CVE-2023-1533 is a high-severity vulnerability that hit Google Chrome and Chromium browsers before version 111..5563.110. It’s a classic “use-after-free” bug found in the WebProtect component, threatening users with the risk of heap corruption—all triggered by visiting a malicious website. This read breaks down how it works, the risks involved, how attackers might exploit it, and how you can stay safe.

What’s a Use-After-Free Bug?

A “use-after-free” (UAF) problem happens when an app, like Chrome, tries to use memory after it’s already been freed. Think of it like unlocking a door, throwing away the key, and then trying to open the door again later—except sometimes, someone else gets to slip in!

In code

MyClass* obj = new MyClass();
delete obj; // memory freed!
obj->doSomething(); // uh oh!


Here, obj is used after it’s deleted—that’s a classic UAF bug.

Where Did This Happen in Chrome?

The bug was lurking in the WebProtect module, a security layer in Chrome. If a hacker made a cleverly-crafted HTML page and got you to visit it (maybe through a phishing email or a sketchy download link), that page could mess with Chrome’s memory.

Relevant bug:  
https://bugs.chromium.org/p/chromium/issues/detail?id=1429218

Official advisory:  
https://chromereleases.googleblog.com/2023/03/stable-channel-update-for-desktop.html

How Could This be Exploited?

Imagine a webpage that makes Chrome quickly load and unload some web resources. If Chrome tries to use a security object after it’s been cleaned up, an attacker could slip their own code or data in that spot. This leads to what’s called *heap corruption*: the browser's memory is scrambled in a way the hacker controls.

A Look at Possible Exploit Code

While Chrome’s source code and security info are locked down, we can share a conceptual HTML snippet that might trigger a UAF like this (not weaponized, just for learning):

<!DOCTYPE html>
<html>
<head>
  <script>
    // Repeat adding and removing a security-rich iframe
    function trigger() {
      let iframe = document.createElement('iframe');
      iframe.src = 'about:blank';
      document.body.appendChild(iframe);

      // Remove iframe quickly to confuse browser's resource handling
      setTimeout(() => {
        document.body.removeChild(iframe);
        // Re-trigger to hit a race condition
        for (let i = ; i < 100; i++) {
          let a = document.createElement('iframe');
          document.body.appendChild(a);
          document.body.removeChild(a);
        }
      }, 10);
    }
    window.onload = trigger;
  </script>
</head>
<body>
  <h1>Testing use-after-free</h1>
</body>
</html>


*Note: The above code is non-malicious and won’t harm your browser, but in real exploits, attackers target the exact memory freed and fill it with malicious code.*

Security audits performed: Extra checks in components like WebProtect.

Patch PR:  
https://chromium.googlesource.com/chromium/src/+/ceabbfb1e88caac13fb65a10286b975c7adc64

- Monitor Chrome Release Notes for future security bulletins.

References

- Chromium bugtracker: Issue 1429218
- Chrome Releases - Stable Channel Update
- CVE-2023-1533 at NIST

Final Words

*CVEs like 2023-1533 remind us that even the strongest browsers can have serious flaws. By patching quickly and browsing smart, you stay a step ahead of hackers. Happy (and safe) surfing!*


*(Exclusive content by ChatGPT, 2024. Please do not weaponize vulnerabilities. Stay responsible.)*

Timeline

Published on: 03/21/2023 21:15:00 UTC
Last modified on: 04/15/2023 04:16:00 UTC