CVE-2023-3724 : Exploit Details and Defense Strategies

This CVE-2023-3724 is related to a vulnerability in wolfSSL that affects TLS 1.3 clients when connecting to a malicious server. The issue arises when a TLS 1.3 client does not receive either a PSK (pre shared key) extension or a KSE (key share extension) from the server, leading to the use of a predictable buffer for the IKM (Input Keying Material) value during session master secret key generation. This predictable IKM value compromises the generated key, potentially enabling eavesdroppers to reconstruct it and gain unauthorized access to or manipulate message contents within the session.

Understanding CVE-2023-3724

This vulnerability impacts the security of TLS 1.3 connections initiated by wolfSSL clients, emphasizing the importance of updating the wolfSSL version to mitigate the risk effectively.

What is CVE-2023-3724?

The vulnerability allows for the compromise of session encryption keys in TLS 1.3 connections due to the use of a predictable buffer for the IKM value in the absence of necessary extensions from a malicious server, potentially leading to unauthorized access or manipulation of communication contents.

The Impact of CVE-2023-3724

The vulnerability poses a critical threat to the confidentiality, integrity, and availability of data exchanged over insecure TLS 1.3 sessions, highlighting the importance of prompt mitigation to prevent unauthorized access and data manipulation.

Technical Details of CVE-2023-3724

The vulnerability is categorized under CWE-20 (Improper Input Validation) and has a CVSSv3.1 base severity score of 9.1 (Critical) with high impacts on confidentiality, integrity, and availability.

Vulnerability Description

When TLS 1.3 clients do not receive essential extensions from a malicious server, a predictable buffer is used for generating session master secret keys, potentially compromising the security and confidentiality of communication.

Affected Systems and Versions

wolfSSL versions up to and including 5.6.0 are impacted by this vulnerability, specifically affecting TLS 1.3 client implementations utilizing the 3.14.0 release bundle.

Exploitation Mechanism

The exploitation of this vulnerability requires an attacker to intercept and manipulate communication between a TLS 1.3 client and a malicious server that does not provide the necessary extensions, enabling unauthorized access and potential data manipulation.

Mitigation and Prevention

To address CVE-2023-3724 and enhance the security of TLS 1.3 connections, immediate steps and long-term security practices should be implemented alongside applying relevant patches and updates.

Immediate Steps to Take

TLS 1.3 client users are advised to update their wolfSSL version to mitigate the vulnerability effectively, reducing the risk of unauthorized access and data manipulation during secure sessions.

Long-Term Security Practices

Employing secure communication protocols, implementing robust encryption mechanisms, and regularly updating cryptographic libraries are essential long-term strategies to fortify the security of TLS connections and prevent exploitation of vulnerabilities like CVE-2023-3724.

Patching and Updates

wolfSSL has released a patch to address the vulnerability, available through the GitHub pull request numbered 6412. Users are recommended to apply this patch promptly to secure their TLS 1.3 client implementations and prevent potential security breaches.

This detailed insight into CVE-2023-3724 underscores the criticality of securing TLS 1.3 connections and the necessity of proactive measures to mitigate vulnerabilities effectively.