proc_creation_win_susp_bad_opsec_sacrificial_processes.yml

title: Bad Opsec Defaults Sacrificial Processes With Improper Arguments
id: a7c3d773-caef-227e-a7e7-c2f13c622329
related:
    - id: f5647edc-a7bf-4737-ab50-ef8c60dc3add
      type: obsoletes
status: experimental
description: |
    Detects attackers using tooling with bad opsec defaults.
    E.g. spawning a sacrificial process to inject a capability into the process without taking into account how the process is normally run.
    One trivial example of this is using rundll32.exe without arguments as a sacrificial process (default in CS, now highlighted by c2lint), running WerFault without arguments (Kraken - credit am0nsec), and other examples.
references:
    - https://blog.malwarebytes.com/malwarebytes-news/2020/10/kraken-attack-abuses-wer-service/
    - https://www.cobaltstrike.com/help-opsec
    - https://twitter.com/CyberRaiju/status/1251492025678983169
    - https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/regsvr32
    - https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/rundll32
    - https://docs.microsoft.com/en-us/dotnet/framework/tools/regasm-exe-assembly-registration-tool
    - https://docs.microsoft.com/en-us/dotnet/framework/tools/regsvcs-exe-net-services-installation-tool#feedback
author: Oleg Kolesnikov @securonix invrep_de, oscd.community, Florian Roth (Nextron Systems), Christian Burkard (Nextron Systems)
date: 2020/10/23
modified: 2023/01/25
tags:
    - attack.defense_evasion
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection1:
        Image|endswith: '\WerFault.exe'
        CommandLine|endswith: 'WerFault.exe'
    selection2:
        Image|endswith: '\rundll32.exe'
        CommandLine|endswith: 'rundll32.exe'
    selection3:
        Image|endswith: '\regsvcs.exe'
        CommandLine|endswith: 'regsvcs.exe'
    selection4:
        Image|endswith: '\regasm.exe'
        CommandLine|endswith: 'regasm.exe'
    selection5:
        Image|endswith: '\regsvr32.exe'
        CommandLine|endswith: 'regsvr32.exe'
    filter_edge_update:
        ParentImage|startswith: 'C:\Users\'
        ParentImage|contains: '\AppData\Local\Microsoft\EdgeUpdate\Install\{'
        ParentImage|endswith: '\setup.exe'
        ParentCommandLine|contains: '\setup.exe" --install-archive="C:\Users\'
    condition: 1 of selection* and not 1 of filter*
fields:
    - ParentImage
    - ParentCommandLine
falsepositives:
    - Unlikely
level: high