CVE-2015-4680 in FreeRADIUS
Summary
by MITRE
FreeRADIUS 2.2.x before 2.2.8 and 3.0.x before 3.0.9 does not properly check revocation of intermediate CA certificates.
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Analysis
by VulDB Data Team • 04/14/2019
The vulnerability identified as CVE-2015-4680 affects FreeRADIUS server implementations across versions 2.2.x prior to 2.2.8 and 3.0.x prior to 3.0.9, representing a critical flaw in certificate validation mechanisms that undermines the security of authentication systems relying on certificate-based authentication. This issue stems from inadequate certificate revocation checking for intermediate certificate authorities, creating potential pathways for malicious actors to exploit compromised certificates within the authentication infrastructure.
The technical flaw manifests in the certificate validation process where FreeRADIUS fails to properly verify the revocation status of intermediate CA certificates during the authentication handshake process. This vulnerability falls under the category of certificate validation weakness and aligns with CWE-295 which addresses improper certificate validation. The implementation does not adequately perform certificate revocation checks for intermediate certificates, allowing revoked certificates to be accepted as valid within the authentication chain, potentially enabling unauthorized access to network resources.
The operational impact of this vulnerability is significant for organizations utilizing FreeRADIUS for network access control, particularly in enterprise environments where wireless networks, VPN access, and wired network authentication depend on robust certificate validation. Attackers could potentially exploit this weakness by presenting revoked intermediate certificates that would be accepted by the vulnerable FreeRADIUS server, thereby bypassing authentication controls and gaining unauthorized network access. This vulnerability directly impacts the integrity of the authentication system and could lead to privilege escalation or lateral movement within the network infrastructure.
Organizations should immediately upgrade to FreeRADIUS versions 2.2.8 or 3.0.9 and later to remediate this vulnerability, as these releases include proper certificate revocation checking mechanisms for intermediate CA certificates. Additionally, implementing comprehensive certificate monitoring and management practices, including regular certificate lifecycle management and automated revocation checking, should be enforced. The mitigation strategy should also include network segmentation and monitoring for unauthorized access attempts, as well as regular security assessments of authentication infrastructure to identify potential exploitation vectors. This vulnerability demonstrates the critical importance of maintaining up-to-date security software and implementing robust certificate management practices in network security infrastructure, aligning with security frameworks such as those recommended in the NIST SP 800-57 standard for cryptographic key management and certificate validation protocols.