ImageLoad via Windows Update Auto Update Client

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Identifies abuse of the Windows Update Auto Update Client (wuauclt.exe) to load an arbitrary DLL. This behavior is used as a defense evasion technique to blend-in malicious activity with legitimate Windows software.

Rule type: eql

Rule indices:

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

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
  • Defense Evasion
  • Elastic Endgame

Version: 102 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.6.0

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.pe.original_file_name == "wuauclt.exe" or process.name :
"wuauclt.exe") and /* necessary windows update client args to load
a dll */ process.args : "/RunHandlerComServer" and process.args :
"/UpdateDeploymentProvider" and /* common paths writeable by a
standard user where the target DLL can be placed */ process.args :
("C:\\Users\\*.dll", "C:\\ProgramData\\*.dll",
"C:\\Windows\\Temp\\*.dll", "C:\\Windows\\Tasks\\*.dll")

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 102 (8.6.0 release)
  • Formatting only
Version 101 (8.5.0 release)
  • Updated query, changed from:

    process where event.type in ("start", "process_started") and
    (process.pe.original_file_name == "wuauclt.exe" or process.name :
    "wuauclt.exe") and /* necessary windows update client args to load
    a dll */ process.args : "/RunHandlerComServer" and process.args :
    "/UpdateDeploymentProvider" and /* common paths writeable by a
    standard user where the target DLL can be placed */ process.args :
    ("C:\\Users\\*.dll", "C:\\ProgramData\\*.dll",
    "C:\\Windows\\Temp\\*.dll", "C:\\Windows\\Tasks\\*.dll")
Version 9 (8.4.0 release)
  • Formatting only
Version 7 (8.3.0 release)
  • Formatting only
Version 5 (8.2.0 release)
  • Formatting only
Version 3 (7.12.0 release)
  • Formatting only
Version 2 (7.11.2 release)
  • Formatting only