Name:Windows Multiple Invalid Users Fail To Authenticate Using Kerberos id:001266a6-9d5b-11eb-829b-acde48001122 version:4 date:2024-09-30 author:Mauricio Velazco, Splunk status:production type:TTP Description:The following analytic identifies a source endpoint failing to authenticate with 30 unique invalid domain users using the Kerberos protocol. This detection leverages EventCode 4768, specifically looking for failure code 0x6, indicating the user is not found in the Kerberos database. This activity is significant as it may indicate a Password Spraying attack, where an adversary attempts to gain initial access or elevate privileges. If confirmed malicious, this could lead to unauthorized access or privilege escalation within the Active Directory environment, posing a significant security risk. Data_source:
-Windows Event Log Security 4768
search:`wineventlog_security` EventCode=4768 TargetUserName!=*$ Status=0x6 | bucket span=5m _time | stats dc(TargetUserName) AS unique_accounts values(TargetUserName) as user by _time, IpAddress | where unique_accounts > 30 | `windows_multiple_invalid_users_fail_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 invalid domain users is not a common behavior for legitimate systems. Possible false positive scenarios include but are not limited to vulnerability scanners, multi-user systems and missconfigured systems. References: -https://attack.mitre.org/techniques/T1110/003/ 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' type:'Endpoint' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'EventCode' - 'Status' - 'TargetUserName' - 'IpAddress' risk_score:49 security_domain:endpoint
