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Introduction:
Active Directory Certificate Services (AD CS) is a critical component for PKI in Windows environments, but misconfigurations can lead to subtle security flaws. Dangling templates, a quirk where deleted certificate templates remain referenced, allow unauthorized template enabling without standard permissions. This article delves into the mechanics, risks, and remediation of this overlooked issue, leveraging insights from Jake Hildreth’s four-year investigation.
Learning Objectives:
- Understand what dangling templates are and how they arise in AD CS.
- Learn to detect and abuse dangling templates for security testing.
- Implement best practices to mitigate and clean up dangling templates in your environment.
You Should Know:
1. Understanding Dangling Templates and Their Creation
A dangling template occurs when an administrator deletes a certificate template from AD CS without first disabling it, leaving its name “dangling” in the configuration. This happens because the template’s display name is stored separately from its object, and deletion removes the object while the name persists, creating a reusable alias. For security, this can be exploited to enable other templates bypassing typical rights.
Step-by-step guide explaining what this does and how to use it:
– Step 1: Access the AD CS management console on a Windows Server with Enterprise Admin rights. Use PowerShell to list templates:
Get-CATemplate | Format-Table Name, DisplayName, SchemaVersion
– Step 2: Identify a template to delete—e.g., “WebServer”. Instead of disabling it via the GUI or Disable-CATemplate, directly delete it using `certtmpl.msc` or PowerShell:
Remove-CATemplate -Name "WebServer" -Force
– Step 3: Verify the deletion leaves a dangling reference by checking event logs or using ADSI Edit to navigate to CN=Certificate Templates,CN=Public Key Services,CN=Services,CN=Configuration,DC=domain,DC=com. The template name may still appear in UI drop-downs, enabling reuse.
- Security Implications: Abusing Dangling Templates for Unauthorized Access
The core risk is that a dangling template name can be reassigned to a new template without requiring the usual “Write” permissions, as the system treats it as an existing entry. Attackers or insider threats can exploit this to enable malicious templates for certificate issuance, potentially leading to domain escalation if combined with vulnerabilities like ESC1.
Step-by-step guide explaining what this does and how to use it:
– Step 1: As an attacker with low privileges, enumerate dangling templates using PowerShell to query AD CS:
$dangling = Get-CATemplate | Where-Object {$_.Name -eq $null} Hypothetical check; actual detection requires deeper query
– Step 2: Abuse the dangling name by creating a new template with the same display name via certtmpl.msc. For instance, if “WebServer” is dangling, duplicate a template with enhanced rights (e.g., allowing domain authentication) and assign it the “WebServer” name.
– Step 3: Request a certificate using the new template via PowerShell:
Get-Certificate -Template "WebServer" -CertStoreLocation "Cert:\LocalMachine\My"
– Step 4: Use the certificate for authentication, testing for privilege escalation paths. This mimics attacks documented in tools like Certify and SharpDPAPI.
3. Detecting Dangling Templates in Your Environment
Proactive detection is key to preventing abuse. Use native Windows tools and scripts to identify discrepancies between template objects and their display names.
Step-by-step guide explaining what this does and how to use it:
– Step 1: Run a PowerShell script to compare template lists from AD CS and the AD configuration partition. Example:
$caTemplates = Get-CATemplate | Select-Object Name $adTemplates = Get-ADObject -SearchBase "CN=Certificate Templates,CN=Public Key Services,CN=Services,CN=Configuration,DC=domain,DC=com" -Filter | Select-Object Name Compare-Object -ReferenceObject $caTemplates.Name -DifferenceObject $adTemplates.Name
– Step 2: Analyze results for templates in `$caTemplates` missing from $adTemplates, indicating dangling entries. Log findings to a file for audit.
– Step 3: For automated monitoring, integrate this into SIEM tools like Azure Sentinel or Splunk by scheduling the script and alerting on mismatches.
4. Mitigating Dangling Templates: Cleanup and Hardening
Remediation involves removing dangling references and enforcing proper template lifecycle management. This reduces the attack surface for AD CS.
Step-by-step guide explaining what this does and how to use it:
– Step 1: Disable templates before deletion. In PowerShell, disable a template:
Disable-CATemplate -Name "OldTemplate"
– Step 2: After disabling, delete the template object using ADSI Edit or PowerShell with AD module:
Remove-ADObject -Identity "CN=OldTemplate,CN=Certificate Templates,CN=Public Key Services,CN=Services,CN=Configuration,DC=domain,DC=com" -Confirm:$false
– Step 3: Clean up dangling names by re-adding and properly deleting templates. Use `certutil` for low-level fixes:
certutil -dstemplate "DanglingTemplateName"
– Step 4: Implement group policies to restrict template modifications to a small admin group and enable auditing via `AuditPKINegotiate` events in Windows Security logs.
