Name:Windows Multiple Users Failed To Authenticate Using Kerberos id:3a91a212-98a9-11eb-b86a-acde48001122 version:4 date:2024-09-30 author:Mauricio Velazco, Splunk status:production type:TTP Description:The following analytic identifies a single source endpoint failing to authenticate with 30 unique users using the Kerberos protocol. It leverages EventCode 4771 with Status 0x18, indicating wrong password attempts, and aggregates these events over a 5-minute window. This behavior is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges in an Active Directory environment. If confirmed malicious, this activity could lead to unauthorized access, privilege escalation, and potential compromise of sensitive information. Data_source:
-Windows Event Log Security 4771
search:`wineventlog_security` EventCode=4771 TargetUserName!="*$" Status=0x18 | bucket span=5m _time | stats dc(TargetUserName) AS unique_accounts values(TargetUserName) as user by _time, IpAddress | where unique_accounts > 30 | `windows_multiple_users_failed_to_authenticate_using_kerberos_filter`
how_to_implement:To successfully implement this search, you need to be ingesting Domain Controller and Kerberos events. The Advanced Security Audit policy setting `Audit Kerberos Authentication Service` within `Account Logon` needs to be enabled. known_false_positives:A host failing to authenticate with multiple valid domain users is not a common behavior for legitimate systems. Possible false positive scenarios include but are not limited to vulnerability scanners, missconfigured systems and multi-user systems like Citrix farms. References: -https://attack.mitre.org/techniques/T1110/003/ -https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn319109(v=ws.11) -https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4771 drilldown_searches: name:'View the detection results for - "$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: - 'Active Directory Password Spraying' - 'Active Directory Kerberos Attacks' - 'Volt Typhoon' asset_type:Endpoint confidence:70 impact:70 message:Potential Kerberos based password spraying attack from $IpAddress$ mitre_attack_id: - 'T1110.003' - 'T1110' observable: name:'user' type:'User' - role: - 'Victim' name:'IpAddress' - role: - 'Attacker' type:'Endpoint' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'EventCode' - 'Status' - 'TargetUserName' - 'IpAddress' risk_score:49 security_domain:endpoint
