MMC Executing Files with Reversed Extensions Using RTLO Abuse

A Sigma rule for process creation on Windows, by Swachchhanda Shrawan Poudel (Nextron Systems).

high 3 ATT&CK techniques 1 program it names

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection_commandline:
    CommandLine|contains:
      - 'cod.msc'
      - 'fdp.msc'
      - 'ftr.msc'
      - 'lmth.msc'
      - 'slx.msc'
      - 'tdo.msc'
      - 'xcod.msc'
      - 'xslx.msc'
      - 'xtpp.msc'
  selection_image:
    - Image|endswith: '\mmc.exe'
    - OriginalFileName: 'MMC.exe'
  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 Swachchhanda Shrawan Poudel (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.

Programs and files it names

their pages here

mmc.exe

ATT&CK

the techniques it is tagged with

T1036.002Masquerading: Right-to-Left Override

T1204.002User Execution: Malicious File

T1218.014System Binary Proxy Execution: MMC

MMC Executing Files with Reversed Extensions Using RTLO Abuse

What it looks for

Programs and files it names

ATT&CK

Other rules for T1036.002 Masquerading: Right-to-Left Override