Python One-Liners with Base64 Decoding - Linux — Sigma Rule

Rule metadata and linked tags

Author: Hugh Ryan (HueCodes), Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2026-03-09 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 4ea767c3ad37790390b5832da7cca1174a0ae09e1065a41c9fb21ca63bb48480

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: Python One-Liners with Base64 Decoding - Linux
id: 55e862a8-dd9c-4651-807a-f21fcad56716
related:
    - id: 50a0aa3d-ab16-4594-a8aa-5145a6e6792b
      type: similar
status: experimental
description: |
    Detects the use of Python's base64 decoding functions in command line executions on Linux systems.
    Malicious scripts often use python one-liners to decode and execute base64-encoded payloads, which is a common technique for obfuscation and evasion.
references:
    - https://docs.python.org/3/library/base64.html
    - https://www.virustotal.com/gui/file/bc43e925d7b4b74319f6e74e836a96f1997ba404e14ac566cf12a21e9da463db/behavior
    - https://cloud.google.com/blog/topics/threat-intelligence/cybercriminals-weaponize-fake-ai-websites
author: Hugh Ryan (HueCodes), Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2026-03-09
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059.006
    - attack.t1027.010
logsource:
    category: process_creation
    product: linux
detection:
    selection_img:
        Image|contains: '/python'
    selection_cli:
        CommandLine|contains|all:
            - 'import'
            - 'base64'
            - ' -c'
        CommandLine|contains:
            - '.decode'
            - 'b16decode'
            - 'b32decode'
            - 'b32hexdecode'
            - 'b64decode'
            - 'b85decode'
            - 'z85decode'
    condition: all of selection_*
falsepositives:
    - Legitimate use of Python for decoding data, which is uncommon in typical enterprise environments but possible in development or data analysis contexts.
level: high

Original YAML and metadata in JSON

False positives

• Legitimate use of Python for decoding data, which is uncommon in typical enterprise environments but possible in development or data analysis contexts.

Source references

• https://docs.python.org/3/library/base64.html
• https://www.virustotal.com/gui/file/bc43e925d7b4b74319f6e74e836a96f1997ba404e14ac566cf12a21e9da463db/behavior
• https://cloud.google.com/blog/topics/threat-intelligence/cybercriminals-weaponize-fake-ai-websites