Sigma rule: Wlrmdr.EXE Uncommon Argument Or Child Process

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-daad9c388ee0, updated 2025-10-31T00:00:00.000Z.

Rule

Title: Wlrmdr.EXE Uncommon Argument Or Child Process
Status: experimental
Level: medium
Author: frack113, manasmbellani
Date: 2022-02-16
Modified: 2025-10-31
File: rules/windows/process_creation/proc_creation_win_wlrmdr_uncommon_child_process.yml
Commit: ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the execution of "Wlrmdr.exe" with the "-u" command line flag which allows anything passed to it to be an argument of the ShellExecute API, which would allow an attacker to execute arbitrary binaries.
This detection also focuses on any uncommon child processes spawned from "Wlrmdr.exe" as a supplement for those that posses "ParentImage" telemetry.

Log source

product: windows
category: process_creation

Detection

selection_parent: # This selection is looking for processes spawned from wlrmdr using the "-u" flag
    ParentImage|endswith: '\wlrmdr.exe'
selection_child_img:
    - Image|endswith: '\wlrmdr.exe'
    - OriginalFileName: 'WLRMNDR.EXE'
selection_child_cli_flags_s:
    CommandLine|contains|windash: '-s '
selection_child_cli_flags_f:
    CommandLine|contains|windash: '-f '
selection_child_cli_flags_t:
    CommandLine|contains|windash: '-t '
selection_child_cli_flags_m:
    CommandLine|contains|windash: '-m '
selection_child_cli_flags_a:
    CommandLine|contains|windash: '-a '
selection_child_cli_flags_u:
    CommandLine|contains|windash: '-u '
filter_main_winlogon:
    ParentImage: 'C:\Windows\System32\winlogon.exe'
filter_main_empty:
    ParentImage:
        - ''
        - '-'
filter_main_null:
    ParentImage: null
condition: selection_parent or (all of selection_child_* and not 1 of filter_main_*)

False positives (as the rule lists them)

Unknown

MITRE ATT&CK ids this rule names

T1218

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_wlrmdr_uncommon_child_process.yml

Sources and licences

SigmaHQ
"Wlrmdr.EXE Uncommon Argument Or Child Process" by frack113, manasmbellani (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_wlrmdr_uncommon_child_process.yml.
Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License
Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Wlrmdr.EXE Uncommon Argument Or Child Process",
entity page, dataset version ref-daad9c388ee0, updated 2025-10-31T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/9cfc00b6-bfb7-49ce-9781-ef78503154bb (accessed 2026-11-03).
Underlying source: SigmaHQ rule 9cfc00b6-bfb7-49ce-9781-ef78503154bb, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.