IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Microsoft Exchange Worker Spawning Suspicious Processes

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Microsoft Exchange Worker Spawning Suspicious Processes

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Identifies suspicious processes being spawned by the Microsoft Exchange Server worker process (w3wp). This activity may indicate exploitation activity or access to an existing web shell backdoor.

Rule type: eql

Rule indices:

logs-endpoint.events.*
winlogbeat-*
logs-windows.*

Severity: high

Risk score: 73

Runs every: 5m

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: 101

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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Rule query

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process where event.type == "start" and
  process.parent.name : "w3wp.exe" and process.parent.args : "MSExchange*AppPool" and
  (process.name : ("cmd.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe") or
  process.pe.original_file_name in ("cmd.exe", "powershell.exe", "pwsh.dll", "powershell_ise.exe"))

Framework: MITRE ATT&CK^TM

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/

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