Base64 Encoding/Decoding Activityedit
Identifies attempts to encode and decode data, a technique adversaries can use to evade detection by host- or network-based security controls.
Rule type: query
Rule indices:
- auditbeat-*
- logs-endpoint.events.*
Severity: low
Risk score: 21
Runs every: 5 minutes
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
Tags:
- Elastic
- Linux
Version: 3 (version history)
Added (Elastic Stack release): 7.8.0
Last modified (Elastic Stack release): 7.9.1
Rule authors: Elastic
Rule license: Elastic License
Potential false positivesedit
Automated tools such as Jenkins may encode or decode files as part of their normal behavior. These events can be filtered by the process executable or username values.
Rule queryedit
event.category:process and event.type:(start or process_started) and process.name:(base64 or base64plain or base64url or base64mime or base64pem)
Threat mappingedit
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
-
Technique:
- Name: Deobfuscate/Decode Files or Information
- ID: T1140
- Reference URL: https://attack.mitre.org/techniques/T1140/
-
Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
-
Technique:
- Name: Obfuscated Files or Information
- ID: T1027
- Reference URL: https://attack.mitre.org/techniques/T1027/
Rule version historyedit
- Version 3 (7.9.1 release)
-
- Formatting only
- Version 2 (7.9.0 release)
-
-
Updated query, changed from:
event.action:(executed or process_started) and process.name:(base64 or base64plain or base64url or base64mime or base64pem)
-