The following analytic identifies when a new certificate is issued against the Certificate Services - AD CS. By its very nature this is not malicious, but should be tracked and correlated with other events related to certificates being issued. When the CA issues the certificate, it creates EID 4887 'Certificate Services approved a certificate request and issued a certificate". The event supplies the requester user context, the DNS hostname of the machine they requested the certificate from, and the time they requested the certificate. The attributes fields in these event commonly has values for CDC, RMD, and CCM which correspond to Client DC, Request Machine DNS name, and Cert Client Machine, respectively.
- Type: Anomaly
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2023-02-06
- Author: Michael Haag, Splunk
- ID: 9b1a5385-0c31-4c39-9753-dc26b8ce64c2
Kill Chain Phase
- CIS 10
1 2 3 4 5 `wineventlog_security` EventCode=4887 | stats count min(_time) as firstTime max(_time) as lastTime by dest, name, Requester, action, Attributes, Subject | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_steal_authentication_certificates_certificate_issued_filter`
The SPL above uses the following Macros:
windows_steal_authentication_certificates_certificate_issued_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
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.
Known False Positives
False positives will be generated based on normal certificates issued. Leave enabled to generate Risk, as this is meant to be an anomaly analytic.
Associated Analytic Story
|8.0||10||80||A certificate was issued to $dest$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1