Microsoft 365 Exchange Safe Attachment Rule Disabled

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Microsoft 365 Exchange Safe Attachment Rule Disabled

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Identifies when a safe attachment rule is disabled in Microsoft 365. Safe attachment rules can extend malware protections to include routing all messages and attachments without a known malware signature to a special hypervisor environment. An adversary or insider threat may disable a safe attachment rule to exfiltrate data or evade defenses.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-o365*

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Cloud
  • Data Source: Microsoft 365
  • Use Case: Configuration Audit
  • Tactic: Defense Evasion

Version: 102

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Rule query

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event.dataset:o365.audit and event.provider:Exchange and event.category:web and event.action:"Disable-SafeAttachmentRule" and event.outcome:success

Framework: MITRE ATT&CKTM