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Unusual Process Extension

Elastic Stack Serverless Security

Identifies processes running with unusual extensions that are not typically valid for Windows executables.

Rule type: eql

Rule indices:

  • logs-endpoint.events.process-*

Severity: low

Risk score: 21

Runs every: 60m

Searches indices from: now-119m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[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: Defense Evasion
  • Data Source: Elastic Defend
  • Rule Type: BBR

Version: 4

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

process where host.os.type == "windows" and event.type == "start" and
  process.executable : "?*" and
  not process.name : ("*.exe", "*.com", "*.scr", "*.tmp", "*.dat") and
  not process.executable :
    (
      "MemCompression",
      "Registry",
      "vmmem",
      "vmmemWSL",
      "?:\\Program Files\\Dell\\SupportAssistAgent\\*.p5x",
      "?:\\Program Files\\Docker\\Docker\\com.docker.service",
      "?:\\Users\\*\\AppData\\Local\\Intel\\AGS\\Libs\\AGSRunner.bin",
      "\\Device\\Mup\\*\\Software Management\\Select.Html.dep",
      "?:\\DJJApplications\\MedicalRecords\\bin\\Select.Html.dep",
      "?:\\ProgramData\\Software Management\\Select.Html.dep",
      "?:\\Program Files (x86)\\EnCase Applications\\Examiner Service\\EnCase64\\enhkey.dll",
      "?:\\Program Files (x86)\\Panda Security\\WAC\\PSNAEInj64.dll",
      "?:\\Program Files (x86)\\Johnson Controls\\LicenseActivator\\crp32002.ngn"
    ) and
  not (
    (process.name : "C9632CF058AE4321B6B0B5EA39B710FE" and process.code_signature.subject_name == "Dell Inc") or
    (process.name : "*.upd" and process.code_signature.subject_name == "Bloomberg LP") or
    (process.name: "FD552E21-686E-413C-931D-3B82A9D29F3B" and process.code_signature.subject_name: "Adobe Inc.") or
    (process.name: "3B91051C-AE82-43C9-BCEF-0309CD2DD9EB" and process.code_signature.subject_name: "McAfee, LLC") or
    (process.name: "soffice.bin" and process.code_signature.subject_name: "The Document Foundation") or
    (process.name: ("VeeamVixProxy_*", "{????????-????-????-????-????????????}") and process.code_signature.subject_name: "Veeam Software Group GmbH") or
    (process.name: "1cv8p64.bin" and process.code_signature.subject_name: "LLC 1C-Soft") or
    (process.name: "AGSRunner.bin" and process.code_signature.subject_name: "Intel Corporation")
  )

Framework: MITRE ATT&CKTM