Detection rules › Sigma
WMI Backdoor Exchange Transport Agent
Detects a WMI backdoor in Exchange Transport Agents via WMI event filters
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1546.003 Event Triggered Execution: Windows Management Instrumentation Event Subscription |
| Privilege Escalation | T1546.003 Event Triggered Execution: Windows Management Instrumentation Event Subscription |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
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
Stages and Predicates
Stage 0: condition
selection and not 1 of filter_*Stage 1: selection
selection:
ParentImage|endswith: '\EdgeTransport.exe'
Stage 2: not filter_*
filter_conhost:
Image: 'C:\Windows\System32\conhost.exe'
filter_oleconverter:
Image|startswith: 'C:\Program Files\Microsoft\Exchange Server\'
Image|endswith: '\Bin\OleConverter.exe'
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
Image | ends_with | \Bin\OleConverter.exe |
Image | starts_with | C:\Program Files\Microsoft\Exchange Server\ |
Image | eq | C:\Windows\System32\conhost.exe |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
ParentImage | ends_with |
|