{"id":"9cfe4b27-1e56-48b4-b7a8-d46851c91a44","title":"MMC Executing Files with Reversed Extensions Using RTLO Abuse","description":"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.","author":"Swachchhanda Shrawan Poudel (Nextron Systems)","status":"experimental","level":"high","date":"2025-02-05","modified":"","tags":["attack.execution","attack.stealth","attack.t1204.002","attack.t1218.014","attack.t1036.002"],"technique_ids":["T1036.002","T1204.002","T1218.014"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Legitimate administrative actions using MMC to execute misnamed `.msc` files.","Unconventional but non-malicious usage of RLO or reversed extensions."],"references":["https://www.unicode.org/versions/Unicode5.2.0/ch02.pdf","https://en.wikipedia.org/wiki/Right-to-left_override","https://tria.ge/241015-l98snsyeje/behavioral2"],"source_path":"rules/windows/process_creation/proc_creation_win_mmc_rlo_abuse_pattern.yml","source_sha256":"6917f7c0e6039b4f5fd16f7a643f87e66488451279f6e6543902d7036c03277a","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_mmc_rlo_abuse_pattern.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: MMC Executing Files with Reversed Extensions Using RTLO Abuse\nid: 9cfe4b27-1e56-48b4-b7a8-d46851c91a44\nstatus: experimental\ndescription: 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.\nreferences:\n    - https://www.unicode.org/versions/Unicode5.2.0/ch02.pdf\n    - https://en.wikipedia.org/wiki/Right-to-left_override\n    - https://tria.ge/241015-l98snsyeje/behavioral2\nauthor: Swachchhanda Shrawan Poudel (Nextron Systems)\ndate: 2025-02-05\ntags:\n    - attack.execution\n    - attack.stealth\n    - attack.t1204.002\n    - attack.t1218.014\n    - attack.t1036.002\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection_image:\n        - Image|endswith: '\\mmc.exe'\n        - OriginalFileName: 'MMC.exe'\n    selection_commandline:\n        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\n            - 'cod.msc'  # Reversed `.doc`\n            - 'fdp.msc'  # Reversed `.pdf`\n            - 'ftr.msc'  # Reversed `.rtf`\n            - 'lmth.msc'  # Reversed `.html`\n            - 'slx.msc'  # Reversed `.xls`\n            - 'tdo.msc'  # Reversed `.odt`\n            - 'xcod.msc'  # Reversed `.docx`\n            - 'xslx.msc'  # Reversed `.xlsx`\n            - 'xtpp.msc'  # Reversed `.pptx`\n    condition: all of selection_*\nfalsepositives:\n    - Legitimate administrative actions using MMC to execute misnamed `.msc` files.\n    - Unconventional but non-malicious usage of RLO or reversed extensions.\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1036.002","id":"T1036.002","name":"Right-to-Left Override","page":"techniques/enterprise/T1036.002/"},{"key":"enterprise/T1204.002","id":"T1204.002","name":"Malicious File","page":"techniques/enterprise/T1204.002/"},{"key":"enterprise/T1218.014","id":"T1218.014","name":"MMC","page":"techniques/enterprise/T1218.014/"}],"data_path":"data/detection-rules/9cfe4b27-1e56-48b4-b7a8-d46851c91a44.json","kind":"sigma"}