PUA - Nimgrab Execution — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: high. Source dates: 2022-08-28 / 2024-11-23.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 315b5209d2577325a2e083aea199d25fc0472161b8e26ab94abb745dfad4cf6b

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: PUA - Nimgrab Execution
id: 74a12f18-505c-4114-8d0b-8448dd5485c6
status: test
description: Detects the usage of nimgrab, a tool bundled with the Nim programming framework and used for downloading files.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/28d190330fe44de6ff4767fc400cc10fa7cd6540/atomics/T1105/T1105.md
author: frack113
date: 2022-08-28
modified: 2024-11-23
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection_name:
        Image|endswith: '\nimgrab.exe'
    selection_hashes:
        Hashes|contains:
            - MD5=2DD44C3C29D667F5C0EF5F9D7C7FFB8B
            - SHA256=F266609E91985F0FE3E31C5E8FAEEEC4FFA5E0322D8B6F15FE69F4C5165B9559
            - IMPHASH=C07FDDD21D123EA9B3A08EEF44AAAC45
    condition: 1 of selection_*
falsepositives:
    - Legitimate use of Nim on a developer systems
level: high

Original YAML and metadata in JSON

False positives

• Legitimate use of Nim on a developer systems

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/28d190330fe44de6ff4767fc400cc10fa7cd6540/atomics/T1105/T1105.md