In late 2022, security researchers uncovered a medium-severity bug impacting Google Chrome’s extension system, tracked as CVE-2022-3657. This use-after-free vulnerability opened the door for attackers to exploit users who installed malicious Chrome extensions, potentially leading to harmful heap corruption. If you’re a Chrome user, extension developer, or just interested in browser security, understanding this flaw can help protect your browser from future threats.
What is CVE-2022-3657?
CVE-2022-3657 is a "use-after-free" issue in Google Chrome’s Extensions component. In simple terms, a use-after-free bug happens when an area of computer memory (the "heap") is freed (released by the program), but then the program later tries to access or use it again. That can allow an attacker to insert malicious code into that memory spot, letting them control what the program does next.
This specific vulnerability affected Chrome versions *before* 107..5304.62. An attacker could trick a user into installing a malicious extension, and that extension could trigger the bug to manipulate Chrome's memory and do things it shouldn’t.
How Does This Exploit Work?
Normally, Chrome extensions run in a controlled environment, but due to a programming error, an extension could cause Chrome to "use" memory it had already "freed" (released for re-use elsewhere). By carefully crafting the extension, an attacker can influence what data gets placed where in memory, sometimes causing Chrome to perform actions or access data that it shouldn’t.
Example Scenario
Imagine a Chrome extension that uses JavaScript to interact with the browser’s internal API. After processing some requests, Chrome releases certain memory objects. But, because of this bug, if the extension quickly sends a specially-crafted request, Chrome might end up using one of those objects that it already freed.
By controlling the timing and contents of API calls, a malicious extension could potentially control the freed object's contents—injecting malicious payloads or corrupting important browser data.
Example Code Snippet
Below is a *representative* code snippet that illustrates how an attacker might abuse this vulnerability. (Note: This is a demonstration only and not a fully working exploit.)
// JavaScript code that might be part of a malicious extension
chrome.runtime.onMessage.addListener(function(message, sender, sendResponse) {
// Trigger an API that allocates and then frees memory
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
// Request handled here, but something causes Chrome to free related memory
// QUICKLY send another request that relies on the freed object
setTimeout(function() {
// This second call happens BEFORE Chrome properly cleans up
chrome.tabs.executeScript(tabs[].id, {
code: "console.log('Injected after use-after-free');"
});
}, );
});
});
*This code tries to take advantage of fast, consecutive API calls to manipulate timing issues in memory management.*
Exploit Details
- Practical Exploit: For a real attack, the malicious extension would be engineered to rapidly fire sequences of API calls, racing the Chrome internals to hit use-after-free timings.
- Payload: The attacker can try to inject code or leak data by controlling what gets written to or read from freed memory.
- Success Requirements: The victim would *have* to manually install the attacker's extension (possibly after being tricked by phishing or social engineering).
How Was It Fixed?
The Chrome team released a fix quickly, patching the vulnerability in version 107..5304.62. The patch ensures that once memory is freed, it is not referenced again by extension-provided input, destroying the main attack vector.
Official Chromium security advisory:
CVE Info:
Google Chrome Releases Blog:
Chrome Stable Channel Update for Desktop
How Use-After-Free Exploits Work:
Project Zero: Exploiting Use-After-Free *(general info)*
Update Chrome – Always run the latest version of your browser.
2. Be cautious with extensions – Only install extensions from official sources or reputable developers.
Regularly review installed extensions – Remove anything you don’t use or recognize.
4. Report suspicious activity – If you spot weird browser behavior after installing a new extension, report it to Google.
Conclusion
CVE-2022-3657 is a reminder that even simple programming errors—like referencing memory that’s already been freed—can have big consequences in complex software like browsers. Hackers are always hunting for these flaws to sneak past security fences. By staying informed and careful with what you install, you can help protect yourself from similar exploits in the future.
Timeline
Published on: 11/01/2022 23:15:00 UTC
Last modified on: 12/09/2022 15:06:00 UTC