Name:Azure AD Multiple Users Failing To Authenticate From Ip id:94481a6a-8f59-4c86-957f-55a71e3612a6 version:5 date:2024-09-30 author:Mauricio Velazco, Gowthamaraj Rajendran, Splunk status:production type:Anomaly Description:The following analytic detects a single source IP failing to authenticate with 30 unique valid users within 5 minutes in Azure Active Directory. It leverages Azure AD SignInLogs with error code 50126, indicating invalid passwords. This behavior is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges by trying common passwords across many accounts. If confirmed malicious, this activity could lead to unauthorized access, data breaches, or privilege escalation within the Azure AD environment. Data_source:
-Azure Active Directory
search:`azure_monitor_aad` category=SignInLogs properties.status.errorCode=50126 properties.authenticationDetails{}.succeeded=false | rename properties.* as * | bucket span=5m _time | stats count min(_time) as firstTime max(_time) as lastTime dc(user) AS unique_accounts values(user) as user by src_ip | where unique_accounts > 30 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `azure_ad_multiple_users_failing_to_authenticate_from_ip_filter`
how_to_implement:You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase (https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment through an EventHub. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the Signin log category. known_false_positives:A source Ip failing to authenticate with multiple users is not a common for legitimate behavior. References: -https://attack.mitre.org/techniques/T1110/003/ -https://docs.microsoft.com/en-us/security/compass/incident-response-playbook-password-spray -https://www.cisa.gov/uscert/ncas/alerts/aa21-008a -https://docs.microsoft.com/azure/active-directory/reports-monitoring/reference-sign-ins-error-codes drilldown_searches: name:'View the detection results for - "$user$"' search:'%original_detection_search% | search user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Azure Active Directory Account Takeover' asset_type:Azure Active Directory confidence:90 impact:70 message:Source Ip $src_ip$ failed to authenticate with 30 users within 5 minutes. mitre_attack_id: - 'T1586' - 'T1586.003' - 'T1110' - 'T1110.003' - 'T1110.004' observable: name:'user' type:'User' - role: - 'Victim' name:'src_ip' type:'IP Address' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'properties.status.errorCode' - 'category' - 'properties.authenticationDetails' - 'user' - 'user_agent' risk_score:63 security_domain:identity
