Permission Check Via Accesschk.EXE — Sigma Rule

Rule metadata and linked tags

Author: Teymur Kheirkhabarov (idea), Mangatas Tondang, oscd.community, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2020-10-13 / 2023-02-20.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a5b43691601ee59f5bd02143377bf4e872e4425a4a3d81b1bf6569e18cc931c7

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: Permission Check Via Accesschk.EXE
id: c625d754-6a3d-4f65-9c9a-536aea960d37
status: test
description: Detects the usage of the "Accesschk" utility, an access and privilege audit tool developed by SysInternal and often being abused by attacker to verify process privileges
references:
    - https://speakerdeck.com/heirhabarov/hunting-for-privilege-escalation-in-windows-environment?slide=43
    - https://www.youtube.com/watch?v=JGs-aKf2OtU&ab_channel=OFFZONEMOSCOW
    - https://github.com/carlospolop/PEASS-ng/blob/fa0f2e17fbc1d86f1fd66338a40e665e7182501d/winPEAS/winPEASbat/winPEAS.bat
    - https://github.com/gladiatx0r/Powerless/blob/04f553bbc0c65baf4e57344deff84e3f016e6b51/Powerless.bat
author: Teymur Kheirkhabarov (idea), Mangatas Tondang, oscd.community, Nasreddine Bencherchali (Nextron Systems)
date: 2020-10-13
modified: 2023-02-20
tags:
    - attack.discovery
    - attack.t1069.001
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Product|endswith: 'AccessChk'
        - Description|contains: 'Reports effective permissions'
        - Image|endswith:
              - '\accesschk.exe'
              - '\accesschk64.exe'
        - OriginalFileName: 'accesschk.exe'
    selection_cli:
        CommandLine|contains: # These are the most common flags used with this tool. You could add other combinations if needed
            - 'uwcqv '
            - 'kwsu '
            - 'qwsu '
            - 'uwdqs '
    condition: all of selection*
falsepositives:
    - System administrator Usage
level: medium

Original YAML and metadata in JSON

False positives

• System administrator Usage

Source references

• https://speakerdeck.com/heirhabarov/hunting-for-privilege-escalation-in-windows-environment?slide=43
• https://www.youtube.com/watch?v=JGs-aKf2OtU&ab_channel=OFFZONEMOSCOW
• https://github.com/carlospolop/PEASS-ng/blob/fa0f2e17fbc1d86f1fd66338a40e665e7182501d/winPEAS/winPEASbat/winPEAS.bat
• https://github.com/gladiatx0r/Powerless/blob/04f553bbc0c65baf4e57344deff84e3f016e6b51/Powerless.bat