CmdID

CmdID / Rules / Windows

Rundll32.EXE Calling DllRegisterServer Export Function Explicitly

A Sigma rule for process creation on Windows, from SigmaHQ’s threat hunting rules, by Andreas Braathen (mnemonic.io).

medium 1 ATT&CK technique 1 program it names

What it looks for

its detection, as SigmaHQ writes it
detection:
  filter_main_legit_paths:
    CommandLine|contains:
      - ':\Program Files (x86)'
      - ':\Program Files\'
      - ':\Windows\System32\'
      - ':\Windows\SysWOW64\'
  selection_cmdline:
    CommandLine|contains: 'DllRegisterServer'
  selection_image:
    - Image|endswith: '\rundll32.exe'
    - OriginalFileName: 'RUNDLL32.EXE'
  condition: all of 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 Andreas Braathen (mnemonic.io), 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.

None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.

Programs and files it names

their pages here
rundll32.exe

ATT&CK

the techniques it is tagged with
T1218System Binary Proxy Execution

Other rules for T1218 System Binary Proxy Execution

Suspicious AddinUtil.EXE CommandLine Execution · Uncommon Child Process Of AddinUtil.EXE · Uncommon AddinUtil.EXE CommandLine Execution · AddinUtil.EXE Execution From Uncommon Directory · AgentExecutor PowerShell Execution · Suspicious AgentExecutor PowerShell Execution · Uncommon Child Process Of Appvlp.EXE · Uncommon Assistive Technology Applications Execution Via AtBroker.EXE · BitLockerTogo.EXE Execution · DLL Loaded via CertOC.EXE · Suspicious DLL Loaded via CertOC.EXE · Potential NTLM Coercion Via Certutil.EXE