Windows: Suspicious Process Spawn by Outlook Parent

Alerts on Windows process launches where Outlook.exe spawns known high-risk command execution binaries.

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windows-suspicious-process-spawn-by-outlook-parent-208748f7

title: "Windows: Suspicious Process Spawn by Outlook Parent"
id: 0ef42c8e-5d44-4461-8b8b-31d0af7ffcad
related:
  - id: 438025f9-5856-4663-83f7-52f878a70a50
    type: derived
  - id: e212d415-0e93-435f-9e1a-f29005bb4723
    type: derived
  - id: 208748f7-881d-47ac-a29c-07ea84bf691d
    type: derived
status: test
description: This rule flags Windows process creation events where the parent process is Outlook.exe and the child process is one of several commonly abused executables (for example, PowerShell, MSHTA, regsvr32, wmic, and scheduled task utilities). Such parent/child relationships are important because attackers frequently leverage Outlook to start execution chains that run scripts, downloaders, or other payload components. It relies on process creation telemetry with parent and image file paths captured in fields like ParentImage and Image, including process names identified by their filename suffixes.
references:
  - https://www.hybrid-analysis.com/sample/465aabe132ccb949e75b8ab9c5bda36d80cf2fd503d52b8bad54e295f28bbc21?environmentId=100
  - https://mgreen27.github.io/posts/2018/04/02/DownloadCradle.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_office_outlook_susp_child_processes.yml
author: Michael Haag, Florian Roth (Nextron Systems), Markus Neis, Elastic, FPT.EagleEye Team, Huntrule Team
date: 2022-02-28
modified: 2023-02-04
tags:
  - attack.execution
  - attack.t1204.002
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    ParentImage|endswith: \OUTLOOK.EXE
    Image|endswith:
      - \AppVLP.exe
      - \bash.exe
      - \cmd.exe
      - \cscript.exe
      - \forfiles.exe
      - \hh.exe
      - \mftrace.exe
      - \msbuild.exe
      - \msdt.exe
      - \mshta.exe
      - \msiexec.exe
      - \powershell.exe
      - \pwsh.exe
      - \regsvr32.exe
      - \schtasks.exe
      - \scrcons.exe
      - \scriptrunner.exe
      - \sh.exe
      - \svchost.exe
      - \wmic.exe
      - \wscript.exe
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1

What it detects

This rule flags Windows process creation events where the parent process is Outlook.exe and the child process is one of several commonly abused executables (for example, PowerShell, MSHTA, regsvr32, wmic, and scheduled task utilities). Such parent/child relationships are important because attackers frequently leverage Outlook to start execution chains that run scripts, downloaders, or other payload components. It relies on process creation telemetry with parent and image file paths captured in fields like ParentImage and Image, including process names identified by their filename suffixes.

Known false positives

Unknown

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.