Detection rules › Sigma
Linux Base64 Encoded Pipe to Shell
Detects suspicious process command line that uses base64 encoded input for execution with a shell
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1140 Deobfuscate/Decode Files or Information |
Event coverage
| Provider | Event |
|---|---|
| Sysmon-for-Linux | Event ID 1 |
Rule body yaml
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.stealth
- 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
Stages and Predicates
Stage 0: condition
all of selection_*Stage 1: selection_base64
selection_base64:
CommandLine|contains: 'base64 '
Stage 2: selection_exec
selection_exec:
- CommandLine|contains:
- '| bash '
- '| sh '
- '|bash '
- '|sh '
- CommandLine|endswith:
- ' |sh'
- '| bash'
- '| sh'
- '|bash'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CommandLine | ends_with |
|
CommandLine | match |
|