WMI Backdoor Exchange Transport Agent — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: critical. Source dates: 2019-10-11 / 2023-02-08.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: cb1e1afc2dc6670a60ae34e10060d1b40552b2c4529e4f16b9d42d54cce54000

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: WMI Backdoor Exchange Transport Agent
id: 797011dc-44f4-4e6f-9f10-a8ceefbe566b
status: test
description: Detects a WMI backdoor in Exchange Transport Agents via WMI event filters
references:
    - https://twitter.com/cglyer/status/1182389676876980224
    - https://twitter.com/cglyer/status/1182391019633029120
author: Florian Roth (Nextron Systems)
date: 2019-10-11
modified: 2023-02-08
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1546.003
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\EdgeTransport.exe'
    filter_conhost:
        Image: 'C:\Windows\System32\conhost.exe'
    filter_oleconverter:  # FP also documented in https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=18
        Image|startswith: 'C:\Program Files\Microsoft\Exchange Server\'
        Image|endswith: '\Bin\OleConverter.exe'
    condition: selection and not 1 of filter_*
falsepositives:
    - Unknown
level: critical

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://twitter.com/cglyer/status/1182389676876980224
• https://twitter.com/cglyer/status/1182391019633029120