Name:Windows Steal Authentication Certificates - ESC1 Authentication id:f0306acf-a6ab-437a-bbc6-8628f8d5c97e version:4 date:2024-11-28 author:Steven Dick status:production type:TTP Description:The following analytic detects when a suspicious certificate with a Subject Alternative Name (SAN) is issued using Active Directory Certificate Services (AD CS) and then immediately used for authentication. This detection leverages Windows Security Event Logs, specifically EventCode 4887, to identify the issuance and subsequent use of the certificate. This activity is significant because improperly configured certificate templates can be exploited for privilege escalation and environment compromise. If confirmed malicious, an attacker could gain unauthorized access, escalate privileges, and potentially compromise the entire environment. Data_source:
-Windows Event Log Security 4887
-Windows Event Log Security 4768
search:`wineventlog_security` EventCode IN (4887) Attributes="*SAN:*upn*" Attributes="*CertificateTemplate:*" | stats count min(_time) as firstTime max(_time) as lastTime values(name) as name values(status) as status values(Subject) as ssl_subject values(SubjectKeyIdentifier) as ssl_hash by Computer, EventCode, Requester, Attributes, RequestId | rex field=Attributes "(?i)CertificateTemplate:(?<object>[^\r\n]+)" | rex field=Attributes "(?i)ccm:(?<req_src>[^\r\n]+)" | rex max_match=10 field=Attributes "(?i)(upn=(?<req_user_1>[^\r\n&]+))" | rex max_match=10 field=Attributes "(?i)(dns=(?<req_dest_1>[^\r\n&]+))" | rex field=Requester "(.+\\\\)?(?<src_user>[^\r\n]+)" | rename Attributes as object_attrs, EventCode as signature_id, name as signature, RequestId as ssl_serial, Requester as ssl_subject_common_name | eval user = lower(coalesce(req_user_1,req_user_2)) | join user [ | search `wineventlog_security` EventCode=4768 CertThumbprint=* | rename TargetUserName as user, Computer as auth_dest, IpAddress as auth_src | fields auth_src,auth_dest,user ] | eval src = upper(coalesce(auth_src,req_src)), dest = upper(coalesce(auth_dest,req_dest_1,req_dest_2)), risk_score = 90 | eval flavor_text = case(signature_id=="4887", "User account [".'user'."] authenticated after a suspicious certificate was issued for it by [".'src_user'."] using certificate request ID: ".'ssl_serial') | fields - req_* auth_* | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_steal_authentication_certificates___esc1_authentication_filter`
how_to_implement:To implement this analytic, enhanced Audit Logging must be enabled on AD CS and within Group Policy Management for CS server. See Page 115 of first reference. Recommend throttle correlation by RequestId/ssl_serial at minimum. known_false_positives:False positives may be generated in environments where administrative users or processes are allowed to generate certificates with Subject Alternative Names for authentication. Sources or templates used in these processes may need to be tuned out for accurate function. References: -https://specterops.io/wp-content/uploads/sites/3/2022/06/Certified_Pre-Owned.pdf -https://github.com/ly4k/Certipy#esc1 -https://pentestlaboratories.com/2021/11/08/threat-hunting-certificate-account-persistence/ drilldown_searches: name:'View the detection results for - "$src$" and "$dest$"' search:'%original_detection_search% | search src = "$src$" dest = "$dest$" src_user = "$src_user$" user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$src$" and "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src$", "$dest$", "$src_user$", "$user$") 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: - 'Windows Certificate Services' - 'Compromised Windows Host' asset_type:Endpoint confidence:90 impact:100 message:Possible AD CS ESC1 authentication on $dest$ mitre_attack_id: - 'T1649' - 'T1550' observable: name:'src' type:'Hostname' - role: - 'Victim' name:'dest' type:'Hostname' - role: - 'Victim' name:'src_user' type:'User' - role: - 'Victim' name:'user' type:'User' - role: - 'Victim' name:'ssl_hash' type:'Other' - role: - 'Attacker' name:'ssl_serial' type:'Other' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Attributes' - 'Computer' - 'EventCode' - 'Requester' - 'RequestId' - 'TargetUserName' - 'Computer' - 'IpAddress' risk_score:90 security_domain:endpoint
