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Suspicious Outlook Child Process

Elastic Stack Serverless Security

Identifies suspicious child processes spawned by MS Outlook, which can indicate a potential masquerading or the exploitation of a vulnerability on the application causing it to execute code.

Rule type: eql

Rule indices:

  • logs-endpoint.events.process-*

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-9m (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
  • Tactic: Persistence
  • Rule Type: BBR
  • Data Source: Elastic Defend

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

process where host.os.type == "windows" and event.type == "start" and
  process.parent.name : "outlook.exe" and
  not (
    (
      process.executable : (
        "?:\\Program Files\\*",
        "?:\\Program Files (x86)\\*",
        "?:\\Windows\\System32\\WerFault.exe",
        "?:\\Windows\\SysWOW64\\WerFault.exe",
        "?:\\Windows\\system32\\wermgr.exe",
        "?:\\Users\\*\\AppData\\Local\\Microsoft\\Teams\\current\\Teams.exe",
        "?:\\Users\\*\\AppData\\Local\\Temp\\NewOutlookInstall\\NewOutlookInstaller.exe",
        "?:\\Users\\*\\AppData\\Local\\Google\\Chrome\\Application\\chrome.exe",
        "?:\\Users\\*\\AppData\\Local\\Island\\Island\\Application\\Island.exe",
        "?:\\Users\\*\\AppData\\Local\\Mozilla Firefox\\firefox.exe",
        "?:\\Users\\*\\AppData\\Roaming\\Zoom\\bin\\Zoom.exe",
        "?:\\Windows\\System32\\IME\\SHARED\\IMEWDBLD.EXE",
        "?:\\Windows\\System32\\spool\\drivers\\x64\\*",
        "?:\\Windows\\System32\\prevhost.exe",
        "?:\\Windows\\System32\\dwwin.exe",
        "?:\\Windows\\System32\\mspaint.exe",
        "?:\\Windows\\SysWOW64\\mspaint.exe",
        "?:\\Windows\\System32\\notepad.exe",
        "?:\\Windows\\SysWOW64\\notepad.exe",
        "?:\\Windows\\System32\\smartscreen.exe",
        "?:\\Windows\\explorer.exe",
        "?:\\Windows\\splwow64.exe"
      ) and process.code_signature.trusted == true
    ) or
    (
      process.name : "rundll32.exe" and
      process.args : "*hpmsn???.dll,MonitorPrintJobStatus*"
    )
  )

Framework: MITRE ATT&CKTM