualDirectory ExternalUrl Property
id: 9db37458-4df2-46a5-95ab-307e7f29e675
status: test
description: Rule to detect an adversary setting OabVirtualDirectory External URL property to a script in Exchange Management log
references:
    - https://twitter.com/OTR_Community/status/1371053369071132675
author: Jose Rodriguez @Cyb3rPandaH
date: 2021-03-15
modified: 2023-01-23
tags:
    - attack.persistence
    - attack.t1505.003
logsource:
    product: windows
    service: msexchange-management
detection:
    keywords:
        '|all':
            - 'Set-OabVirtualDirectory'
            - 'ExternalUrl'
            - 'Page_Load'
            - 'script'
    condition: keywords
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://twitter.com/OTR_Community/status/1371053369071132675