Microsoft Exchange Server UM Spawning Suspicious Processesedit
Identifies suspicious processes being spawned by the Microsoft Exchange Server Unified Messaging (UM) service. This activity has been observed exploiting CVE-2021-26857.
Rule type: eql
Rule indices:
- logs-endpoint.events.*
- winlogbeat-*
- logs-windows.*
Severity: medium
Risk score: 47
Runs every: 5 minutes
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References:
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Initial Access
Version: 4 (version history)
Added (Elastic Stack release): 7.12.0
Last modified (Elastic Stack release): 8.4.0
Rule authors: Elastic, Austin Songer
Rule license: Elastic License v2
Potential false positivesedit
Legitimate processes may be spawned from the Microsoft Exchange Server Unified Messaging (UM) service. If known processes are causing false positives, they can be exempted from the rule.
Investigation guideedit
Rule queryedit
process where event.type == "start" and process.parent.name :
("UMService.exe", "UMWorkerProcess.exe") and not
process.executable :
("?:\\Windows\\System32\\werfault.exe",
"?:\\Windows\\System32\\wermgr.exe", "?:\\Program
Files\\Microsoft\\Exchange Server\\V??\\Bin\\UMWorkerProcess.exe",
"D:\\Exchange 2016\\Bin\\UMWorkerProcess.exe",
"E:\\ExchangeServer\\Bin\\UMWorkerProcess.exe")
Threat mappingedit
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
-
Technique:
- Name: Exploit Public-Facing Application
- ID: T1190
- Reference URL: https://attack.mitre.org/techniques/T1190/
Rule version historyedit
- Version 4 (8.4.0 release)
-
-
Updated query, changed from:
process where event.type == "start" and process.parent.name : ("UMService.exe", "UMWorkerProcess.exe") and not process.name : ("werfault.exe", "wermgr.exe")
-
- Version 2 (8.2.0 release)
-
- Formatting only