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 Transport Agent Install Script

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Microsoft Exchange Transport Agent Install Script

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Identifies the use of Cmdlets and methods related to Microsoft Exchange Transport Agents install. Adversaries may leverage malicious Microsoft Exchange Transport Agents to execute tasks in response to adversary-defined criteria, establishing persistence.

Rule type: query

Rule indices:

winlogbeat-*
logs-windows.powershell*

Severity: low

Risk score: 21

Runs every: 60m

Searches indices from: now-119m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Persistence
Data Source: PowerShell Logs
Rule Type: BBR

Version: 7

Rule authors:

Elastic

Rule license: Elastic License v2

Setup

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Setup

The PowerShell Script Block Logging logging policy must be enabled. Steps to implement the logging policy with Advanced Audit Configuration:

Computer Configuration >
Administrative Templates >
Windows PowerShell >
Turn on PowerShell Script Block Logging (Enable)

Steps to implement the logging policy via registry:

reg add "hklm\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" /v EnableScriptBlockLogging /t REG_DWORD /d 1

Rule query

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event.category: "process" and host.os.type:windows and
  powershell.file.script_block_text : (
    (
    "Install-TransportAgent" or
    "Enable-TransportAgent"
    )
  ) and
  not user.id : "S-1-5-18" and
  not powershell.file.script_block_text : (
    "'Install-TransportAgent', 'Invoke-MonitoringProbe', 'Mount-Database', 'Move-ActiveMailboxDatabase'," or
    "'Enable-TransportAgent', 'Enable-TransportRule', 'Export-ActiveSyncLog', 'Export-AutoDiscoverConfig'," or
    ("scriptCmd.GetSteppablePipeline" and "ForwardHelpTargetName Install-TransportAgent")
  )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Server Software Component
- ID: T1505
- Reference URL: https://attack.mitre.org/techniques/T1505/
Sub-technique:
- Name: Transport Agent
- ID: T1505.002
- Reference URL: https://attack.mitre.org/techniques/T1505/002/
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Command and Scripting Interpreter
- ID: T1059
- Reference URL: https://attack.mitre.org/techniques/T1059/
Sub-technique:
- Name: PowerShell
- ID: T1059.001
- Reference URL: https://attack.mitre.org/techniques/T1059/001/

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