CVE-2015-0294 in GnuTLS
Summary
by MITRE
GnuTLS before 3.3.13 does not validate that the signature algorithms match when importing a certificate.
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Analysis
by VulDB Data Team • 12/02/2024
The vulnerability identified as CVE-2015-0294 affects GnuTLS versions prior to 3.3.13 and represents a critical certificate validation flaw that undermines the security of TLS/SSL communications. This issue stems from insufficient validation of signature algorithms during certificate import operations, creating a potential avenue for attackers to manipulate certificate chains and compromise the integrity of encrypted communications. The flaw specifically impacts the certificate verification process within the GnuTLS cryptographic library, which is widely used in various operating systems and applications for implementing secure communications.
The technical nature of this vulnerability lies in the absence of proper signature algorithm matching validation when certificates are imported into the GnuTLS certificate store. When a certificate is processed, the library should verify that the signature algorithm used to sign the certificate matches the expected algorithm for that certificate type. However, in affected versions, this validation step was omitted, allowing certificates with mismatched signature algorithms to be accepted without proper scrutiny. This weakness creates a scenario where an attacker could potentially craft malicious certificates that appear valid to the GnuTLS library but contain altered signature parameters. The vulnerability maps to CWE-327, which addresses the use of weak cryptographic algorithms and improper certificate validation practices. From an attack perspective, this flaw aligns with techniques described in the ATT&CK framework under T1552, specifically targeting credential access through certificate manipulation and trust exploitation.
The operational impact of CVE-2015-0294 extends beyond simple certificate validation failures, potentially enabling man-in-the-middle attacks and certificate forgery scenarios. Systems relying on GnuTLS for secure communications could be vulnerable to attacks where malicious actors present certificates with mismatched signature algorithms that would otherwise be rejected by proper validation mechanisms. This vulnerability particularly affects web servers, email clients, and any application that depends on GnuTLS for certificate verification. The consequences include potential data interception, authentication bypasses, and the ability to impersonate legitimate services. Organizations using affected GnuTLS versions face significant risk to their encrypted communications infrastructure, as the flaw could allow attackers to establish trusted connections with compromised certificates that appear authentic to the client software. The vulnerability also impacts the broader security ecosystem since many applications and operating systems depend on GnuTLS for their cryptographic operations, making this a widespread concern that affects numerous security implementations across different platforms and services.
The recommended mitigation strategy involves immediate upgrading of GnuTLS to version 3.3.13 or later, which contains the necessary fixes to properly validate signature algorithm matching during certificate import operations. System administrators should also implement comprehensive certificate monitoring and validation procedures to detect any potentially compromised certificates that may have been accepted prior to the patch deployment. Additionally, organizations should conduct thorough security assessments of their cryptographic infrastructure to identify any other systems that might be vulnerable to similar certificate validation issues. The fix implemented in GnuTLS 3.3.13 addresses the core validation logic by ensuring that signature algorithms are properly matched against expected values, thereby restoring the integrity of the certificate verification process and preventing attackers from exploiting this weakness to manipulate certificate chains. Security teams should also consider implementing additional monitoring mechanisms to detect unusual certificate validation patterns that might indicate exploitation attempts.