The Common Vulnerabilities and Exposures (CVE) database has recently reported a high risk flaw in the security systems of popular web browsers, Firefox, Firefox ESR, and the email client Thunderbird. Identified as CVE-2023-34414, this vulnerability exploits a weakness in the activation delay mechanism and allows attackers to bypass invalid TLS certificate checks. This article will discuss the technical details, impact, and possible countermeasures for this vulnerability.

Vulnerability Details

The affected component in these applications is the error page for websites with invalid or improperly configured TLS certificates. Firefox and Thunderbird utilize an activation-delay mechanism to protect prompts and permission dialogs from attacks that exploit human response time delays. However, this delay mechanism is missing in the error page for sites with invalid TLS certificates.

Exploit

To exploit the weakness, an attacker could design a malicious webpage that tries to elicit user clicks at precise locations just before navigating to a site with a certificate error. The attacker simultaneously loads heavy content or scripts on the malicious page to make the renderer extremely busy at that time. Consequently, this creates a gap between the certificate error page's loading and the display's actual refresh.

With the right timing, the elicited clicks might land in that gap and activate the button that overrides the certificate error for that site. This allows the attacker to trick the user into connecting to an insecure site or perform a man-in-the-middle (MITM) attack.

Mitigation

To safeguard against this vulnerability, it is crucial to keep your software up to date. Users should upgrade their Firefox, Firefox ESR, or Thunderbird to the latest version as soon as possible.

In the meantime, you can mitigate this vulnerability by avoiding clicking on untrusted links or websites that might elicit user clicks. Report any suspicious websites to your security team for further analysis.

Conclusion

CVE-2023-34414 is a critical vulnerability that affects the widely used web browsers Firefox, Firefox ESR, and the email client Thunderbird. Attackers can exploit this gap in the activation delay mechanism to bypass the invalid TLS certificate error page, potentially leading to security breaches or MITM attacks. Users and organizations must act promptly to update their software and implement necessary precautions to minimize the possibility of being exploited by this vulnerability.

References

1. CVE-2023-34414 Original Reference
2. Firefox Security Advisory
3. Thunderbird Security Advisory

Timeline

Published on: 06/19/2023 11:15:00 UTC
Last modified on: 06/27/2023 17:02:00 UTC