- Using Locksmith 2 for Advanced Detection and Analysis
Locksmith 2, an upcoming tool mentioned by Jake Hildreth, automates dangling template detection. It leverages AD CS APIs to scan for inconsistencies and provide actionable reports.
Step-by-step guide explaining what this does and how to use it:
– Step 1: Download Locksmith 2 from the GitHub repository (link: https://lnkd.in/eS87muhB) once released. Install it on a domain-joined Windows machine with .NET Framework.
– Step 2: Run Locksmith 2 with elevated privileges to scan AD CS:
.\Locksmith2.exe --scan-dangling
– Step 3: Review the generated report listing dangling templates and risk scores. Export data to CSV for further analysis:
.\Locksmith2.exe --export-csv C:\Reports\dangling_templates.csv
– Step 4: Integrate Locksmith 2 into periodic security assessments using Task Scheduler for weekly runs.
- Best Practices for AD CS Management and API Security
Beyond dangling templates, harden AD CS by applying least privilege, monitoring certificate issuance, and securing related APIs. This aligns with MITRE ATT&CK techniques like T1550 (Use Alternate Authentication Material).
Step-by-step guide explaining what this does and how to use it:
– Step 1: Configure certificate template permissions using `certtmpl.msc` to restrict “Enroll” and “Autoenroll” rights to specific security groups. Use PowerShell to audit:
Get-CATemplate | ForEach-Object { Get-Acl "AD:\$($_.Path)" }
– Step 2: Enable CA auditing via `certsrv.msc` under “Properties” > “Auditing” for events like “Issue and Manage Certificate Requests”.
– Step 3: Harden the CA server network exposure by blocking unnecessary ports (e.g., TCP 135, 445) using Windows Firewall:
New-NetFirewallRule -DisplayName "Block CA SMB" -Direction Inbound -Protocol TCP -LocalPort 445 -Action Block
– Step 4: Implement certificate transparency logs and use Azure Key Vault for cloud-integrated PKI to reduce on-prem risks.
7. Vulnerability Exploitation and Mitigation: Real-World Scenarios
Dangling templates can chain with known CVEs like CVE-2022-26923 (AD CS escalation) for domain compromise. Test and patch these vulnerabilities promptly.
Step-by-step guide explaining what this does and how to use it:
– Step 1: Simulate exploitation using public tools like Certify or Rubeus to request certificates via dangling templates. On a Linux attacker machine, use impacket:
python3 certipy.py find -u [email protected] -p password -dc-ip 192.168.1.1
– Step 2: Apply Microsoft patches for AD CS vulnerabilities. Check for updates:
Get-HotFix -Id KB5014754
– Step 3: Use Windows Defender for Identity to detect anomalous certificate requests and set alerts for template modifications.
– Step 4: Conduct red team exercises focusing on certificate abuse and document findings for blue team response playbooks.
What Undercode Say:
- Key Takeaway 1: Dangling templates are a configuration oversight, not a direct CVE, but they lower the barrier for privilege escalation by bypassing template modification permissions.
- Key Takeaway 2: Proactive detection through tools like Locksmith 2 and scripted audits is essential for securing AD CS, as native Windows tools may not reveal these quirks.
Analysis: This issue underscores the complexity of AD CS management, where simple administrative actions can have hidden security consequences. Organizations often prioritize flashy exploits over configuration hygiene, leaving gaps for persistent attackers. By integrating dangling template checks into routine security assessments, teams can reduce risks associated with certificate-based authentication. The lack of a CVE label may lead to underestimation, but in layered defense strategies, fixing such quirks is crucial for preventing domain compromise.
Prediction:
As AD CS remains a target for advanced persistent threats, dangling templates will gain attention in red team toolkits, leading to more automated exploitation scripts. Microsoft may eventually patch this behavior in future Windows Server updates, but until then, third-party tools and community scripts will fill the detection gap. With the rise of hybrid cloud PKI, similar issues may emerge in Azure Key Vault or AWS Certificate Manager, prompting broader research into certificate lifecycle vulnerabilities. Organizations that ignore these nuances risk certificate authority breaches, potentially leading to widespread trust failures in digital identities.
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Reported By: Jakehildreth Hey – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
