Detectionhighexperimental
MMC Executing Files with Reversed Extensions Using RTLO Abuse
Detects malicious behavior where the MMC utility (`mmc.exe`) executes files with reversed extensions caused by Right-to-Left Override (RLO) abuse, disguising them as document formats.
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Launch
Swachchhanda Shrawan Poudel (Nextron Systems)Created Wed Feb 059cfe4b27-1e56-48b4-b7a8-d46851c91a44windows
Log Source
WindowsProcess Creation
ProductWindows← raw: windows
CategoryProcess Creation← raw: process_creation
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
Detection Logic
Detection Logic2 selectors
detection:
selection_image:
- Image|endswith: '\mmc.exe'
- OriginalFileName: 'MMC.exe'
selection_commandline:
CommandLine|contains: # While looking at these files the prefix of their name will look something like csm.pdf, but in reality it is msc file
- 'cod.msc' # Reversed `.doc`
- 'fdp.msc' # Reversed `.pdf`
- 'ftr.msc' # Reversed `.rtf`
- 'lmth.msc' # Reversed `.html`
- 'slx.msc' # Reversed `.xls`
- 'tdo.msc' # Reversed `.odt`
- 'xcod.msc' # Reversed `.docx`
- 'xslx.msc' # Reversed `.xlsx`
- 'xtpp.msc' # Reversed `.pptx`
condition: all of selection_*False Positives
Legitimate administrative actions using MMC to execute misnamed `.msc` files.
Unconventional but non-malicious usage of RLO or reversed extensions.
MITRE ATT&CK
Rule Metadata
Rule ID
9cfe4b27-1e56-48b4-b7a8-d46851c91a44
Status
experimental
Level
high
Type
Detection
Created
Wed Feb 05
Path
rules/windows/process_creation/proc_creation_win_mmc_rlo_abuse_pattern.yml
Raw Tags
attack.executionattack.t1204.002attack.defense-evasionattack.t1218.014attack.t1036.002