A potential security vulnerability, CVE-2024-30171, has been discovered in the Bouncy Castle Java TLS API and JSSE Provider versions before 1.78. This vulnerability is due to timing-based leakage that may happen in RSA-based handshakes because of the way exception processing is handled. In this detailed post, we will provide code snippets, links to original references, and exploitation details to help you understand the issue and mitigate it effectively.

Background

Before diving into the details of the vulnerability, let's get a quick understanding of the main components involved:

1. Bouncy Castle: Bouncy Castle is a popular open-source cryptography library that provides APIs for Java and C#. It is widely used in various applications to provide encryption, decryption, and other cryptographic functionalities.

2. Java TLS API: The Java TLS API is a part of the Bouncy Castle library, and it provides the implementations of the TLS/SSL protocol for secure communication over a network.

3. JSSE Provider: The Java Secure Socket Extension (JSSE) is a Java-based implementation of SSL and TLS protocols, and it is often used with Bouncy Castle as an additional security provider.

Vulnerability Details

In RSA-based handshakes, when an exception is raised during processing, the time taken to handle that exception can lead to timing-based leakage. An attacker, who is carefully monitoring the timing, can potentially gain insights about the internal state of the server and exploit this information to perform further targeted attacks.

The exploitation of this vulnerability relies on the ability to record subtle differences in the time taken for specific error conditions during the RSA-based handshake process.

Affected Versions

Bouncy Castle Java TLS API and JSSE Provider versions before 1.78 are affected by this vulnerability. It is highly recommended to update to a newer version to mitigate any possible risks associated with this vulnerability.

Code Snippet Demonstrating the Issue

To help you understand the issue better, let's take a look at a code snippet that demonstrates the problem in the exception handling process.

// Perform RSA-based handshake
try {
    performRsaBasedHandshake();
} catch (Exception e) {
    long startTime = System.nanoTime();

    // The vulnerable exception handling process 
    if (e instanceof SpecificError) {
        handleSpecificError(e);
    } else {
        handleGenericError(e);
    }

    long endTime = System.nanoTime();
    long timeTaken = endTime - startTime;

    // The attacker can potentially observe a difference
    // in timeTaken based on the type of exception.
}

In this example, if an attacker can measure the subtle difference in time taken for handling specific errors, they might gain useful information about the server's internal state.

Mitigation Recommendations

To address this vulnerability, Bouncy Castle has released an updated version, 1.78, that incorporates timing-based leakage protection. Affected users are advised to update their Bouncy Castle Java TLS API and JSSE Provider implementations accordingly.

You can download the latest version of Bouncy Castle from their official website at https://www.bouncycastle.org/latest_releases.html.

Conclusion

CVE-2024-30171 is a critical security vulnerability affecting Bouncy Castle Java TLS API and JSSE Provider before version 1.78. The timing-based leakage vulnerability could lead to information disclosure and other potential attacks if not addressed. It is strongly recommended for affected users to update their software to the latest version to mitigate the risk associated with this vulnerability.

Original References

- Bouncy Castle official website: https://www.bouncycastle.org/
- NVD CVE-2024-30171: https://nvd.nist.gov/vuln/detail/CVE-2024-30171
- Bouncy Castle latest releases: https://www.bouncycastle.org/latest_releases.html

Timeline

Published on: 05/14/2024 15:21:52 UTC
Last modified on: 08/19/2024 18:35:08 UTC