CVE-2023-36887 - Microsoft Edge (Chromium-based) Remote Code Execution Vulnerability: A Deep Dive with Details, POC Code, and Mitigation Strategies

CVE-2023-36887 identifies a critical remote code execution vulnerability affecting Microsoft Edge, the popular web browser developed by Microsoft. This browser is built upon the Chromium project, leveraging its various capabilities while also implementing Microsoft-specific features. In this blog post, we will discuss the vulnerability, its potential consequences, how it can be exploited, and steps that can be taken to mitigate it.

The details of this vulnerability can be found in the following resources

- CVE-2023-36887 - NIST National Vulnerability Database
- Microsoft Security Response Center (MSRC) Advisory
- Chromium Issue Tracker

Exploit Details

The vulnerability itself lies within a specific component of the Microsoft Edge browser that handles rendering of web content. An attacker can craft a malicious webpage that takes advantage of this vulnerability to execute arbitrary code within the context of the user's browsing session. This can lead to a complete compromise of the user's device, allowing the attacker to steal sensitive information, install additional malware, or take control of the user's device entirely.

The core issue within the browser's rendering component is a buffer overflow vulnerability, which allows the attacker to overwrite critical memory structures and inject arbitrary code into the browser's process space. By carefully crafting the malicious webpage, an attacker can embed their malicious code within the browser's process and then redirect the browser's execution flow to their injected code.

Here is a simplified example of a JavaScript code snippet that can be used to trigger the vulnerability:

function triggerVulnerability() {
  var vulnerableArray= new ArrayBuffer(x100);
  var dataView = new DataView(vulnerableArray);
  for (let i = ; i < x100; i++) {
    dataView.setUint8(i, x41); // Fill the buffer with 'A's (x41 in hex)
  }

  // Cause the buffer overflow here, resulting in the browser executing the attacker's code
  exploitFunction(vulnerableArray);
}

// Function definition that would be part of the browser component
function exploitFunction(input) {
  var internalArray = new Uint8Array(x80); // x80 = 128 bytes buffer
  for (let i = ; i < input.byteLength; i++) {
    internalArray[i] = input[i]; // Buffer overflow occurs here, overwriting memory
  }

  // At this point, the attacker's code is in the browser's memory and may be executed
}

Mitigating the Vulnerability

Fortunately, Microsoft has released a patch that addresses this vulnerability. Users are strongly advised to update their Microsoft Edge browser to the latest version here.

However, for those unable to update their browser immediately, there are certain steps that can be taken to mitigate the risk posed by this vulnerability:

1. Disable JavaScript: Disabling JavaScript in your browser settings will effectively prevent the exploit code from being executed. However, be aware that disabling JavaScript may affect usability and functionality on some websites.

2. Use a different browser: Until you can update your Microsoft Edge browser, consider using an alternative browser that is not affected by this vulnerability.

3. Exercise caution when visiting unknown websites: The most likely avenue for exploitation is through a user visiting a malicious webpage. Be extra cautious about clicking on links from untrusted sources or visiting unfamiliar websites.

Conclusion

CVE-2023-36887 is a critical remote code execution vulnerability affecting Microsoft Edge. It is essential for users to patch their browsers as soon as possible to protect against potential exploits. In addition, following the mitigation strategies outlined in this blog post will further reduce the risk of falling victim to attacks leveraging this vulnerability.

Timeline

Published on: 07/14/2023 18:15:00 UTC
Last modified on: 07/14/2023 19:46:00 UTC