ESC14: Vulnerable Certificate Renewal Configuration
High
ESC14 exploits misconfigured certificate renewal settings, allowing attackers to renew compromised certificates or maintain long-term access to sensitive resources.
Warning: The information provided here is for educational purposes only. Always ensure you have proper authorization before testing these attacks in any environment.
Attack Details
ESC14 targets vulnerabilities in the certificate renewal process within AD CS. When renewal policies are not properly configured, attackers can potentially renew compromised certificates, maintaining their unauthorized access for extended periods. This makes it challenging to detect and respond to security incidents effectively.
Learn more about AD CS defense strategies to protect against this and other attacks.
Impact
- Prolonged unauthorized access to sensitive resources
- Difficulty in detecting and revoking compromised certificates
- Potential for long-term persistence in the network
- Increased challenge in incident response and recovery
Exploitation Steps
- Identify vulnerabilities in certificate renewal configurations
- Obtain a valid certificate through legitimate or illegitimate means
- Exploit weak renewal policies to maintain access beyond intended certificate lifetime
- Use renewed certificates to maintain long-term unauthorized access
Penetration Testing Considerations
When conducting AD CS penetration testing, consider the following aspects specific to ESC14: Vulnerable Certificate Renewal Configuration:
- Identify vulnerable certificate templates and misconfigurations
- Assess the potential impact on the overall AD CS security
- Evaluate the effectiveness of existing security controls
- Test for the ability to exploit this vulnerability in the target environment
- Document findings and provide actionable remediation steps
Command Examples
Enumerate Vulnerable Configurations
certutil -v -template | findstr /i "msPKI-Cert-Template-OID" /c:"Renewal Period"certutil -config "CA_SERVER\CA_NAME" -getreg CA\CRLPeriodUnitscertutil -config "CA_SERVER\CA_NAME" -getreg CA\CRLPeriodUse Certify to find vulnerable renewal configurations
.\Certify.exe find /vulnerable /renewalRenew a certificate using certreq
certreq -enroll -q -machine -cert "<Certificate Thumbprint>" RenewUse PowerShell to renew a certificate
$cert = Get-ChildItem Cert:\LocalMachine\My | Where-Object {$_.Subject -eq "CN=TargetCertificate"}Get-Certificate -Template "User" -CertStoreLocation Cert:\LocalMachine\My -Url ldap: -Credential (Get-Credential)Detection
- Implement comprehensive logging for all certificate renewal activities
- Monitor for unusual patterns in certificate renewal requests
- Regularly audit certificate lifetimes and renewal histories
- Implement alerting for certificate renewals outside of expected parameters
- Conduct periodic reviews of certificate renewal policies and practices
Event IDs
- 4886: Certificate Services approved a certificate request
- 4887: Certificate Services denied a certificate request
- 4890: The certificate manager settings for Certificate Services changed
- 5136: A directory service object was modified (for monitoring renewal policy changes)
Mitigation and AD CS Security Best Practices
To mitigate ESC14: Vulnerable Certificate Renewal Configuration and enhance overall AD CS security, consider implementing the following measures:
- Implement strict certificate renewal policies
- Regular audit of certificate lifetimes and renewal processes
- Implement strong authentication for certificate renewal requests
- Use short-lived certificates to limit the impact of compromised credentials
- Implement automated certificate lifecycle management
- Regularly conduct AD CS penetration testing to identify and address vulnerabilities
- Implement the principle of least privilege across your AD CS infrastructure
- Maintain up-to-date documentation of your AD CS configuration and security policies
References
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Related AD CS Attacks
Explore other attack vectors that target Active Directory Certificate Services:
ESC1: Misconfigured Certificate Templates
Critical
ESC1 exploits overly permissive enrollment rights in certificate templates, allowing low-privileged users to enroll in certificates that can be used for authentication, potentially leading to privilege escalation.
ESC2: Misconfigured Enrollment Agent Templates
High
ESC2 abuses misconfigured Enrollment Agent templates, allowing an attacker to request certificates on behalf of other users, potentially leading to privilege escalation and unauthorized access.
ESC6: ADCS Backup Extraction
Critical
ESC6 involves extracting and abusing ADCS backups to gain unauthorized access to the CA's private keys, potentially allowing an attacker to issue any certificate or decrypt intercepted communications.