Suspicious Rundll32 Activity Invoking Sys File

A Sigma rule for process creation on Windows, by Florian Roth (Nextron Systems).

high 1 ATT&CK technique

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection1:
    CommandLine|contains: 'rundll32.exe'
  selection2:
    CommandLine|contains:
      - '.sys,'
      - '.sys '
  condition: all of selection*

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 Florian Roth (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.

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.

ATT&CK

the techniques it is tagged with

T1218.011System Binary Proxy Execution: Rundll32

Suspicious Rundll32 Activity Invoking Sys File

What it looks for

ATT&CK

Other rules for T1218.011 System Binary Proxy Execution: Rundll32