CVE-2014-8155 in GnuTLS
Summary
by MITRE
GnuTLS before 2.9.10 does not verify the activation and expiration dates of CA certificates, which allows man-in-the-middle attackers to spoof servers via a certificate issued by a CA certificate that is (1) not yet valid or (2) no longer valid.
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Analysis
by VulDB Data Team • 06/12/2022
The vulnerability described in CVE-2014-8155 represents a critical flaw in the GnuTLS cryptographic library that affects versions prior to 2.9.10. This issue stems from the library's failure to properly validate certificate validity periods, specifically the activation and expiration dates of Certificate Authority certificates. The flaw creates a significant security gap that enables malicious actors to conduct successful man-in-the-middle attacks by exploiting certificates that should be considered invalid due to their temporal status.
The technical root cause of this vulnerability lies in the certificate validation process within GnuTLS where the system does not enforce proper date checking for CA certificates. When a certificate authority issues a certificate, it must be valid within the current time frame for the certificate chain to be trusted. However, GnuTLS before version 2.9.10 failed to verify that the CA certificate was actually active and valid at the time of certificate validation. This oversight allows attackers to use certificates that are either not yet valid (future-dated) or no longer valid (expired) to establish fraudulent secure connections.
The operational impact of this vulnerability is severe and directly affects the integrity of secure communications. Attackers can exploit this weakness by obtaining or generating certificates that fall outside the valid date range but still manage to pass the validation checks due to the missing date verification. This enables them to impersonate legitimate servers and intercept or modify encrypted communications between clients and servers. The vulnerability particularly affects systems that rely on GnuTLS for SSL/TLS implementations, including web servers, email servers, and other network services that require secure communication channels.
This vulnerability maps directly to CWE-297, which describes "Improper Validation of Certificate with Host Name Mismatch," and more specifically to CWE-310, which covers "Cryptographic Issues." The flaw also aligns with ATT&CK technique T1573.002, which involves securing communication channels through encryption, and T1046, which covers network service scanning that can be used to identify vulnerable systems. The weakness essentially undermines the fundamental trust model of public key infrastructure by allowing certificates to be accepted even when they should be rejected based on their temporal validity.
Organizations affected by this vulnerability should prioritize immediate patching of all systems running GnuTLS versions prior to 2.9.10. The remediation process involves upgrading to version 2.9.10 or later, which includes proper date validation for CA certificates. Additionally, system administrators should conduct comprehensive audits of all certificate deployments to identify and revoke any certificates that may have been compromised due to this vulnerability. Network monitoring should be enhanced to detect unusual certificate validation patterns, and security teams should implement continuous vulnerability assessment procedures to identify similar issues in other cryptographic libraries and systems. The fix ensures that certificate chains properly validate both the certificate's temporal validity and the trust relationship established through the CA certificate's active status.