Microsoft 365 Brute Force via Entra ID Sign-Ins

Last updated a month ago on 2025-06-05
Created 10 months ago on 2024-09-06

About

Identifies potential brute-force attacks targeting Microsoft 365 user accounts by analyzing failed sign-in patterns in Microsoft Entra ID Sign-In Logs. This detection focuses on a high volume of failed interactive or non-interactive authentication attempts within a short time window, often indicative of password spraying, credential stuffing, or password guessing. Adversaries may use these techniques to gain unauthorized access to Microsoft 365 services such as Exchange Online, SharePoint, or Teams.
Tags
Domain: CloudDomain: SaaSDomain: IdentityData Source: AzureData Source: Entra IDData Source: Entra ID Sign-in LogsUse 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)

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*

| EVAL
    time_window = DATE_TRUNC(15 minutes, @timestamp),
    user_id = TO_LOWER(azure.signinlogs.properties.user_principal_name),
    ip = source.ip,
    login_error = azure.signinlogs.result_description,
    error_code = azure.signinlogs.properties.status.error_code,
    request_type = TO_LOWER(azure.signinlogs.properties.incoming_token_type),
    app_name = TO_LOWER(azure.signinlogs.properties.app_display_name),
    asn_org = source.`as`.organization.name,
    country = source.geo.country_name,
    user_agent = user_agent.original,
    event_time = @timestamp

| WHERE event.dataset == "azure.signinlogs"
    AND event.category == "authentication"
    AND azure.signinlogs.category IN ("NonInteractiveUserSignInLogs", "SignInLogs")
    AND azure.signinlogs.properties.resource_display_name RLIKE "(.*)365|SharePoint|Exchange|Teams|Office(.*)"
    AND event.outcome == "failure"
    AND error_code != 50053
    AND azure.signinlogs.properties.status.error_code IN (
        50034,  // UserAccountNotFound
        50126,  // InvalidUsernameOrPassword
        50055,  // PasswordExpired
        50056,  // InvalidPassword
        50057,  // UserDisabled
        50064,  // CredentialValidationFailure
        50076,  // MFARequiredButNotPassed
        50079,  // MFARegistrationRequired
        50105,  // EntitlementGrantsNotFound
        70000,  // InvalidGrant
        70008,  // ExpiredOrRevokedRefreshToken
        70043,  // BadTokenDueToSignInFrequency
        80002,  // OnPremisePasswordValidatorRequestTimedOut
        80005,  // OnPremisePasswordValidatorUnpredictableWebException
        50144,  // InvalidPasswordExpiredOnPremPassword
        50135,  // PasswordChangeCompromisedPassword
        50142,  // PasswordChangeRequiredConditionalAccess
        120000, // PasswordChangeIncorrectCurrentPassword
        120002, // PasswordChangeInvalidNewPasswordWeak
        120020  // PasswordChangeFailure
    )
    AND user_id IS NOT NULL AND user_id != ""
    AND user_agent != "Mozilla/5.0 (compatible; MSAL 1.0) PKeyAuth/1.0"

| STATS
    authentication_requirement = VALUES(azure.signinlogs.properties.authentication_requirement),
    client_app_id = VALUES(azure.signinlogs.properties.app_id),
    client_app_display_name = VALUES(azure.signinlogs.properties.app_display_name),
    target_resource_id = VALUES(azure.signinlogs.properties.resource_id),
    target_resource_display_name = VALUES(azure.signinlogs.properties.resource_display_name),
    conditional_access_status = VALUES(azure.signinlogs.properties.conditional_access_status),
    device_detail_browser = VALUES(azure.signinlogs.properties.device_detail.browser),
    device_detail_device_id = VALUES(azure.signinlogs.properties.device_detail.device_id),
    device_detail_operating_system = VALUES(azure.signinlogs.properties.device_detail.operating_system),
    incoming_token_type = VALUES(azure.signinlogs.properties.incoming_token_type),
    risk_state = VALUES(azure.signinlogs.properties.risk_state),
    session_id = VALUES(azure.signinlogs.properties.session_id),
    user_id = VALUES(azure.signinlogs.properties.user_id),
    user_principal_name = VALUES(azure.signinlogs.properties.user_principal_name),
    result_description = VALUES(azure.signinlogs.result_description),
    result_signature = VALUES(azure.signinlogs.result_signature),
    result_type = VALUES(azure.signinlogs.result_type),

    unique_users = COUNT_DISTINCT(user_id),
    user_id_list = VALUES(user_id),
    login_errors = VALUES(login_error),
    unique_login_errors = COUNT_DISTINCT(login_error),
    error_codes = VALUES(error_code),
    unique_error_codes = COUNT_DISTINCT(error_code),
    request_types = VALUES(request_type),
    app_names = VALUES(app_name),
    ip_list = VALUES(ip),
    unique_ips = COUNT_DISTINCT(ip),
    source_orgs = VALUES(asn_org),
    countries = VALUES(country),
    unique_country_count = COUNT_DISTINCT(country),
    unique_asn_orgs = COUNT_DISTINCT(asn_org),
    first_seen = MIN(event_time),
    last_seen = MAX(event_time),
    total_attempts = COUNT()
BY time_window

| EVAL
    duration_seconds = DATE_DIFF("seconds", first_seen, last_seen),
    bf_type = CASE(
        // Many users, relatively few distinct login errors, distributed over multiple IPs (but not too many),
        // and happens quickly. Often bots using leaked credentials.
        unique_users >= 10 AND total_attempts >= 30 AND unique_login_errors <= 3
            AND unique_ips >= 5
            AND duration_seconds <= 600
            AND unique_users > unique_ips,
        "credential_stuffing",

        // One password against many users. Single error (e.g., "InvalidPassword"), not necessarily fast.
        unique_users >= 15 AND unique_login_errors == 1 AND total_attempts >= 15 AND duration_seconds <= 1800,
        "password_spraying",

        // One user targeted repeatedly (same error), OR extremely noisy pattern from many IPs.
        (unique_users == 1 AND unique_login_errors == 1 AND total_attempts >= 30 AND duration_seconds <= 300)
            OR (unique_users <= 3 AND unique_ips > 30 AND total_attempts >= 100),
        "password_guessing",

        // everything else
        "other"
    )

| KEEP
    time_window, bf_type, duration_seconds, total_attempts, first_seen, last_seen,
    unique_users, user_id_list, login_errors, unique_login_errors,
    unique_error_codes, error_codes, request_types, app_names,
    ip_list, unique_ips, source_orgs, countries,
    unique_country_count, unique_asn_orgs,
    authentication_requirement, client_app_id, client_app_display_name,
    target_resource_id, target_resource_display_name, conditional_access_status,
    device_detail_browser, device_detail_device_id, device_detail_operating_system,
    incoming_token_type, risk_state, session_id, user_id,
    user_principal_name, result_description, result_signature, result_type

| WHERE bf_type != "other"

Install detection rules in Elastic Security

Detect Microsoft 365 Brute Force via Entra ID Sign-Ins 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).