The security world is always on high alert for browser vulnerabilities, and CVE-2023-4073 marks another critical point where user safety came under threat on Google Chrome. This article will walk you through what this vulnerability means, how it could be exploited, and share real code snippets to illustrate the risk. All explanations are kept simple for readers new to browser security, but with enough technical detail for those who want to dig deeper.

What is CVE-2023-4073?

CVE-2023-4073 is a high severity security vulnerability affecting Google Chrome on Mac systems, specifically versions before 115..579.170. The issue lies in ANGLE (Almost Native Graphics Layer Engine), a graphics engine used by Chrome to translate WebGL calls to native graphics APIs.

Why Does Out-of-Bounds Matter?

When a program tries to read or write data outside the bounds of allocated memory (an "out-of-bounds" error), it can accidentally overwrite important data or program code. In the context of Chrome, this can mean:

How Could This Be Exploited?

A remote attacker could craft a malicious HTML page that triggers the issue, allowing them to corrupt the heap memory in Chrome's process. The attacker doesn’t need any special privileges—they just need to get a victim to visit a web page.

The specific steps would likely look like this

1. Create a malicious HTML/JavaScript page using WebGL to send crafted data to the ANGLE engine.

Trigger an out-of-bounds write in ANGLE, corrupting heap memory.

3. Potentially use heap corruption as a step toward running arbitrary code or bypassing browser security.

Example Exploit Snippet (Proof-of-Concept)

Let’s look at a code snippet similar to what a security researcher might build for a proof-of-concept (PoC). Note that the exact details of the exploit are not public, but the following demonstrates how WebGL can sometimes be abused for these vulnerabilities:

<!-- Malicious HTML snippet -->
<!DOCTYPE html>
<html>
<body>
<script>
function triggerVuln() {
  // Create a large buffer to manipulate ANGLE's memory handling
  const gl = document.createElement('canvas').getContext('webgl');
  if (!gl) {
    alert('WebGL not supported');
    return;
  }
  
  // Create a suspiciously large array buffer as input
  let bigBuffer = new Float32Array(1e7);

  // Trigger out-of-bounds access by exploiting faulty bounds checks (hypothetical)
  gl.bufferData(gl.ARRAY_BUFFER, bigBuffer, gl.STATIC_DRAW);

  // Continue manipulating state to cause a heap corruption
  for (let i = ; i < 100; i++) {
    gl.bufferSubData(gl.ARRAY_BUFFER, i * 4096, new Float32Array(1024));
  }
}

triggerVuln();
</script>
</body>
</html>

Disclaimer: This is a hypothetical demo and will not exploit the vulnerability.

References & Further Reading

- Google Chrome Release Notes - 115..579.170 for Mac
- CVE-2023-4073 on NIST National Vulnerability Database
- ANGLE GitHub project
- WebGL Security Considerations: MDN Docs

How to Stay Safe

1. Always update your browser. Chrome generally updates automatically, but manual updates are available via chrome://settings/help.

Final Thoughts

CVE-2023-4073 is a reminder that even the most-used browsers can have critical, hidden flaws. With graphics engines like ANGLE being so complex, vulnerabilities can appear and be hard to spot at first glance.

If you’re a developer, keep up with security advisories. If you’re an everyday Chrome user: don’t ignore those update prompts—they’re your frontline defense.

Timeline

Published on: 08/03/2023 01:15:00 UTC
Last modified on: 08/15/2023 16:03:00 UTC