{"id":"d95de845-b83c-4a9a-8a6a-4fc802ebf6c0","title":"Suspicious Group And Account Reconnaissance Activity Using Net.EXE","description":"Detects suspicious reconnaissance command line activity on Windows systems using Net.EXE\nCheck if the user that executed the commands is suspicious (e.g. service accounts, LOCAL_SYSTEM)\n","author":"Florian Roth (Nextron Systems), omkar72, @svch0st, Nasreddine Bencherchali (Nextron Systems)","status":"test","level":"medium","date":"2019-01-16","modified":"2023-03-02","tags":["attack.discovery","attack.t1087.001","attack.t1087.002"],"technique_ids":["T1087.001","T1087.002"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Inventory tool runs","Administrative activity"],"references":["https://redcanary.com/blog/how-one-hospital-thwarted-a-ryuk-ransomware-outbreak/","https://thedfirreport.com/2020/10/18/ryuk-in-5-hours/","https://research.nccgroup.com/2022/08/19/back-in-black-unlocking-a-lockbit-3-0-ransomware-attack/"],"source_path":"rules/windows/process_creation/proc_creation_win_net_groups_and_accounts_recon.yml","source_sha256":"9d72f8de7778f0505a080d9ca09b08743b86d8df573d505f580977b4ef8bb3fb","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_net_groups_and_accounts_recon.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Suspicious Group And Account Reconnaissance Activity Using Net.EXE\nid: d95de845-b83c-4a9a-8a6a-4fc802ebf6c0\nstatus: test\ndescription: |\n    Detects suspicious reconnaissance command line activity on Windows systems using Net.EXE\n    Check if the user that executed the commands is suspicious (e.g. service accounts, LOCAL_SYSTEM)\nreferences:\n    - https://redcanary.com/blog/how-one-hospital-thwarted-a-ryuk-ransomware-outbreak/\n    - https://thedfirreport.com/2020/10/18/ryuk-in-5-hours/\n    - https://research.nccgroup.com/2022/08/19/back-in-black-unlocking-a-lockbit-3-0-ransomware-attack/\nauthor: Florian Roth (Nextron Systems), omkar72, @svch0st, Nasreddine Bencherchali (Nextron Systems)\ndate: 2019-01-16\nmodified: 2023-03-02\ntags:\n    - attack.discovery\n    - attack.t1087.001\n    - attack.t1087.002\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection_img:\n        - Image|endswith:\n              - '\\net.exe'\n              - '\\net1.exe'\n        - OriginalFileName:\n              - 'net.exe'\n              - 'net1.exe'\n    # Covers group and localgroup flags\n    selection_group_root:\n        CommandLine|contains:\n            - ' group '\n            - ' localgroup '\n    selection_group_flags:\n        CommandLine|contains:\n            # Add more groups for other languages\n            - 'domain admins'\n            - ' administrator' # Typo without an 'S' so we catch both\n            - ' administrateur' # Typo without an 'S' so we catch both\n            - 'enterprise admins'\n            - 'Exchange Trusted Subsystem'\n            - 'Remote Desktop Users'\n            - 'Utilisateurs du Bureau à distance' # French for \"Remote Desktop Users\"\n            - 'Usuarios de escritorio remoto' # Spanish for \"Remote Desktop Users\"\n            - ' /do' # short for domain\n    filter_group_add:\n        # This filter is added to avoid the potential case where the point is not recon but addition\n        CommandLine|contains: ' /add'\n    # Covers 'accounts' flag\n    selection_accounts_root:\n        CommandLine|contains: ' accounts '\n    selection_accounts_flags:\n        CommandLine|contains: ' /do' # short for domain\n    condition: selection_img and ((all of selection_group_* and not filter_group_add) or all of selection_accounts_*)\nfalsepositives:\n    - Inventory tool runs\n    - Administrative activity\nlevel: medium\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1087.001","id":"T1087.001","name":"Local Account","page":"techniques/enterprise/T1087.001/"},{"key":"enterprise/T1087.002","id":"T1087.002","name":"Domain Account","page":"techniques/enterprise/T1087.002/"}],"data_path":"data/detection-rules/d95de845-b83c-4a9a-8a6a-4fc802ebf6c0.json","kind":"sigma"}