CVE CyberSecurity Database News

CVE-2022-26382: Critical Firefox Vulnerability - Exploiting Side-Channel Attacks on Autofill Text Rendering with Custom Fonts

Poster -

In February of 2022, a critical vulnerability under the identifier CVE-2022-26382 was discovered in Mozilla Firefox. The issue involves how the browser renders the text displayed in Autofill tooltips. Although this text cannot be directly read by JavaScript, the vulnerability allowed malicious actors to exploit side-channel attacks on the text rendering process by using specially crafted fonts. This vulnerability affects Firefox versions below 98..

The purpose of this long read is to provide an in-depth understanding of the CVE-2022-26382 vulnerability, including the original references, exploit details, and a code snippet of the attack. By the end of this informative guide, you will know what you need to do to protect your browser from potential threats related to this vulnerability.

Original References

The CVE-2022-26382 vulnerability was initially reported by Mozilla Foundation Security Advisory - MFSA2022-07. The advisory mentioned that researchers from Doyensec, a leading software security company, discovered this vulnerability as part of their research.

1. Mozilla Foundation Security Advisory - MFSA2022-07
2. Doyensec's official website - https://doyensec.com

How the Vulnerability Works

Autofill tooltips are a helpful feature in browsers that allow users to fill out web forms more efficiently. When a user starts typing or clicks on a form field, the browser predicts and suggests possible text based on previously entered data. This makes filling out forms faster and more convenient.

However, with the CVE-2022-26382 vulnerability, a malicious website can exploit a side-channel attack on the text rendering process. By using custom-crafted fonts and monitoring the time taken to render Autofill tooltips, an attacker can obtain information about the text content without having direct access to the underlying data.

Let's take a closer look at this exploit in action with a sample code snippet.

Suppose we create a page with the following HTML content

<!DOCTYPE html>
<html>
<head>
  <style>
    /* Custom font crafted to trigger side-channel attack */
    @font-face {
      font-family: 'EvilFont';
      src: url('evil-font.woff');
    }
    
    /* Apply custom font to Autofill tooltip */
    input:-webkit-autofill::first-line {
      font-family: 'EvilFont', sans-serif !important;
    }
  </style>
</head>
<body>
  <form>
    <label for="email">Email:</label>
    <input type="email" id="email" name="email" required>
    <input type="submit" value="Submit">
  </form>
</body>
</html>

In this example, we use a custom-crafted font called "EvilFont" which is designed to exploit the vulnerability. By applying this font to the Autofill tooltip text, attackers can time how long it takes to render the text and infer its content based on these timing measurements.

Exploit Details

The CVE-2022-26382 vulnerability allows for exploitation by carefully analyzing these timing measurements obtained from the rendering process of Autofill tooltips using the custom-crafted font. The attack involves a combination of elements:

Analyzing the timing measurements to extract information about the Autofill text.

This exploit affects Firefox versions below 98., and successfully carrying out this attack can lead to the compromise of sensitive data, including personal information, credentials, and other crucial data stored in the browser's Autofill feature.

Conclusion

In conclusion, the CVE-2022-26382 vulnerability exposed a critical weakness in the way Mozilla Firefox handled text rendering in Autofill tooltips. By exploiting this vulnerability, attackers can potentially gain unauthorized access to sensitive Autofill data.

To protect your browser and ensure the security of your data, it is essential to update your Firefox browser to version 98. or higher. Regularly updating your software is a crucial practice in maintaining good cybersecurity hygiene. Stay safe online by staying informed, and be proactive in keeping your browser and other software up-to-date.

Timeline

Published on: 12/22/2022 20:15:00 UTC
Last modified on: 12/30/2022 15:01:00 UTC