Detection: Windows Steal Authentication Certificates Certificate Issued

Updated Date: 2024-05-11 ID: 9b1a5385-0c31-4c39-9753-dc26b8ce64c2 Author: Michael Haag, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic identifies the issuance of a new certificate by Certificate Services - AD CS, detected via Event ID 4887. This event logs the requester user context, DNS hostname of the requesting machine, and the request time. Monitoring this activity is crucial as it can indicate potential misuse of authentication certificates. If confirmed malicious, an attacker could use the issued certificate to impersonate users, escalate privileges, or maintain persistence within the environment. This detection helps in identifying and correlating suspicious certificate-related activities for further investigation.

1`wineventlog_security`  EventCode=4887 
2| stats count min(_time) as firstTime max(_time) as lastTime by dest, name, Requester, action, Attributes, Subject 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)`
5| `windows_steal_authentication_certificates_certificate_issued_filter`

Data Source

Name Platform Sourcetype Source Supported App
Windows Event Log Security 4887 Windows icon 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_certificate_issued_filter search *
windows_steal_authentication_certificates_certificate_issued_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1649 Steal or Forge Authentication Certificates Credential Access
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
APT29

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 Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

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.

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

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A certificate was issued to $dest$. 8 10 80
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

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: 2