title: Potential NT API Stub Patching
id: b916cba1-b38a-42da-9223-17114d846fd6
status: deprecated
description: Detects potential NT API stub patching as seen used by the project PatchingAPI
references:
    - https://web.archive.org/web/20230106211702/https://github.com/D1rkMtr/UnhookingPatch
    - https://twitter.com/D1rkMtr/status/1611471891193298944?s=20
author: frack113
date: 2023/01/07
modified: 2024/05/27
tags:
    - attack.defense_evasion
    - attack.t1562.002
logsource:
    category: process_access
    product: windows
detection:
    selection:
        GrantedAccess: '0x1FFFFF'
        CallTrace|startswith: 'C:\Windows\SYSTEM32\ntdll.dll+'
        CallTrace|contains: '|UNKNOWN('
        CallTrace|endswith: ')'
    filter_main_generic:
        # To avoid FP with installed applications. This filter assumes that if an application is located here. The attacker has already achieved admin rights
        - SourceImage|contains:
              - ':\Program Files\'
              - ':\Program Files (x86)\'
              - ':\Windows\System32\'
              - ':\Windows\SysWOW64\'
        - TargetImage|contains:
              - ':\Program Files\'
              - ':\Program Files (x86)\'
              - ':\Windows\System32\'
              - ':\Windows\SysWOW64\'
    filter_optional_thor:
        SourceImage|endswith:
            - '\thor.exe'
            - '\thor64.exe'
    filter_optional_githubdesktop:
        SourceImage|contains|all:
            - ':\Users\'
            - '\AppData\Local\GitHubDesktop\app-'
        SourceImage|endswith:
            - '\GitHubDesktop.exe'
            - '\resources\app\git\usr\bin\sh.exe'
        TargetImage|contains|all:
            - ':\Users\'
            - '\AppData\Local\GitHubDesktop\app-'
    filter_main_dotnet:
        SourceImage|contains: ':\Windows\Microsoft.NET\'
        TargetImage|contains: ':\Windows\Microsoft.NET\'
    filter_main_taskhost:
        SourceImage|contains:
            - ':\Windows\system32\taskhostw.exe'
            - ':\Windows\system32\taskhost.exe'
        TargetImage|contains:
            - ':\Windows\Microsoft.NET\Framework\v'
            - ':\Windows\Microsoft.NET\Framework64\v'
        TargetImage|endswith: '\NGenTask.exe'
    filter_optional_teams_to_update:
        SourceImage|endswith: '\AppData\Local\Microsoft\Teams\stage\Teams.exe'
        TargetImage|endswith: '\AppData\Local\Microsoft\Teams\Update.exe'
    filter_optional_teams_update_regsvr32:
        SourceImage|endswith: '\AppData\Local\Microsoft\Teams\Update.exe'
        TargetImage|endswith: ':\WINDOWS\SysWOW64\regsvr32.exe'
    filter_optional_teams_update_to_teams:
        SourceImage|endswith: '\AppData\Local\Microsoft\Teams\Update.exe'
        TargetImage|endswith: '\AppData\Local\Microsoft\Teams\stage\Teams.exe'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium