Elastic Security Detection Rules

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

Last updated 2 months ago on 2025-03-20
Created 8 months ago on 2024-09-06

About

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.
Tags
Domain: CloudDomain: SaaSData Source: AzureData Source: Entra IDData Source: Entra ID Sign-inUse Case: Identity and Access AuditUse Case: Threat DetectionTactic: Credential AccessLanguage: esql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Credential Access (TA0006)(opens in a new tab or window)

↳ Brute Force (T1110)(opens in a new tab or window)

False Positive Examples
Automated processes that attempt to authenticate using expired credentials or have misconfigured authentication settings may lead to false positives.
License
Elastic License v2(opens in a new tab or window)

Definition

Integration Pack
Prebuilt Security Detection Rules
Related Integrations

azure(opens in a new tab or window)

Query
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

Install detection rules in Elastic Security

Detect Azure Entra Sign-in Brute Force Microsoft 365 Accounts by Repeat Source in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).