Detection rules › Sigma
Decode Base64 Encoded Text
Detects usage of base64 utility to decode arbitrary base64-encoded text
Known false positives
- Legitimate activities
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth |
Telemetry coverage
| Platform | Record / event type |
|---|---|
| Linux | Event ID 1: Process Create |
Rule body
title: Decode Base64 Encoded Text
id: e2072cab-8c9a-459b-b63c-40ae79e27031
status: test
description: Detects usage of base64 utility to decode arbitrary base64-encoded text
references:
- https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1027/T1027.md
author: Daniil Yugoslavskiy, oscd.community
date: 2020-10-19
modified: 2021-11-27
tags:
- attack.stealth
- attack.t1027
logsource:
category: process_creation
product: linux
detection:
selection:
Image|endswith: '/base64'
CommandLine|contains: '-d' # Also covers "--decode"
condition: selection
falsepositives:
- Legitimate activities
level: low
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
Image|endswith: '/base64'
CommandLine|contains: '-d'
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
CommandLine | match |
| field:"CommandLine" kind:match value:"-d" |
Image | ends_with |
| field:"Image" kind:ends_with value:"/base64" |