Sigma rule: PUA - NimScan Execution

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-f438e2ff70e9, updated 2025-02-05T00:00:00.000Z.

Rule

Title
PUA - NimScan Execution
Status
test
Level
medium
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Date
2025-02-05
File
rules/windows/process_creation/proc_creation_win_pua_nimscan.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects usage of NimScan, a portscanner utility.
In early 2025, adversaries were observed using this utility to scan for open ports on remote hosts in a compromised environment.
This rule identifies the execution of NimScan based on the process image name and specific hash values associated with different versions of the tool.

Log source

product
windows
category
process_creation

Detection

selection:
    - Image|endswith: '\NimScan.exe' # Other metadata fields such as originalfilename and product were omitted because they were null
    - Hashes|contains:
          - 'IMPHASH=41BB1C7571B3A724EB83A1D2B96DBB8C' # v1.0.8
          - 'IMPHASH=B1B6ADACB172795480179EFD18A29549' # v1.0.6
          - 'IMPHASH=0D1F896DC7642AD8384F9042F30279C2' # v1.0.4 and v1.0.2
condition: selection

False positives (as the rule lists them)

  • Legitimate administrator activity

Tags

  • attack.discovery
  • attack.t1046

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_pua_nimscan.yml

Sources and licences

  • SigmaHQ

    "PUA - NimScan Execution" by Swachchhanda Shrawan Poudel (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_pua_nimscan.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: PUA - NimScan Execution",
entity page, dataset version ref-f438e2ff70e9, updated 2025-02-05T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/4fd6b1c7-19b8-4488-97f6-00f0924991a3 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 4fd6b1c7-19b8-4488-97f6-00f0924991a3, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.