CVE-2022-48437 in OpenBSD
Summary
by MITRE • 04/12/2023
An issue was discovered in x509/x509_verify.c in LibreSSL before 3.6.1, and in OpenBSD before 7.2 errata 001. x509_verify_ctx_add_chain does not store errors that occur during leaf certificate verification, and therefore an incorrect error is returned. This behavior occurs when there is an installed verification callback that instructs the verifier to continue upon detecting an invalid certificate.
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Analysis
by VulDB Data Team • 02/10/2025
The vulnerability identified as CVE-2022-48437 represents a critical flaw in the certificate verification process of LibreSSL and OpenBSD systems, specifically within the x509_verify.c module. This issue affects versions prior to 3.6.1 in LibreSSL and before OpenBSD 7.2 errata 001, creating a significant security gap that could undermine the integrity of SSL/TLS connections. The flaw manifests in the x509_verify_ctx_add_chain function which fails to properly store and propagate verification errors that occur during the leaf certificate validation process.
The technical root cause of this vulnerability stems from improper error handling within the certificate verification framework. When an installed verification callback is configured to continue processing even after detecting an invalid certificate, the system incorrectly returns a different error code than what actually occurred during the verification process. This misbehavior creates a situation where security decisions are made based on inaccurate error information, potentially allowing malicious actors to bypass certificate validation mechanisms. The vulnerability is classified under CWE-248 as an "Exception Not Caught" scenario, where errors during certificate validation are not properly captured and handled, leading to incorrect security state reporting.
The operational impact of this vulnerability is substantial, particularly in environments where certificate-based authentication is critical for security. Systems utilizing affected versions of LibreSSL or OpenBSD may continue to accept certificates that should be rejected, creating potential attack vectors for man-in-the-middle attacks or certificate forgery attempts. The flawed error reporting means that administrators and security monitoring systems receive incorrect information about certificate validation failures, potentially masking actual security breaches. This vulnerability directly impacts the core security functionality of SSL/TLS implementations and could enable attackers to exploit the verification process to establish fraudulent connections.
This vulnerability aligns with several ATT&CK techniques including T1552.001 (Credentials in Files) and T1046 (Network Service Scanning) as it could enable attackers to bypass certificate validation and establish unauthorized connections. The issue also relates to T1557 (Adversarial Use of Network Protocols) where compromised verification mechanisms could allow for protocol-level attacks. Organizations using affected systems should prioritize immediate patching to address the error handling deficiency in certificate verification. The recommended mitigation involves upgrading to LibreSSL 3.6.1 or applying the OpenBSD 7.2 errata 001 patch, which properly implements error storage and propagation during leaf certificate verification. Additionally, security teams should conduct thorough audits of certificate validation processes and implement monitoring for anomalous verification behavior that could indicate exploitation attempts.