from logs-o365.audit-*
| mv_expand event.category
| eval
Esql.time_window_date_trunc = date_trunc(5 minutes, @timestamp),
Esql_priv.o365_audit_UserId_lower = to_lower(o365.audit.UserId),
Esql.o365_audit_LogonError = o365.audit.LogonError,
Esql.o365_audit_ExtendedProperties_RequestType_lower = to_lower(o365.audit.ExtendedProperties.RequestType)
| where
event.dataset == "o365.audit" and
event.category == "authentication" and
event.provider in ("AzureActiveDirectory", "Exchange") and
event.action in ("UserLoginFailed", "PasswordLogonInitialAuthUsingPassword") and
Esql.o365_audit_ExtendedProperties_RequestType_lower rlike "(oauth.*||.*login.*)" and
Esql.o365_audit_LogonError != "IdsLocked" and
Esql.o365_audit_LogonError not in (
"EntitlementGrantsNotFound",
"UserStrongAuthEnrollmentRequired",
"UserStrongAuthClientAuthNRequired",
"InvalidReplyTo",
"SsoArtifactExpiredDueToConditionalAccess",
"PasswordResetRegistrationRequiredInterrupt",
"SsoUserAccountNotFoundInResourceTenant",
"UserStrongAuthExpired",
"CmsiInterrupt"
) and
Esql_priv.o365_audit_UserId_lower != "not available" and
o365.audit.Target.Type in ("0", "2", "6", "10")
| stats
Esql.o365_audit_UserId_lower_count_distinct = count_distinct(Esql_priv.o365_audit_UserId_lower),
Esql_priv.o365_audit_UserId_lower_values = values(Esql_priv.o365_audit_UserId_lower),
Esql.o365_audit_LogonError_values = values(Esql.o365_audit_LogonError),
Esql.o365_audit_LogonError_count_distinct = count_distinct(Esql.o365_audit_LogonError),
Esql.o365_audit_ExtendedProperties_RequestType_values = values(Esql.o365_audit_ExtendedProperties_RequestType_lower),
Esql.source_ip_values = values(source.ip),
Esql.source_ip_count_distinct = count_distinct(source.ip),
Esql.source_as_organization_name_values = values(source.`as`.organization.name),
Esql.source_geo_country_name_values = values(source.geo.country_name),
Esql.source_geo_country_name_count_distinct = count_distinct(source.geo.country_name),
Esql.source_as_organization_name_count_distinct = count_distinct(source.`as`.organization.name),
Esql.timestamp_first_seen = min(@timestamp),
Esql.timestamp_last_seen = max(@timestamp),
Esql.event_count = count(*)
by Esql.time_window_date_trunc
| eval
Esql.event_duration_seconds = date_diff("seconds", Esql.timestamp_first_seen, Esql.timestamp_last_seen),
Esql.brute_force_type = case(
Esql.o365_audit_UserId_lower_count_distinct >= 15 and Esql.o365_audit_LogonError_count_distinct == 1 and Esql.event_count >= 10 and Esql.event_duration_seconds <= 1800, "password_spraying",
Esql.o365_audit_UserId_lower_count_distinct >= 8 and Esql.event_count >= 15 and Esql.o365_audit_LogonError_count_distinct <= 3 and Esql.source_ip_count_distinct <= 5 and Esql.event_duration_seconds <= 600, "credential_stuffing",
Esql.o365_audit_UserId_lower_count_distinct == 1 and Esql.o365_audit_LogonError_count_distinct == 1 and Esql.event_count >= 20 and Esql.event_duration_seconds <= 300, "password_guessing",
"other"
)
| keep
Esql.time_window_date_trunc,
Esql.o365_audit_UserId_lower_count_distinct,
Esql_priv.o365_audit_UserId_lower_values,
Esql.o365_audit_LogonError_values,
Esql.o365_audit_LogonError_count_distinct,
Esql.o365_audit_ExtendedProperties_RequestType_values,
Esql.source_ip_values,
Esql.source_ip_count_distinct,
Esql.source_as_organization_name_values,
Esql.source_geo_country_name_values,
Esql.source_geo_country_name_count_distinct,
Esql.source_as_organization_name_count_distinct,
Esql.timestamp_first_seen,
Esql.timestamp_last_seen,
Esql.event_duration_seconds,
Esql.event_count,
Esql.brute_force_type
| where Esql.brute_force_type != "other"
Install detection rules in Elastic Security
Detect Potential Microsoft 365 User Account Brute Force 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).