Azure Alert Suppression Rule Created or Modified

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Azure Alert Suppression Rule Created or Modified

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Identifies the creation of suppression rules in Azure. Suppression rules are a mechanism used to suppress alerts previously identified as false positives or too noisy to be in production. This mechanism can be abused or mistakenly configured, resulting in defense evasions and loss of security visibility.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-azure*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-25m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Cloud
  • Azure
  • Continuous Monitoring
  • SecOps
  • Configuration Audit

Version: 4 (version history)

Added (Elastic Stack release): 8.0.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Austin Songer

Rule license: Elastic License v2

Potential false positives

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Suppression Rules can be created legitimately by a system administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment. Suppression Rules created by unfamiliar users should be investigated. If known behavior is causing false positives, it can be exempted from the rule.

Investigation guide

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Rule query

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event.dataset:azure.activitylogs and azure.activitylogs.operation_name
:"MICROSOFT.SECURITY/ALERTSSUPPRESSIONRULES/WRITE" and event.outcome:
"success"

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 4 (8.4.0 release)
  • Updated query, changed from:

    event.dataset:azure.activitylogs and azure.activitylogs.operation_name
    :"MICROSOFT.SECURITY/ALERTSSUPPRESSIONRULES/WRITE" and event.outcome:
    "success"
Version 2 (8.1.0 release)
  • Formatting only