IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.
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Elastic Docs ›Elastic Security Solution [7.11] ›Detections and Alerts ›Prebuilt rule reference

Base64 Encoding/Decoding Activity

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Base64 Encoding/Decoding Activity

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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
  • Host
  • Linux
  • Threat Detection
  • Defense Evasion

Version: 6 (version history)

Added (Elastic Stack release): 7.8.0

Last modified (Elastic Stack release): 7.11.2

Rule authors: Elastic

Rule license: Elastic License

Potential false positives

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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 query

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event.category:process and event.type:(start or process_started) and
process.name:(base64 or base64plain or base64url or base64mime or
base64pem)

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 6 (7.11.2 release)
  • Formatting only
Version 5 (7.11.0 release)
  • Formatting only
Version 4 (7.10.0 release)
  • Formatting only
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)
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