CVE-2024-12797: Medium Vulnerability in OpenSSL Raw Public Key Authentication

CVE-2024-12797 is a medium-severity vulnerability that impacts clients using RFC7250 Raw Public Keys (RPKs) for server authentication. The issue arises because when the SSL_VERIFY_PEER verification mode is set, handshakes may not abort as expected if the server is unauthenticated. This flaw puts TLS and DTLS connections at risk of man-in-the-middle attacks, as clients may not recognize that the server authentication has failed.

The vulnerability is particularly concerning because RPKs are disabled by default in both TLS clients and servers. It only manifests when TLS clients explicitly enable RPK usage by the server, which then sends an RPK instead of an X.509 certificate chain. Clients that depend on the handshake to fail when the server's RPK does not match expected public keys may be vulnerable.

If clients enable server-side RPKs, they can detect verification failures by calling SSL_get_verify_result(). Those who take necessary actions based on this result are not affected by this vulnerability. This issue was introduced in the initial implementation of RPK support in OpenSSL 3.2.

Organizations should prioritize patching immediately to mitigate this risk, as unaddressed vulnerabilities can lead to significant security breaches.

Vulnerability Details

This vulnerability allows clients using RFC7250 Raw Public Keys (RPKs) for server authentication to potentially fall prey to man-in-the-middle attacks. The CVSS score of 6.3 indicates a medium severity level, which is critical for organizations relying on secure communications through TLS and DTLS.

The vulnerability was reported on February 11, 2025, and is categorized under CWE-392. The attack vector is classified as NETWORK, with low attack complexity and no required privileges for exploitation. However, user interaction is necessary, as clients need to enable RPK usage explicitly.

Technical Analysis

The root cause of this vulnerability lies in the improper handling of server authentication during the handshake process when RPKs are enabled. Clients expect the handshake to fail if the server's RPK does not match the expected public keys. However, due to the flaw, this does not occur, allowing for potential man-in-the-middle attacks.

The attack complexity is low, as it requires only that the attacker positions themselves in the communication channel between the client and the server. The required privileges for exploitation are none, making it accessible for attackers. User interaction is essential since clients must actively enable RPK usage.

The impact on confidentiality, integrity, and availability is classified as low, as the flaw does not allow the attacker to gain unauthorized access to the client's or server's data, but rather intercept communications without detection.

Risk & Impact Analysis

The risk to organizations includes the possibility of undetected man-in-the-middle attacks, which could compromise sensitive communications and lead to data leaks or unauthorized access. Given that the vulnerability was introduced in OpenSSL 3.2, organizations using this version or later should assess their implementations of RPKs in TLS and DTLS connections.

The urgency for organizations to address this vulnerability is moderate. While it does not affect all installations, those using RPKs must take corrective actions. Regular patching cycles should be updated to include this vulnerability to ensure network security.

Affected Versions

All versions prior to vendor patch. Organizations should ensure they are running OpenSSL version 3.2 or higher, as earlier versions may be vulnerable to this issue.

Mitigation & Remediation

Organizations should implement the following mitigations: patch or upgrade to the latest version of OpenSSL. For those unable to apply patches immediately, disabling RPKs in TLS configurations is strongly recommended. Additionally, clients should validate server certificates correctly by ensuring SSL_get_verify_result() is called and that appropriate actions are taken based on the results.

For further guidance on penetration testing and vulnerability management, organizations can refer to our penetration testing services.

Detection Guidance

To detect potential exploitation of this vulnerability, organizations should monitor logs for anomalies during TLS handshakes. Look for unexpected failures in certificate verification processes and ensure that proper alerting mechanisms are in place for any failures detected during SSL_get_verify_result().

AppSecure Threat Intelligence Insight

CVE-2024-12797 highlights the importance of proper server authentication in the context of emerging technologies such as RPKs. Security teams should evaluate their current implementations of TLS to ensure that they enforce strict verification of server identities to prevent potential man-in-the-middle attacks.

Security teams can strengthen their defenses by following our guidance on penetration testing methodology and implementing a robust vulnerability management program to continuously assess their security posture.

In conclusion, organizations must not underestimate the implications of this vulnerability and should take proactive steps to protect their systems through timely updates and rigorous security practices. Regularly reviewing security protocols will be vital in mitigating risks associated with vulnerabilities like CVE-2024-12797.