Potentially Suspicious Rundll32 Activity — Sigma Rule

Rule metadata and linked tags

Author: juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2019-01-16 / 2023-05-17.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 1db2f4cdfc3b0e05364e96aca7ec33c622ddce75ffe7eda2622afa16ae7d72a9

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: Potentially Suspicious Rundll32 Activity
id: e593cf51-88db-4ee1-b920-37e89012a3c9
status: test
description: Detects suspicious execution of rundll32, with specific calls to some DLLs with known LOLBIN functionalities
references:
    - http://www.hexacorn.com/blog/2017/05/01/running-programs-via-proxy-jumping-on-a-edr-bypass-trampoline/
    - https://twitter.com/Hexacorn/status/885258886428725250
    - https://gist.github.com/ryhanson/227229866af52e2d963cf941af135a52
    - https://twitter.com/nas_bench/status/1433344116071583746 # dfshim.dll,ShOpenVerbShortcut
    - https://twitter.com/eral4m/status/1479106975967240209 # scrobj.dll,GenerateTypeLib
    - https://twitter.com/eral4m/status/1479080793003671557 # shimgvw.dll,ImageView_Fullscreen
author: juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)
date: 2019-01-16
modified: 2023-05-17
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - CommandLine|contains|all:
              - 'javascript:'
              - '.RegisterXLL'
        - CommandLine|contains|all:
              - 'url.dll'
              - 'OpenURL'
        - CommandLine|contains|all:
              - 'url.dll'
              - 'OpenURLA'
        - CommandLine|contains|all:
              - 'url.dll'
              - 'FileProtocolHandler'
        - CommandLine|contains|all:
              - 'zipfldr.dll'
              - 'RouteTheCall'
        - CommandLine|contains|all:
              - 'shell32.dll'
              - 'Control_RunDLL'
        - CommandLine|contains|all:
              - 'shell32.dll'
              - 'ShellExec_RunDLL'
        - CommandLine|contains|all:
              - 'mshtml.dll'
              - 'PrintHTML'
        - CommandLine|contains|all:
              - 'advpack.dll'
              - 'LaunchINFSection'
        - CommandLine|contains|all:
              - 'advpack.dll'
              - 'RegisterOCX'
        - CommandLine|contains|all:
              - 'ieadvpack.dll'
              - 'LaunchINFSection'
        - CommandLine|contains|all:
              - 'ieadvpack.dll'
              - 'RegisterOCX'
        - CommandLine|contains|all:
              - 'ieframe.dll'
              - 'OpenURL'
        - CommandLine|contains|all:
              - 'shdocvw.dll'
              - 'OpenURL'
        - CommandLine|contains|all:
              - 'syssetup.dll'
              - 'SetupInfObjectInstallAction'
        - CommandLine|contains|all:
              - 'setupapi.dll'
              - 'InstallHinfSection'
        - CommandLine|contains|all:
              - 'pcwutl.dll'
              - 'LaunchApplication'
        - CommandLine|contains|all:
              - 'dfshim.dll'
              - 'ShOpenVerbApplication'
        - CommandLine|contains|all:
              - 'dfshim.dll'
              - 'ShOpenVerbShortcut'
        - CommandLine|contains|all:
              - 'scrobj.dll'
              - 'GenerateTypeLib'
              - 'http'
        - CommandLine|contains|all:
              - 'shimgvw.dll'
              - 'ImageView_Fullscreen'
              - 'http'
        - CommandLine|contains|all:
              - 'comsvcs.dll'
              - 'MiniDump'
    filter_main_screensaver:
        CommandLine|contains: 'shell32.dll,Control_RunDLL desk.cpl,screensaver,@screensaver'
    filter_main_parent_cpl:  # Settings
        ParentImage: 'C:\Windows\System32\control.exe'
        ParentCommandLine|contains: '.cpl'
        CommandLine|contains|all:
            - 'Shell32.dll'
            - 'Control_RunDLL'
            - '.cpl'
    filter_main_startmenu:
        ParentImage: 'C:\Windows\System32\control.exe'
        CommandLine|startswith: '"C:\Windows\system32\rundll32.exe" Shell32.dll,Control_RunDLL "C:\Windows\System32\'
        CommandLine|endswith: '.cpl",'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - False positives depend on scripts and administrative tools used in the monitored environment
level: medium

Original YAML and metadata in JSON

False positives

• False positives depend on scripts and administrative tools used in the monitored environment

Source references

• http://www.hexacorn.com/blog/2017/05/01/running-programs-via-proxy-jumping-on-a-edr-bypass-trampoline/
• https://twitter.com/Hexacorn/status/885258886428725250
• https://gist.github.com/ryhanson/227229866af52e2d963cf941af135a52
• https://twitter.com/nas_bench/status/1433344116071583746
• https://twitter.com/eral4m/status/1479106975967240209
• https://twitter.com/eral4m/status/1479080793003671557