PUA - NimScan Execution
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.
Detection logic
selection
- Image|endswith: \NimScan.exe
- Hashes|contains:
- IMPHASH=41BB1C7571B3A724EB83A1D2B96DBB8C
- IMPHASH=B1B6ADACB172795480179EFD18A29549
- IMPHASH=0D1F896DC7642AD8384F9042F30279C2Condition
selectionRaw YAML
title: PUA - NimScan Execution
id: 4fd6b1c7-19b8-4488-97f6-00f0924991a3
status: test
description: |
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.
references:
- https://x.com/cyberfeeddigest/status/1887041526397587859
- https://github.com/elddy/NimScan
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-02-05
tags:
- attack.discovery
- attack.t1046
logsource:
category: process_creation
product: windows
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
falsepositives:
- Legitimate administrator activity
level: mediumFalse positives
- Legitimate administrator activity