Suspicious Curl Change User Agents - Linux — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-09-15 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: fe850c317deca520d12ce3e53746f4ecedb03bf5ff65919764de1eea9203f711

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: Suspicious Curl Change User Agents - Linux
id: b86d356d-6093-443d-971c-9b07db583c68
related:
    - id: 3286d37a-00fd-41c2-a624-a672dcd34e60
      type: derived
status: test
description: Detects a suspicious curl process start on linux with set useragent options
references:
    - https://curl.se/docs/manpage.html
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-15
tags:
    - attack.command-and-control
    - attack.t1071.001
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/curl'
        CommandLine|contains:
            - ' -A '
            - ' --user-agent '
    condition: selection
falsepositives:
    - Scripts created by developers and admins
    - Administrative activity
level: medium

Original YAML and metadata in JSON

False positives

• Scripts created by developers and admins
• Administrative activity

Source references

• https://curl.se/docs/manpage.html