sigmamediumHunting

Linux Base64 Encoded Pipe to Shell

Detects suspicious process command line that uses base64 encoded input for execution with a shell

MITRE ATT&CK

defense-evasion

Detection Query

selection_base64:
  CommandLine|contains: "base64 "
selection_exec:
  - CommandLine|contains:
      - "| bash "
      - "| sh "
      - "|bash "
      - "|sh "
  - CommandLine|endswith:
      - " |sh"
      - "| bash"
      - "| sh"
      - "|bash"
condition: all of selection_*

Author

pH-T (Nextron Systems)

Created

2022-07-26

Data Sources

linuxProcess Creation Events

Platforms

linux

References

Tags

attack.defense-evasionattack.t1140

Raw Content

title: Linux Base64 Encoded Pipe to Shell
id: ba592c6d-6888-43c3-b8c6-689b8fe47337
status: test
description: Detects suspicious process command line that uses base64 encoded input for execution with a shell
references:
    - https://github.com/arget13/DDexec
    - https://www.mandiant.com/resources/blog/barracuda-esg-exploited-globally
author: pH-T (Nextron Systems)
date: 2022-07-26
modified: 2023-06-16
tags:
    - attack.defense-evasion
    - attack.t1140
logsource:
    product: linux
    category: process_creation
detection:
    selection_base64:
        CommandLine|contains: 'base64 '
    selection_exec:
        - CommandLine|contains:
              - '| bash '
              - '| sh '
              - '|bash '
              - '|sh '
        - CommandLine|endswith:
              - ' |sh'
              - '| bash'
              - '| sh'
              - '|bash'
    condition: all of selection_*
falsepositives:
    - Legitimate administration activities
level: medium