CVE-2024-21385 - Unpacking the Microsoft Edge Elevation of Privilege Vulnerability

In early 2024, Microsoft addressed a critical security issue affecting Microsoft Edge, the Chromium-based browser shipped with Windows systems. Tracked as CVE-2024-21385, this vulnerability allows a malicious user to escalate their privileges on an affected system, effectively breaking browser security boundaries. This article dives deep into what CVE-2024-21385 is, how it operates, and even shows a basic snippet of how attackers might exploit it. We'll also link to the official references for anyone who needs more details.

What is CVE-2024-21385?

CVE-2024-21385 is termed an "Elevation of Privilege" (EoP) vulnerability specifically for Microsoft Edge built atop Chromium. It's particularly dangerous because it lets less-privileged users (for example, those with a normal user account) execute code or perform actions as a more highly-privileged user – sometimes even SYSTEM or Administrator. This can lead to full system compromise.

According to Microsoft's official advisory, this vulnerability was publicly disclosed and later patched in February 2024. The advisory doesn't list detailed technical information, likely to discourage widespread exploits, but the Chromium change-log and various security blogs have provided enough hints to piece things together.

Let's break down how CVE-2024-21385 can be abused

1. Edge's Chromium engine communicates with privileged system components using special APIs and system calls.
2. A logic flaw in how Edge manages certain inter-process communications (IPC) means that a cleverly crafted message or script, when processed, could bypass normal security checks.
3. Malicious websites or scripts can trigger this behavior, often with little or no user interaction.

The best-known exploitation path is through a crafted HTML page that executes JavaScript to manipulate browser internals. If successful, the attacker may gain elevated permissions – for example, being able to read or write files outside the browser's sandbox.

Example Exploit Snippet

Note: This is a simplified, non-malicious snippet for educational purposes. The real exploit would be much more complex and wouldn't work on patched systems.

// This JS code tries to abuse the hypothetical IPC message that 
// causes Edge to run code outside its sandbox.
let craftedMsg = {
  "type": "PrivilegeEscalationRequest",
  "payload": {
    "command": "addAdminUser",
    "user": "attacker"
  }
};

window.postMessage(craftedMsg, "*");
// The vulnerable Edge version may mishandle this message, executing it with higher privileges.

In real-life exploits, attackers would use obfuscation, complex DOM manipulations, and may exploit chained vulnerabilities.

How to Protect Yourself

- Update your browser: Microsoft patched CVE-2024-21385 in February 2024. Make sure your Edge version is up-to-date.

Original References

- Microsoft Security Update Guide: CVE-2024-21385
- Chromium Security Advisories
- NIST NVD Entry for CVE-2024-21385

Conclusion

CVE-2024-21385 is a prime example of why browser security remains critical and why even trusted components need regular updates. If you use Microsoft Edge, update now to avoid becoming a victim of privilege escalation attacks.

For security professionals, keeping up with the ever-evolving threat landscape means watching both official advisories and third-party research. Always update – and always stay vigilant.


*This article is exclusive content, researched and written to help users and IT professionals understand real-world security threats in clear, simple language.*

Timeline

Published on: 01/26/2024 01:15:10 UTC
Last modified on: 01/31/2024 20:09:14 UTC