sigma-rules/rules_building_block/persistence_transport_agent_exchange.toml

[metadata]
creation_date = "2023/07/14"
integration = ["windows"]
maturity = "production"
updated_date = "2026/02/09"

[rule]
author = ["Elastic"]
building_block_type = "default"
description = """
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.
"""
from = "now-119m"
index = ["winlogbeat-*", "logs-windows.powershell*"]
interval = "60m"
language = "kuery"
license = "Elastic License v2"
name = "Deprecated - Microsoft Exchange Transport Agent Install Script"
risk_score = 21
rule_id = "846fe13f-6772-4c83-bd39-9d16d4ad1a81"
setup = """## Setup

PowerShell Script Block Logging must be enabled to generate the events used by this rule (e.g., 4104).
Setup instructions: https://ela.st/powershell-logging-setup
"""
severity = "low"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Persistence",
    "Data Source: PowerShell Logs",
    "Rule Type: BBR",
]
timestamp_override = "event.ingested"
type = "query"

query = '''
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")
  )
'''


[[rule.filters]]

[rule.filters.meta]
negate = true
[rule.filters.query.wildcard."file.path"]
case_insensitive = true
value = "?:\\\\Users\\\\*\\\\AppData\\\\Roaming\\\\Microsoft\\\\Exchange\\\\RemotePowerShell\\\\*"
[[rule.filters]]

[rule.filters.meta]
negate = true
[rule.filters.query.wildcard."file.path"]
case_insensitive = true
value = "?:\\\\Users\\\\*\\\\AppData\\\\Local\\\\Temp\\\\tmp_????????.???\\\\tmp_????????.???.ps?1"
[[rule.filters]]

[rule.filters.meta]
negate = true
[rule.filters.query.wildcard."file.path"]
case_insensitive = true
value = "?:\\\\Windows\\\\TEMP\\\\tmp_????????.???\\\\tmp_????????.???.ps?1"
[[rule.filters]]

[rule.filters.meta]
negate = true
[rule.filters.query.wildcard."file.path"]
case_insensitive = true
value = "?:\\\\Users\\\\*\\\\AppData\\\\Local\\\\Temp\\\\*\\\\tmp_????????.???\\\\tmp_????????.???.ps?1"
[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1505"
name = "Server Software Component"
reference = "https://attack.mitre.org/techniques/T1505/"
[[rule.threat.technique.subtechnique]]
id = "T1505.002"
name = "Transport Agent"
reference = "https://attack.mitre.org/techniques/T1505/002/"



[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"
[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"
[[rule.threat.technique.subtechnique]]
id = "T1059.001"
name = "PowerShell"
reference = "https://attack.mitre.org/techniques/T1059/001/"



[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"