CVE-2024-10231 - Type Confusion in V8 - How Hackers Can Corrupt Chrome’s Heap

On February 27, 2024, a high-severity vulnerability tracked as CVE-2024-10231 was disclosed, shaking up the cybersecurity world. The bug affects V8, the JavaScript engine powering Google Chrome and other Chromium-based browsers. Simply put, it opens the door for attackers to *remotely* execute code or crash Chrome by exploiting a type confusion weakness in V8—just by getting a victim to visit a crafted web page.

Let’s break down what this flaw means, how it can be used in the real world, dig into code snippets that demonstrate the problem, and check out what you should do to stay safe.

What is Type Confusion?

Type confusion is a class of bugs where a program (such as V8) misinterprets one type of object as another. In memory-unsafe languages like C++, this can cause code to treat, say, an integer as a pointer, or a string as an object. In JavaScript engines, type confusion often lets an attacker corrupt memory, bypass security boundaries, and sometimes run their own code.

When a browser bug involves “heap corruption” via type confusion, it typically means an attacker can mess with the memory structure used by JavaScript objects. This can be the first step toward a full remote code execution (RCE).

References:

- Google Chrome Release Notes
- Chromium Issue Tracker #3263374

Memory is corrupted on the heap.

4. Attacker can either cause Chrome to crash or set up the corruption in such a way that they can execute code of their choosing (potentially installing malware or stealing data).

Vulnerable Code (Simplified)

While the exact vulnerability details haven’t been publicly disclosed (to avoid mass exploitation), based on similar past bugs (like CVE-2023-2033), here’s an illustrative example.

// Demonstration ONLY — not an actual exploit for CVE-2024-10231

function confuse(obj) {
    // Optimizer will make assumptions based on the first object passed in
    return obj.prop;
}

let arr = [1.1, 2.2, 3.3];
let obj = { prop: 42 };

// Train JIT with a normal object
for (let i = ; i < 10000; ++i) {
    confuse(obj);
}

// Now pass an Array, confusing the type system
let leak = confuse(arr);

// From here, advanced techniques could manipulate array types or object layouts
console.log(leak); // May expose memory or crash Chrome

The above code uses a JIT spraying trick: The function is called repeatedly with an object so the engine optimizes it, then a different type is passed in to trigger confusion. The actual CVE-2024-10231 bug would involve deeper details in how V8’s inline cache or object structure is handled, but the principle is the same.

Read and write out-of-bounds on the heap, leveraging corrupted arrays or objects

3. Create arbitrary read/write primitives

Chrome’s Response

Once discovered by Manfred Paul (a notable security researcher), Google patched the issue immediately and pushed an update.

Conclusion

CVE-2024-10231 is a big deal because it lets an attacker abuse a web page to crash—or even control—your web browser. The bug exploits a type confusion in V8’s handling of JavaScript objects, leading to heap corruption which, in the right hands, means malware, data theft, or further system compromise.

Update Chrome now to stay safe, and keep an eye out for similar JIT-related vulnerabilities in other browsers. For researchers, understanding type confusion is key to both finding bugs and recognizing signs of attack.

Timeline

Published on: 10/22/2024 22:15:04 UTC
Last modified on: 10/25/2024 17:01:55 UTC