Suspicious Outlook Child Process

Hunt Hypothesis

Detects a suspicious process spawning from an Outlook process.

Detection Rule

Sigma (Original)

title: Suspicious Outlook Child Process
id: 208748f7-881d-47ac-a29c-07ea84bf691d
related:
    - id: 438025f9-5856-4663-83f7-52f878a70a50 # Office Child Processes
      type: derived
    - id: e212d415-0e93-435f-9e1a-f29005bb4723 # Outlook Remote Child Process
      type: derived
status: test
description: Detects a suspicious process spawning from an Outlook process.
references:
    - https://www.hybrid-analysis.com/sample/465aabe132ccb949e75b8ab9c5bda36d80cf2fd503d52b8bad54e295f28bbc21?environmentId=100
    - https://mgreen27.github.io/posts/2018/04/02/DownloadCradle.html
author: Michael Haag, Florian Roth (Nextron Systems), Markus Neis, Elastic, FPT.EagleEye 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'        # https://github.com/elastic/detection-rules/blob/c76a39796972ecde44cb1da6df47f1b6562c9770/rules/windows/defense_evasion_execution_msbuild_started_by_office_app.toml
            - '\msdt.exe'           # CVE-2022-30190
            - '\mshta.exe'
            - '\msiexec.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\regsvr32.exe'
            - '\schtasks.exe'
            - '\scrcons.exe'
            - '\scriptrunner.exe'
            - '\sh.exe'
            - '\svchost.exe'        # https://www.vmray.com/analyses/2d2fa29185ad/report/overview.html
            - '\wmic.exe'           # https://app.any.run/tasks/c903e9c8-0350-440c-8688-3881b556b8e0/
            - '\wscript.exe'
            # Several FPs with rundll32.exe
            # We started excluding specific use cases and ended up commenting out the rundll32.exe sub processes completely
            # - '\rundll32.exe'
            # filter_outlook_photoviewer:  # https://twitter.com/Luke_Hamp/status/1495919717760237568
            #   ParentImage|endswith: '\OUTLOOK.EXE'
            #   Image|endswith: '\rundll32.exe'
            #   CommandLine|contains: '\PhotoViewer.dll'
            # filter_outlook_printattachments:  # https://twitter.com/KickaKamil/status/1496238278659485696
            #   ParentImage|endswith: '\OUTLOOK.EXE'
            #   Image|endswith: '\rundll32.exe'
            #   CommandLine|contains|all:
            #     - 'shell32.dll,Control_RunDLL'
            #     - '\SYSTEM32\SPOOL\DRIVERS\'
    condition: selection # and not 1 of filter*
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imProcessCreate
| where (ParentProcessName endswith "\\OUTLOOK.EXE" or ActingProcessName endswith "\\OUTLOOK.EXE") and (TargetProcessName endswith "\\AppVLP.exe" or TargetProcessName endswith "\\bash.exe" or TargetProcessName endswith "\\cmd.exe" or TargetProcessName endswith "\\cscript.exe" or TargetProcessName endswith "\\forfiles.exe" or TargetProcessName endswith "\\hh.exe" or TargetProcessName endswith "\\mftrace.exe" or TargetProcessName endswith "\\msbuild.exe" or TargetProcessName endswith "\\msdt.exe" or TargetProcessName endswith "\\mshta.exe" or TargetProcessName endswith "\\msiexec.exe" or TargetProcessName endswith "\\powershell.exe" or TargetProcessName endswith "\\pwsh.exe" or TargetProcessName endswith "\\regsvr32.exe" or TargetProcessName endswith "\\schtasks.exe" or TargetProcessName endswith "\\scrcons.exe" or TargetProcessName endswith "\\scriptrunner.exe" or TargetProcessName endswith "\\sh.exe" or TargetProcessName endswith "\\svchost.exe" or TargetProcessName endswith "\\wmic.exe" or TargetProcessName endswith "\\wscript.exe")

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Execution
• Technique: T1204.002 — T1204.002

References

• https://www.hybrid-analysis.com/sample/465aabe132ccb949e75b8ab9c5bda36d80cf2fd503d52b8bad54e295f28bbc21?environmentId=100
• https://mgreen27.github.io/posts/2018/04/02/DownloadCradle.html
• SigmaHQ Rule