Potential Port Monitor or Print Processor Registration Abuse

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Potential Port Monitor or Print Processor Registration Abuse

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Identifies port monitor and print processor registry modifications. Adversaries may abuse port monitor and print processors to run malicious DLLs during system boot that will be executed as SYSTEM for privilege escalation and/or persistence, if permissions allow writing a fully-qualified pathname for that DLL.

Rule type: eql

Rule indices:

  • logs-endpoint.events.registry-*
  • endgame-*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Privilege Escalation
  • Data Source: Elastic Endgame
  • Data Source: Elastic Defend

Version: 107

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

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registry where host.os.type == "windows" and event.type == "change" and
  registry.path : (
      "HKLM\\SYSTEM\\*ControlSet*\\Control\\Print\\Monitors\\*",
      "HKLM\\SYSTEM\\*ControlSet*\\Control\\Print\\Environments\\Windows*\\Print Processors\\*",
      "\\REGISTRY\\MACHINE\\SYSTEM\\*ControlSet*\\Control\\Print\\Monitors\\*",
      "\\REGISTRY\\MACHINE\\SYSTEM\\*ControlSet*\\Control\\Print\\Environments\\Windows*\\Print Processors\\*"
  ) and registry.data.strings : "*.dll" and
  /* exclude SYSTEM SID - look for changes by non-SYSTEM user */
  not user.id : "S-1-5-18"

Framework: MITRE ATT&CKTM