Google Chrome is one of the world's most popular web browsers, thanks to its clean interface, speed, and seamless integration with a wide array of platforms and devices. However, like any other software, Chrome has its fair share of security vulnerabilities.

One recently discovered vulnerability, tracked under the identifier CVE-2024-3176, affects the SwiftShader component of Google Chrome before version 117..5938.62. SwiftShader is a software renderer that provides a graphics (GPU) fallback to WebGL when hardware acceleration is not available. This vulnerability allows a remote attacker to perform an out-of-bounds memory write using a malicious HTML page. In this blog post, we will explore CVE-2024-3176 and discuss its impact, the proof of concept, and references to original research.

Exploit Details

CVE-2024-3176 is classified as an 'Out of Bounds Write' vulnerability due to the incorrect handling of array indices in the SwiftShader component. When exploited, this vulnerability allows an attacker to corrupt adjacent memory regions, which could potentially lead to the execution of arbitrary code within the context of the affected application.

The Chromium project has designated this vulnerability its security severity as 'High,' which means that it demands immediate attention and merits a swift resolution.

As an example, consider the following code snippet

// SwiftShader/src/Reactor/Intermediate.cpp

// ... code ...

Value *Nucleus::createMaskedLoad(Value *ptr, int alignment, Value *mask)
{
  // ... code ...

  Value *maskComponents[4];
  Type *maskType = mask->getType();

  for (unsigned int i = ; i < maskType->getVectorSize(); i++)
  {
    maskComponents[i] = createExtractElement(mask, i);
  }

  // ... code ...
}

In the code above, the createMaskedLoad function incorrectly handles the indices when iterating over the elements in maskType->getVectorSize(). This can lead to out-of-bounds memory writes if the vector size is larger than four, causing potential corruption and exploitation by an attacker.

Proof of Concept

A proof-of-concept (PoC) for exploiting this vulnerability would involve crafting a malicious HTML page containing WebGL content designed specifically to trigger this out-of-bounds behavior in SwiftShader. An example of a WebGL shader that could be used to exploit this vulnerability might look like this:

<!-- index.html -->

<!DOCTYPE html>
<html>
<head>
  <title>CVE-2024-3176 PoC</title>
</head>
<body>
  <canvas id="glCanvas"></canvas>
  <script src="exploit.js"></script>
</body>
</html>

// exploit.js

// ... code to set up WebGL context ...

// Define the malicious shader
const maliciousShaderSource = `
  uniform int vecSize;
  void main() {
    float vecArray[128];
    for (int i = ; i < vecSize; i++) {
      vecArray[i] = float(i);
    }
    // ... code to trigger the vulnerability ...
  }
`;

// ... code to compile and use the malicious shader ...

By visiting the malicious web page, a user running a vulnerable version of Google Chrome may be exposed to the exploitation of CVE-2024-3176. This could potentially allow arbitrary code execution within the context of the web browser, leading to various nefarious outcomes.

Original References

The Google Chrome team has promptly addressed this vulnerability by releasing an updated version of the browser. For more information on the details of this vulnerability and related discussions, consult the following resources:

- Chromium Bug Tracker for CVE-2024-3176
- Google Chrome Release Blog Post (117..5938.62)

Conclusion

CVE-2024-3176 is a security vulnerability in the SwiftShader component of Google Chrome, allowing an attacker to perform an out-of-bounds memory write via a malicious HTML page. Users are strongly encouraged to update their Chrome installations to the latest version (117..5938.62 or later) to mitigate this vulnerability. As always, practicing vigilance when browsing unfamiliar websites and keeping software up-to-date can prevent security issues from affecting your system.

Timeline

Published on: 07/16/2024 23:15:24 UTC
Last modified on: 07/18/2024 14:47:38 UTC