Elastic medium deprecated kql

Deprecated - Azure Entra Sign-in Brute Force Microsoft 365 Accounts by Repeat Source

Identifies potential brute-force attempts against Microsoft 365 user accounts by detecting a high number of failed interactive or non-interactive login attempts within a 30-minute window from a single source. Attackers may attempt to brute force user accounts to gain unauthorized access to Microsoft 365 services via different services such as Exchange, SharePoint, or Teams.

View Source

Detection Logic

from logs-azure.signinlogs*
| WHERE
  event.dataset == "azure.signinlogs"
  and event.category == "authentication"
  and to_lower(azure.signinlogs.properties.resource_display_name) rlike "(.*)365(.*)"
  and azure.signinlogs.category in ("NonInteractiveUserSignInLogs", "SignInLogs")
  and event.outcome != "success"

  // For tuning, review azure.signinlogs.properties.status.error_code
  // https://learn.microsoft.com/en-us/entra/identity-platform/reference-error-codes

// keep only relevant fields
| keep event.dataset, event.category, azure.signinlogs.properties.resource_display_name, azure.signinlogs.category, event.outcome, azure.signinlogs.properties.user_principal_name, source.ip

// Count the number of unique targets per source IP
| stats
  target_count = count_distinct(azure.signinlogs.properties.user_principal_name) by source.ip

// Filter for at least 10 distinct failed login attempts from a single source
| where target_count >= 10

False Positives

⚠ Automated processes that attempt to authenticate using expired credentials or have misconfigured authentication settings may lead to false positives.

Field Validations

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