Uncommon Child Process Of Appvlp.EXE — Sigma Rule

Rule metadata and linked tags

Author: Sreeman. Source status: test; severity: medium. Source dates: 2020-03-13 / 2023-11-09.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 4da348fc02a27da4c1d88d8bbe2f715dbb7e19bc7bb7e75192f49784893982e2

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Uncommon Child Process Of Appvlp.EXE
id: 9c7e131a-0f2c-4ae0-9d43-b04f4e266d43
status: test
description: |
    Detects uncommon child processes of Appvlp.EXE
    Appvlp or the Application Virtualization Utility is included with Microsoft Office. Attackers are able to abuse "AppVLP" to execute shell commands.
    Normally, this binary is used for Application Virtualization, but it can also be abused to circumvent the ASR file path rule folder
    or to mark a file as a system file.
references:
    - https://lolbas-project.github.io/lolbas/OtherMSBinaries/Appvlp/
author: Sreeman
date: 2020-03-13
modified: 2023-11-09
tags:
    - attack.stealth
    - attack.t1218
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\appvlp.exe'
    # Note: Filters based on data from EchoTrail: https://www.echotrail.io/insights/search/appvlp.exe/
    filter_main_generic:
        Image|endswith:
            - ':\Windows\SysWOW64\rundll32.exe'
            - ':\Windows\System32\rundll32.exe'
    filter_optional_office_msoasb:
        Image|contains: ':\Program Files\Microsoft Office'
        Image|endswith: '\msoasb.exe'
    filter_optional_office_skype:
        Image|contains|all:
            - ':\Program Files\Microsoft Office'
            - '\SkypeSrv\'
        Image|endswith: '\SKYPESERVER.EXE'
    filter_optional_office_msouc:
        Image|contains: ':\Program Files\Microsoft Office'
        Image|endswith: '\MSOUC.EXE'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://lolbas-project.github.io/lolbas/OtherMSBinaries/Appvlp/