In September 2022, Google patched a serious vulnerability tracked as CVE-2022-3306. This flaw is found in Google Chrome on ChromeOS versions prior to 106..5249.62. It’s a “use-after-free” bug in Chrome’s Survey component. If exploited, it allows a remote attacker to corrupt the heap and potentially execute code by tricking a user into visiting a malicious web page.

Attack vector: Malicious HTML page.

This vulnerability allows attackers to take advantage of a logic error that occurs when Chrome tries to use already freed memory (a “dangling pointer”). Such attacks can let hackers run arbitrary code, crash your browser, or steal sensitive data.

Use: Code accidentally tries to use the memory again, even though it’s supposed to be gone.

When this happens, clever attackers can fill that spot with their own data (“heap spraying”). If the browser follows a malicious pointer, it can run attacker code.

Vulnerability Details

The bug lives in the way Chrome handles survey objects on web pages. By manipulating the sequence of actions (like removing survey UI elements rapidly, or triggering JavaScript event handlers at the right time), attackers can cause Chrome to access memory that’s already been freed.

Chromium’s security bulletin

> “Use after free in survey in Google Chrome on ChromeOS prior to 106..5249.62 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.”  
> *(Chromium security severity: High)*

You can see the official entry here: CVE-2022-3306 | NVD

Platform: ChromeOS < 106..5249.62

- Bug Tracking: Chromium Issue 1341592

The patch fixes the bug by ensuring that any attempt to access or trigger survey UI checks if the object is still valid, reducing chances of using freed memory.

Example Exploit Code

While a full exploit is complex, here’s a simplified demonstration of how a use-after-free could be triggered in JavaScript:

<!DOCTYPE html>
<html>
  <body>
    <script>
      // Dummy function to simulate a Chrome survey element
      function triggerSurveyUAF() {
        let surveyElem = document.createElement('div');
        surveyElem.id = "survey";
        document.body.appendChild(surveyElem);

        // Simulate some async action that removes the element
        setTimeout(function() {
          document.body.removeChild(surveyElem);
          // Use-after-free happens if Chrome still tries to use 'surveyElem' after this
        }, 100);

        // Attacker repeatedly allocates memory to fill the freed spot
        let spray = [];
        for (let i = ; i < 10000; i++) {
          spray.push(document.createElement('div'));
        }
      }

      // Simulate a page load that triggers the bug
      window.onload = triggerSurveyUAF;
    </script>
  </body>
</html>

Note: This is a synthetic example. The real exploit would require careful heap manipulation and browser-specific exploitation. But it shows the basic idea: remove an object, then heap spray to occupy the freed slot.

References

- CVE-2022-3306 - National Vulnerability Database
- Chromium Issue 1341592 Tracking
- Google Chrome Release Notes
- Chrome Security FAQ


Summary:  
*CVE-2022-3306* is a high-risk ChromeOS bug that could let attackers corrupt memory by tricking Chrome into using freed objects, especially via manipulated survey pages. Always keep your browser and OS up to date to stay protected against such issues. Be wary of suspicious links and web content, as attackers often exploit use-after-free bugs through innocent-looking web pages.

Timeline

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