Windows Steal Authentication Certificates CS Backup

Status: production
Severity: low
Group by: Caller_Domain, action, dest, name, user
Author: Michael Haag, Splunk
Source: github.com/splunk/security_content

The following analytic identifies the backup of the Active Directory Certificate Services (AD CS) store, detected via Event ID 4876. This event is logged when a backup is performed using the CertSrv.msc UI or the CertUtil.exe -BackupDB command. Monitoring this activity is crucial as unauthorized backups can indicate an attempt to steal authentication certificates, which are critical for secure communications. If confirmed malicious, this activity could allow an attacker to impersonate users, escalate privileges, or access sensitive information, severely compromising the security of the environment.

Known false positives

False positives will be generated based on normal certificate store backups. Leave enabled to generate Risk, as this is meant to be an anomaly analytic. If CS backups are not normal, enable as TTP.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1649` Steal or Forge Authentication Certificates

Telemetry coverage

Provider	Record / event type
Security-Auditing	Event ID 4876: Certificate Services backup started.

Rule body

name: Windows Steal Authentication Certificates CS Backup
id: a2f4cc7f-6503-4078-b206-f83a29f408a7
version: 9
creation_date: '2023-02-06'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: Anomaly
description: The following analytic identifies the backup of the Active Directory Certificate Services (AD CS) store, detected via Event ID 4876. This event is logged when a backup is performed using the CertSrv.msc UI or the CertUtil.exe -BackupDB command. Monitoring this activity is crucial as unauthorized backups can indicate an attempt to steal authentication certificates, which are critical for secure communications. If confirmed malicious, this activity could allow an attacker to impersonate users, escalate privileges, or access sensitive information, severely compromising the security of the environment.
data_source:
    - Windows Event Log Security 4876
search: |-
    `wineventlog_security` EventCode=4876
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY dest, name, action,
           Caller_Domain ,Caller_User_Name
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `windows_steal_authentication_certificates_cs_backup_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 128 of first reference.
known_false_positives: False positives will be generated based on normal certificate store backups. Leave enabled to generate Risk, as this is meant to be an anomaly analytic. If CS backups are not normal, enable as TTP.
references:
    - https://specterops.io/wp-content/uploads/sites/3/2022/06/Certified_Pre-Owned.pdf
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: The Active Directory Certiciate Services was backed up on $dest$.
analytic_story:
    - Windows Certificate Services
asset_type: Endpoint
mitre_attack_id:
    - T1649
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: `search`

`wineventlog_security` EventCode=4876

Stage 2: `stats`

| stats count min(_time) as firstTime max(_time) as lastTime
    BY dest, name, action,
       Caller_Domain ,Caller_User_Name

Stage 3: `search`

| `security_content_ctime(firstTime)`

Stage 4: `search`

| `security_content_ctime(lastTime)`

Stage 5: `search`

| `windows_steal_authentication_certificates_cs_backup_filter`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`4876`	`field:"EventID" kind:eq value:"4876"`