CVE-2022-25640 in wolfSSL
Summary
by MITRE • 02/24/2022
In wolfSSL before 5.2.0, a TLS 1.3 server cannot properly enforce a requirement for mutual authentication. A client can simply omit the certificate_verify message from the handshake, and never present a certificate.
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Analysis
by VulDB Data Team • 02/26/2022
The vulnerability identified as CVE-2022-25640 affects wolfSSL versions prior to 5.2.0 and represents a critical flaw in the implementation of TLS 1.3 mutual authentication mechanisms. This issue specifically impacts TLS 1.3 servers that are configured to require client certificate authentication as part of their security posture. The vulnerability stems from an improper enforcement of the certificate verification process during the TLS handshake, creating a fundamental weakness that allows malicious clients to bypass mandatory client authentication requirements.
The technical flaw manifests in the server's failure to properly validate the presence of the certificate_verify message within the TLS 1.3 handshake sequence. In a properly functioning mutual authentication scenario, the TLS 1.3 protocol mandates that clients must present a certificate_verify message as part of the handshake process to prove possession of the private key corresponding to their certificate. However, wolfSSL versions before 5.2.0 fail to enforce this requirement, allowing clients to omit this critical message entirely. This omission effectively nullifies the mutual authentication mechanism, enabling attackers to establish secure connections without providing the required client certificate.
From an operational impact perspective, this vulnerability fundamentally undermines the security model of systems relying on mutual TLS authentication. Organizations that configure their servers to require client certificates for access control or identity verification are left with a false sense of security, as the vulnerability allows unauthorized parties to bypass these security controls. The implications extend beyond simple access control breaches, as this weakness can enable man-in-the-middle attacks, unauthorized data access, and potential privilege escalation within systems that depend on mutual authentication for security boundaries. The flaw affects any system where wolfSSL is used as the TLS implementation and mutual authentication is enabled, making it particularly concerning for enterprise environments, financial institutions, and any organization requiring strong client authentication.
The vulnerability aligns with CWE-310, which addresses cryptographic weakness, and specifically relates to improper certificate validation within TLS implementations. From an ATT&CK framework perspective, this weakness maps to techniques involving credential access and privilege escalation, as adversaries can exploit this flaw to bypass authentication mechanisms without proper credentials. The vulnerability also intersects with T1552, which covers credentials in files, and T1078, which addresses valid accounts, as the flaw enables unauthorized access through the bypass of legitimate authentication mechanisms. Organizations should immediately upgrade to wolfSSL version 5.2.0 or later to address this vulnerability, as the fix ensures proper enforcement of the certificate_verify message requirement during TLS 1.3 handshakes. Additional mitigations may include implementing network-level access controls, monitoring for anomalous handshake patterns, and conducting thorough security assessments of systems utilizing mutual TLS authentication to identify potential exploitation of this weakness.