CVE-2022-3305 - How Use-After-Free in Google ChromeOS’s Survey Function Exposed Millions

Google Chrome is one of the world’s most popular browsers, powering not just desktop and mobile devices, but also serving as the backbone of ChromeOS. In late 2022, security researchers uncovered a serious vulnerability — CVE-2022-3305 — that gave attackers a dangerous opening. Let’s break down what happened, how the attack worked, and what it teaches us about browser security.

What Is CVE-2022-3305?

CVE-2022-3305 is a “use-after-free” bug found in the “survey” component of Chrome when running on ChromeOS, before version 106..5249.62. This type of bug happens when a program continues to use memory (think: a piece of digital paper) even after it’s been “freed” or deleted. Attackers can use this to corrupt the heap (a chunk of memory used by running programs), sometimes letting them run malicious code.

Severity: High
Impacted: Google Chrome on ChromeOS (before 106..5249.62)
Impact: Allows remote attackers to potentially exploit heap corruption, just by tricking a user into visiting a booby-trapped web page.

Official advisory:
- Google Chrome Stable Channel Update for Desktop - September 27, 2022
- NIST NVD Entry

Understanding Use-After-Free: A Simple Example

Imagine an application where you fill out a survey online.

Chrome sets up the memory space for the survey (the “object”).

3. If the user navigates away or quickly closes the survey, Chrome “frees” or deletes the memory space.
4. But, if some code (maybe JavaScript on that page) tries to touch the survey after it’s deleted, it’s using freed memory — that’s a “use-after-free” error.

If attackers can control what’s in the freed spot, they might trick Chrome into running their code instead. Here’s a tiny, simplified illustration:

let surveyWidget = createSurvey();

// User navigates away...
free(surveyWidget);

// Attacker’s code runs, tries to use the surveyWidget again
surveyWidget.collectAnswers(); // Use-after-free!

Of course, Chrome’s code is thousands of lines longer, in C++, but this is the heart of the bug.

Creates a survey in Chrome (via the survey UI component).

2. Forces the browser to free (delete) the survey’s memory, usually by exploiting navigation, timers, or event handlers.
3. Quickly forces an operation on that now-freed memory, usually by triggering another survey function.

If the timing is just right, and if the attacker controls what gets loaded into that part of memory, they could cause Chrome to crash or — in the worst case — run their own code.

Proof-of-Concept: How an Attack Might Look

Note: This code is for educational purposes only.

<!-- survey-attack.html -->
<html>
<body>
<script>
let triggerUAF = async () => {
  // Step 1: Create Survey
  let survey = document.createElement('survey-element');
  document.body.appendChild(survey);

  // Step 2: Schedule survey deletion
  setTimeout(() => {
    document.body.removeChild(survey); // Free the object
  }, 100);

  // Step 3: Use-after-free - Reuse the freed object
  setTimeout(() => {
    try {
      survey.startSurvey(); // Access after free!
    } catch(e) {
      console.log('Survey access failed:', e);
    }
  }, 200);
};
triggerUAF();
</script>
</body>
</html>

*Real-world attacks likely use much more complex code and timing to “spray” the heap and take full control.*

The Impact: Heap Corruption and Potential RCE

“Heap corruption” sounds technical — but it’s a big deal. If an attacker can mess with how memory is managed, they might:

Use “advanced heap spraying” to run malicious code, like spyware, banking trojans, or ransomware

All it takes is for a ChromeOS user to visit a specially crafted malicious web page.

Google’s Fix: Upgrade ASAP

Google fixed this bug in ChromeOS version 106..5249.62. The fix involved patching the survey component to make sure it can’t be used after it’s been freed — usually by using “smart pointers” in C++ that automatically clean up and set references to nullptr.

If you run ChromeOS (or managed it for a school or company):
Make sure all devices are running the latest ChromeOS build, and always apply security updates quickly.

Lessons Learned

- Browsers are a huge attack target. Even little-used UI components like “surveys” can open big doors for hackers.

Keep devices updated. Every Chrome and ChromeOS release includes critical security fixes.

- Memory safety matters. Modern browsers are slowly being rewritten in memory-safe languages like Rust and Go.

Stay vigilant, keep updated, and know that even the best software companies get tripped up by use-after-free bugs like CVE-2022-3305.

Timeline

Published on: 11/01/2022 20:15:00 UTC
Last modified on: 12/09/2022 15:47:00 UTC