CVE-2021-3336 Explained : Impact and Mitigation

DoTls13CertificateVerify in tls13.c in wolfSSL before 4.7.0 does not cease processing for certain anomalous peer behavior like sending an ED22519, ED448, ECC, or RSA signature without the corresponding certificate. This affects the client side by allowing man-in-the-middle attackers to impersonate TLS 1.3 servers.

Understanding CVE-2021-3336

In this section, we will delve into the details of CVE-2021-3336, a vulnerability found in wolfSSL.

What is CVE-2021-3336?

CVE-2021-3336 is a vulnerability in wolfSSL before version 4.7.0 that arises due to a flaw in DoTls13CertificateVerify in tls13.c. It fails to stop processing in the presence of certain unusual peer behavior. This flaw opens up the client side to man-in-the-middle attacks where attackers can pose as TLS 1.3 servers.

The Impact of CVE-2021-3336

The impact of CVE-2021-3336 is significant as it compromises the integrity and security of TLS 1.3 communication by allowing attackers to impersonate servers. This can lead to unauthorized access and data interception compromising confidentiality.

Technical Details of CVE-2021-3336

Let's explore the technical aspects of the CVE-2021-3336 vulnerability in wolfSSL.

Vulnerability Description

The vulnerability lies in the improper handling of anomalous peer behavior, such as sending specific signatures without the required certificate, in DoTls13CertificateVerify of tls13.c in wolfSSL before version 4.7.0.

Affected Systems and Versions

All versions of wolfSSL before 4.7.0 are affected by this vulnerability. Users are advised to update to a secure version to mitigate the risk.

Exploitation Mechanism

The vulnerability can be exploited by malicious actors who can intercept the communication between a client and a server by impersonating the server due to the incomplete processing of anomalous peer behavior.

Mitigation and Prevention

Learn how to protect your systems from CVE-2021-3336 and prevent potential exploitation.

Immediate Steps to Take

Update wolfSSL to version 4.7.0 or later to address the vulnerability and ensure secure communication.
Monitor network traffic for any suspicious activity that may indicate exploitation of this vulnerability.

Long-Term Security Practices

Implement mutual authentication between clients and servers to prevent man-in-the-middle attacks.
Regularly review and update TLS protocols and configurations to maintain a secure communication environment.

Patching and Updates

Stay informed about security updates and patches released by wolfSSL to address vulnerabilities and enhance the security of your systems.