ID | Technique | Tactic |
---|---|---|
T1649 | Steal or Forge Authentication Certificates | Credential Access |
Detection: Windows Steal Authentication Certificates - ESC1 Abuse
Description
The following analytic detects when a new certificate is requested or granted against Active Directory Certificate Services (AD CS) using a Subject Alternative Name (SAN). It leverages Windows Security Event Codes 4886 and 4887 to identify these actions. 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 elevated privileges or persist within the environment, potentially leading to unauthorized access to sensitive information and further exploitation.
Search
1`wineventlog_security` EventCode IN (4886,4887) Attributes="*SAN:*upn*" Attributes="*CertificateTemplate:*"
2| 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
3| `security_content_ctime(firstTime)`
4| `security_content_ctime(lastTime)`
5| fillnull
6| rex field=Attributes "(?i)CertificateTemplate:(?<object>[^\r\n]+)"
7| rex field=Attributes "(?i)ccm:(?<req_src>[^\r\n]+)"
8| rex max_match=10 field=Attributes "(?i)(upn=(?<req_user_1>[^\r\n&]+))"
9| rex max_match=10 field=Attributes "(?i)(dns=(?<req_dest_1>[^\r\n&]+))"
10| rex field=Requester "(.+\\\\)?(?<src_user>[^\r\n]+)"
11| eval flavor_text = case(EventCode=="4886","A suspicious certificate was requested using request ID: ".'RequestId',EventCode=="4887", "A suspicious certificate was issued using request ID: ".'RequestId'.". To revoke this certifacte use this request ID or the SSL fingerprint [".'ssl_hash'."]"), dest = upper(coalesce(req_dest_1,req_dest_2)), src = upper(coalesce(req_src,Computer))
12| fields - req_*
13| rename Attributes as object_attrs, EventCode as signature_id, name as signature, RequestId as ssl_serial, Requester as ssl_subject_common_name
14| `windows_steal_authentication_certificates___esc1_abuse_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Windows Event Log Security 4886 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Security' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
windows_steal_authentication_certificates___esc1_abuse_filter | search * |
windows_steal_authentication_certificates___esc1_abuse_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
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. Sources or templates used in these processes may need to be tuned out for accurate function.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Possible AD CS ESC1 activity by $src_user$ - $flavor_text$ | 60 | 100 | 60 |
References
-
https://specterops.io/wp-content/uploads/sites/3/2022/06/Certified_Pre-Owned.pdf
-
https://pentestlaboratories.com/2021/11/08/threat-hunting-certificate-account-persistence/
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | XmlWinEventLog:Security |
XmlWinEventLog |
Integration | ✅ Passing | Dataset | XmlWinEventLog:Security |
XmlWinEventLog |
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 3