{"id":"4fd6b1c7-19b8-4488-97f6-00f0924991a3","title":"PUA - NimScan Execution","description":"Detects usage of NimScan, a portscanner utility.\nIn early 2025, adversaries were observed using this utility to scan for open ports on remote hosts in a compromised environment.\nThis rule identifies the execution of NimScan based on the process image name and specific hash values associated with different versions of the tool.\n","author":"Swachchhanda Shrawan Poudel (Nextron Systems)","status":"test","level":"medium","date":"2025-02-05","modified":"","tags":["attack.discovery","attack.t1046"],"technique_ids":["T1046"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Legitimate administrator activity"],"references":["https://x.com/cyberfeeddigest/status/1887041526397587859","https://github.com/elddy/NimScan"],"source_path":"rules/windows/process_creation/proc_creation_win_pua_nimscan.yml","source_sha256":"34e278c5e19e758dc2b4db440a7f1f8764ee6b8e853b649b89bbec9e4e7c550e","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_pua_nimscan.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: PUA - NimScan Execution\nid: 4fd6b1c7-19b8-4488-97f6-00f0924991a3\nstatus: test\ndescription: |\n    Detects usage of NimScan, a portscanner utility.\n    In early 2025, adversaries were observed using this utility to scan for open ports on remote hosts in a compromised environment.\n    This rule identifies the execution of NimScan based on the process image name and specific hash values associated with different versions of the tool.\nreferences:\n    - https://x.com/cyberfeeddigest/status/1887041526397587859\n    - https://github.com/elddy/NimScan\nauthor: Swachchhanda Shrawan Poudel (Nextron Systems)\ndate: 2025-02-05\ntags:\n    - attack.discovery\n    - attack.t1046\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection:\n        - Image|endswith: '\\NimScan.exe' # Other metadata fields such as originalfilename and product were omitted because they were null\n        - Hashes|contains:\n              - 'IMPHASH=41BB1C7571B3A724EB83A1D2B96DBB8C' # v1.0.8\n              - 'IMPHASH=B1B6ADACB172795480179EFD18A29549' # v1.0.6\n              - 'IMPHASH=0D1F896DC7642AD8384F9042F30279C2' # v1.0.4 and v1.0.2\n    condition: selection\nfalsepositives:\n    - Legitimate administrator activity\nlevel: medium\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1046","id":"T1046","name":"Network Service Discovery","page":"techniques/enterprise/T1046/"}],"data_path":"data/detection-rules/4fd6b1c7-19b8-4488-97f6-00f0924991a3.json","kind":"sigma"}