CVE-2023-3446 Explained : Impact and Mitigation

This CVE-2023-3446 affects applications using OpenSSL and could potentially lead to a Denial of Service attack due to excessively long Diffie-Hellman (DH) keys or parameters causing slow performance. It was published on July 19, 2023.

Understanding CVE-2023-3446

This vulnerability impacts applications that employ the functions DH_check(), DH_check_ex(), or EVP_PKEY_param_check() to validate DH keys or parameters, resulting in significant delays. The issue arises when applying very large modulus values for DH parameters obtained from untrusted sources, potentially leading to a Denial of Service attack.

What is CVE-2023-3446?

The CVE-2023-3446 vulnerability in OpenSSL revolves around slow performance caused by checking excessively long DH keys and parameters, affecting the functionality of certain OpenSSL functions and command line applications.

The Impact of CVE-2023-3446

Applications utilizing the affected functions to examine DH keys or parameters obtained from untrusted sources may face extended processing times, making them susceptible to a Denial of Service attack. While the OpenSSL SSL/TLS implementation remains unaffected, specific OpenSSL command line applications may be vulnerable if utilized with particular options.

Technical Details of CVE-2023-3446

A DH key or DH parameters obtained from suspicious origins may trigger a significant slowdown in certain OpenSSL functions, potentially leading to a Denial of Service scenario.

Vulnerability Description

The vulnerability is triggered when applications use DH_check(), DH_check_ex(), or EVP_PKEY_param_check() to validate DH keys or parameters, with particularly large modulus values causing performance issues.

Affected Systems and Versions

OpenSSL versions 1.0.2, 1.1.1, 3.0.0, and 3.1.0 are affected by this vulnerability. Specifically, versions less than 1.0.2zi, 1.1.1v, 3.0.10, and 3.1.2 are susceptible to this issue.

Exploitation Mechanism

An attacker could exploit this vulnerability by providing DH keys or parameters with excessively large modulus values from untrusted sources, leading to extended processing times and potentially a Denial of Service attack.

Mitigation and Prevention

To safeguard against the CVE-2023-3446 vulnerability, immediate actions and long-term security measures are recommended.

Immediate Steps to Take

Apply the relevant patches provided by OpenSSL through the git commit links.
Consider limiting exposure by reviewing and validating DH keys and parameters from trusted sources only.

Long-Term Security Practices

Regularly update OpenSSL to the latest secure version to mitigate known vulnerabilities.
Implement secure coding practices and validate input parameters to prevent similar issues in the future.

Patching and Updates

Ensure that affected systems are patched with the fixes provided by OpenSSL to address the performance impact of checking DH keys and parameters. Stay informed about security advisories and updates to maintain the security of your systems.