Base16 or Base32 Encoding/Decoding Activity

edit

Adversaries may encode/decode data in an attempt 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: 7 (version history)

Added (Elastic Stack release): 7.8.0

Last modified (Elastic Stack release): 7.12.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

edit

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

edit
event.category:process and event.type:(start or process_started) and
process.name:(base16 or base32 or base32plain or base32hex)

Threat mapping

edit

Framework: MITRE ATT&CKTM

Rule version history

edit
Version 7 (7.12.0 release)
  • Formatting only
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:(base16 or
    base32 or base32plain or base32hex)