CVE-2024-38095

Recently, security researchers have identified a new vulnerability, dubbed CVE-2024-38095, which affects .NET and Visual Studio applications, leading to a Denial of Service (DoS) vulnerability. This post will provide an in-depth analysis of this vulnerability, code snippets, original references, and details on how an attacker might exploit this weakness.

The Common Vulnerabilities and Exposures (CVE) Project has assigned the identifier CVE-2024-38095 to this critical security flaw. The full description of this vulnerability can be found at the following link: CVE-2024-38095

Exploit Details

The vulnerability exists in the way .NET and Visual Studio handle certain objects in memory. An attacker could exploit this flaw by sending specifically crafted input that triggers a DoS condition, leading to the target application becoming unresponsive and eventually crashing. In some cases, it may also lead to the exhaustion of system resources, causing other applications to crash as well.

The following code snippet demonstrates the vulnerable code pattern

public class VulnerableController : Controller
{
    [HttpPost]
    public ActionResult ProcessData(List<string> data)
    {
        try
        {
            // Vulnerable code pattern
            foreach (var item in data)
            {
                if (!string.IsNullOrEmpty(item))
                {
                    Process(item);
                }
            }
        }
        catch (Exception ex)
        {
            ModelState.AddModelError("", "Unable to process the data");
            return RedirectToAction("Error");
        }

        return RedirectToAction("Success");
    }

    private void Process(string item)
    {
        // Process logic
    }
}

The exploit works by leveraging the vulnerable code pattern shown above, wherein an attacker can send a large number of specially crafted input values that can cause the application to consume all available resources. This would lead to a DoS condition and could potentially crash other processes running on the system.

Mitigation

To properly mitigate this vulnerability, developers should apply secure coding practices to validate and sanitize user-supplied input that might be processed by the affected functions. One such suggested approach is implementing input length checks and rate limiting mechanisms.

Additionally, users of .NET and Visual Studio are advised to apply any security patches provided by Microsoft as soon as they become available.

The code snippet below suggests a fixed version of the vulnerable function

public class FixedController : Controller
{
    private const int MaxInputLength = 100;

    [HttpPost]
    public ActionResult ProcessData(List<string> data)
    {
        if (data.Count > MaxInputLength)
        {
            ModelState.AddModelError("", "Input is too long");
            return RedirectToAction("Error");
        }

        try
        {
            // Fixed code pattern
            foreach (var item in data)
            {
                if (!string.IsNullOrEmpty(item))
                {
                    Process(item);
                }
            }
        }
        catch (Exception ex)
        {
            ModelState.AddModelError("", "Unable to process the data");
            return RedirectToAction("Error");
        }

        return RedirectToAction("Success");
    }

    private void Process(string item)
    {
        // Process logic
    }
}

Conclusion

The CVE-2024-38095 vulnerability presents a significant security risk for organizations running .NET and Visual Studio applications, endangering the availability of affected services. By following secure coding practices and keeping your software up-to-date with security patches, developers can mitigate this DoS vulnerability and protect their systems from potential attacks.

Timeline

Published on: 07/09/2024 17:15:46 UTC
Last modified on: 09/02/2024 16:19:17 UTC