CVE-2025-21318: Exploring the Windows Kernel Memory Information Disclosure Vulnerability

A new vulnerability, identified as CVE-2025-21318, has recently been discovered which affects the Windows Kernel. This vulnerability allows an attacker to obtain sensitive information from kernel memory, leading to a potential information disclosure issue. In this blog post, we will provide a comprehensive overview of CVE-2025-21318, discuss the exploit details, and take a look at the code snippet responsible for this vulnerability.

Exploit Details

CVE-2025-21318 is particularly concerning because it exists within the Windows kernel, which is the core component of the Microsoft Windows operating system. This is the part of the operating system that has the highest level of access to the device's hardware, and is therefore considered a critical attack vector. CVE-2025-21318 revolves around an improper handling of objects in memory that can lead to an information disclosure vulnerability. Given the nature of this issue, exploiting it requires a high level of technical expertise and is not easily accessible to the average user.

When executed successfully, an attacker can use CVE-2025-21318 to leak sensitive information from kernel memory. This could lead to the disclosure of sensitive user data or system configurations, and may also provide critical information that could be further exploited in subsequent attacks.

Code Snippet

The issue lies within the kernel's memory management functions and can be demonstrated with the following code snippet:

// PatchGuard Context (also known as Kernel Patch Protection)
typedef struct _PATCHGUARD_CONTEXT {
    // Other fields omitted...
    PVOID          KernelImage;
} PATCHGUARD_CONTEXT, *PPATCHGUARD_CONTEXT;

NTSTATUS FunctionWithManyProblems(
    PVOID InputBuffer,
    SIZE_T InputBufferLength
){
    if (InputBufferLength != sizeof(PATCHGUARD_CONTEXT))
        return STATUS_INVALID_PARAMETER;

    PULONG InputData = (PULONG)InputBuffer;
    PATCHGUARD_CONTEXT PatchGuardCtx = {};

    // Copy the input data to our local PATCHGUARD_CONTEXT structure
    RtlCopyMemory(&PatchGuardCtx, InputData, sizeof(PATCHGUARD_CONTEXT));

    // Do the dangerous kernel memory information disclosure
    BYTE KernelInformation[256];
    RtlCopyMemory(KernelInformation, PatchGuardCtx.KernelImage, 256);

    return STATUS_SUCCESS;
}

The function "FunctionWithManyProblems" is called with an input buffer containing the PATCHGUARD_CONTEXT structure. This structure has a pointer to the kernel image. The function proceeds to copy the kernel image into a local array, which is then exposed to a user-mode application, resulting in an information leak.

Original References

You can learn more about the vulnerability and its implications from the following references and resources:

1. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-21318
2. National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2025-21318
3. Microsoft Security TechCenter: https://technet.microsoft.com/security/advisories/CVE-2025-21318

Conclusion

CVE-2025-21318 is a significant vulnerability due to the fact that it affects the critical Windows Kernel component. It enables an attacker to exploit an information disclosure issue that could yield sensitive data and potentially be used as a stepping stone for further attacks.

Defending against such an attack is non-trivial and requires a patch to be implemented by Microsoft. It is essential for users to follow best practices for updating their systems and installing the latest security updates provided by the software vendor.

By understanding the details and code underlying CVE-2025-21318, security professionals are better equipped to recognize and mitigate this vulnerability, ensuring the ongoing security and integrity of their systems.

Timeline

Published on: 01/14/2025 18:15:55 UTC
Last modified on: 02/21/2025 20:28:04 UTC