CVE-2011-2014 in Windows
Summary
by MITRE
The LDAP over SSL (aka LDAPS) implementation in Active Directory, Active Directory Application Mode (ADAM), and Active Directory Lightweight Directory Service (AD LDS) in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 does not examine Certificate Revocation Lists (CRLs), which allows remote authenticated users to bypass intended certificate restrictions and access Active Directory resources by leveraging a revoked X.509 certificate for a domain account, aka "LDAPS Authentication Bypass Vulnerability."
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability described in CVE-2011-2014 represents a critical weakness in the secure communication protocols implemented within Microsoft's directory services infrastructure. This flaw specifically affects the LDAP over SSL (LDAPS) implementation across multiple Windows operating systems and server versions, creating a significant security gap that undermines the integrity of authentication mechanisms. The vulnerability stems from the failure of the system to properly validate certificate revocation status during the LDAPS authentication process, allowing malicious actors to exploit this weakness for unauthorized access to directory resources.
The technical root cause of this vulnerability lies in the absence of Certificate Revocation List (CRL) checking within the LDAPS implementation of Active Directory services. When a client establishes an LDAPS connection to a domain controller, the system should verify that the presented X.509 certificate has not been revoked by checking against the appropriate CRL. However, Microsoft's implementation fails to perform this crucial validation step, enabling attackers to present revoked certificates and still gain successful authentication. This bypass occurs because the system accepts certificates that have been formally revoked by certificate authorities, effectively nullifying the security controls designed to prevent access with compromised credentials.
The operational impact of this vulnerability extends beyond simple authentication bypass, as it fundamentally compromises the security posture of organizations relying on LDAPS for directory services. Attackers who can authenticate using revoked certificates gain access to all directory resources available to the compromised account, potentially leading to privilege escalation, data exfiltration, and lateral movement within the network. This vulnerability particularly affects environments where LDAPS is used for secure authentication, making it a prime target for attackers seeking to exploit the trust relationships inherent in Active Directory infrastructure. The risk is amplified because the vulnerability affects multiple Windows versions and server platforms, creating widespread potential for exploitation across enterprise environments.
Organizations affected by this vulnerability should implement immediate mitigations including enabling proper CRL checking, deploying certificate management solutions, and ensuring that revoked certificates are promptly removed from service. The vulnerability aligns with CWE-295, which specifically addresses improper certificate validation, and represents a clear violation of the principle of least privilege in authentication systems. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and privilege escalation, as it allows attackers to leverage compromised certificates for unauthorized access to directory services. Microsoft released patches addressing this issue, but organizations must also consider implementing additional security controls such as monitoring for unusual authentication patterns and ensuring that certificate lifecycle management processes are properly enforced to prevent exploitation of similar vulnerabilities in the future.