Image Loaded with Invalid Signature

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Identifies binaries that are loaded and with an invalid code signature. This may indicate an attempt to masquerade as a signed binary.

Rule type: eql

Rule indices:

  • logs-endpoint.events.*

Severity: low

Risk score: 21

Runs every: 60m

Searches indices from: now-119m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Defense Evasion
  • Rule Type: BBR
  • Data Source: Elastic Defend

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule query

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library where host.os.type == "windows" and event.action == "load" and
  dll.code_signature.status : ("errorUntrustedRoot", "errorBadDigest", "errorUntrustedRoot") and
  (dll.Ext.relative_file_creation_time <= 500 or dll.Ext.relative_file_name_modify_time <= 500) and
  not startswith~(dll.name, process.name) and
  not dll.path : (
    "?:\\Windows\\System32\\DriverStore\\FileRepository\\*"
  )

Framework: MITRE ATT&CKTM