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.

Diagram illustrating ESC14 attack vector with vulnerable certificate renewal configuration

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\CRLPeriodUnits

certutil -config "CA_SERVER\CA_NAME" -getreg CA\CRLPeriod

Use Certify to find vulnerable renewal configurations

.\Certify.exe find /vulnerable /renewal

Renew a certificate using certreq

certreq -enroll -q -machine -cert "<Certificate Thumbprint>" Renew

Use 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

Related AD CS Attacks

Explore other attack vectors that target Active Directory Certificate Services:

Diagram illustrating ESC2 attack vector with Enrollment Agent abuse

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.

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Diagram illustrating ESC13 attack vector with vulnerable key archival configuration

ESC13: Vulnerable Key Archival Configuration

High

ESC13 exploits misconfigured key archival settings, potentially allowing unauthorized access to archived private keys, leading to decryption of sensitive data or impersonation attacks.

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Diagram illustrating ESC8 attack vector with NTLM relay to ADCS HTTP endpoints

ESC8: NTLM Relay to ADCS HTTP Endpoints

Critical

ESC8 exploits the ability to relay NTLM authentication to ADCS HTTP endpoints, potentially allowing an attacker to obtain certificates for other users, including domain administrators.

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