{"id":"43fa5350-db63-4b8f-9a01-789a427074e1","title":"Potential Obfuscated Ordinal Call Via Rundll32","description":"Detects execution of \"rundll32\" with potential obfuscated ordinal calls","author":"Nasreddine Bencherchali (Nextron Systems), Swachchhanda Shrawan Poudel (Nextron Systems)","status":"test","level":"medium","date":"2023-05-17","modified":"2025-02-23","tags":["attack.stealth","attack.t1027.010"],"technique_ids":["T1027.010"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Unknown"],"references":["Internal Research","https://www.youtube.com/watch?v=52tAmVLg1KM&t=2070s"],"source_path":"rules/windows/process_creation/proc_creation_win_rundll32_obfuscated_ordinal_call.yml","source_sha256":"a0a4c687a6a17ba4fa01860a0629422cfa37659744cfb52b4fd64376cb5c6e5d","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_rundll32_obfuscated_ordinal_call.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Potential Obfuscated Ordinal Call Via Rundll32\nid: 43fa5350-db63-4b8f-9a01-789a427074e1\nstatus: test\ndescription: Detects execution of \"rundll32\" with potential obfuscated ordinal calls\nreferences:\n    - Internal Research\n    - https://www.youtube.com/watch?v=52tAmVLg1KM&t=2070s\nauthor: Nasreddine Bencherchali (Nextron Systems), Swachchhanda Shrawan Poudel (Nextron Systems)\ndate: 2023-05-17\nmodified: 2025-02-23\ntags:\n    - attack.stealth\n    - attack.t1027.010\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection_img:\n        - Image|endswith: '\\rundll32.exe'\n        - OriginalFileName: 'RUNDLL32.EXE'\n        - CommandLine|contains: 'rundll32'\n    selection_cli:\n        CommandLine|contains:\n            - '#+'\n            - '#-'\n            # ordinal can be represented by adding any number of zeros in front ordinal number, for e.g. 000000024\n            - '#0'\n            # ordinal is 16 bit ordinal, so if you make the number large enough (don't fit in 16 bit space), then it normally wraps around.\n            # for e.g ordinal 24 can be also represented by 65560 (65536+24)\n            - '#655'\n            - '#656'\n    condition: all of selection_*\nfalsepositives:\n    - Unknown\nlevel: medium\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1027.010","id":"T1027.010","name":"Command Obfuscation","page":"techniques/enterprise/T1027.010/"}],"data_path":"data/detection-rules/43fa5350-db63-4b8f-9a01-789a427074e1.json","kind":"sigma"}