Microsoft Exchange Transport Agent Install Script

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*

Rule Severity: low
Risk Score: 21
Runs every: 60m
Searches indices from: now-119m
Maximum alerts per execution: ?
References:

Tags:

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

Version: ?
Rule authors:

• Elastic

Rule license: Elastic License v2

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

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

• 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/

Framework: MITRE ATT&CK

• 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/