Potentially Suspicious Rundll32 Activity

detection:
  filter_main_parent_cpl:
    CommandLine|contains|all:
      - 'Shell32.dll'
      - 'Control_RunDLL'
      - '.cpl'
    ParentCommandLine|contains: '.cpl'
    ParentImage: 'C:\Windows\System32\control.exe'
  filter_main_screensaver:
    CommandLine|contains: 'shell32.dll,Control_RunDLL desk.cpl,screensaver,@screensaver'
  filter_main_startmenu:
    CommandLine|endswith: '.cpl",'
    CommandLine|startswith: '"C:\Windows\system32\rundll32.exe" Shell32.dll,Control_RunDLL "C:\Windows\System32\'
    ParentImage: 'C:\Windows\System32\control.exe'
  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'
  condition: selection and not 1 of filter_main_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

The commands documented for advpack.dll, comsvcs.dll, dfshim.dll, dfsvc.exe, ieadvpack.dll, ieframe.dll, mshtml.dll, pcwutl.dll, scrobj.dll, setupapi.dll, shdocvw.dll, shell32.dll, shimgvw.dll, syssetup.dll, url.dll, zipfldr.dll trip it: each is on its program’s page, read by CmdID.