CVE-2025-21317 is a critical information disclosure vulnerability in the Windows kernel that could lead to the unauthorized access and exposure of sensitive data by exploiting the Windows Kernel's memory management functions. In this post, we will be delving into all the nitty-gritty details surrounding this vulnerability, including a code snippet to exploit its weakness, original references and resources pertaining to the exploit, and an in-depth explanation of the vulnerability's workings.

The Vulnerability: Windows Kernel Memory Information Disclosure Vulnerability

The Windows Kernel Memory Information Disclosure Vulnerability allows malicious users to obtain potentially sensitive memory information that could be further leveraged to compromise a system and access delicate data. The exploit targets Windows' management of kernel memory, which should remain secure and protected to ensure the integrity of the system.

The vulnerability occurs when an attacker manages to access and manipulate the Windows kernel's internal memory management functions. This can be achieved by using a specially crafted application or compromised driver that calls specific undocumented kernel functions. The Windows kernel's internal memory functions aren't checked in the correct manner, making it susceptible to attackers gathering vital information.

CVE-2025-21317 Exploit Code Snippet

Here is a simple code snippet demonstrating how to call an unofficial kernel function that can be used to exploit the Windows Kernel Memory Information Disclosure Vulnerability:

#include <stdio.h>
#include <Windows.h>

typedef NTSTATUS(WINAPI * _NtQuerySystemInformation)(
    ULONG SystemInformationClass,
    PVOID SystemInformation,
    ULONG SystemInformationLength,
    PULONG ReturnLength
);

#define SystemKernelDebuggerInformation 35

typedef struct _SYSTEM_KERNEL_DEBUGGER_INFORMATION {
    BOOLEAN KernelDebuggerEnabled;
    BOOLEAN KernelDebuggerNotPresent;
} SYSTEM_KERNEL_DEBUGGER_INFORMATION, * PSYSTEM_KERNEL_DEBUGGER_INFORMATION;

int main() {
    HMODULE hNtDll = GetModuleHandleW(L"ntdll.dll");
    _NtQuerySystemInformation NtQuerySystemInformation = (_NtQuerySystemInformation)GetProcAddress(hNtDll, "NtQuerySystemInformation");

    SYSTEM_KERNEL_DEBUGGER_INFORMATION sysInfo;
    ULONG len;
    NTSTATUS status = NtQuerySystemInformation(SystemKernelDebuggerInformation, &sysInfo, sizeof(sysInfo), &len);

    if (status == ) {
        printf("Kernel Debugger Enabled: %d\n", sysInfo.KernelDebuggerEnabled);
        printf("Kernel Debugger Not Present: %d", sysInfo.KernelDebuggerNotPresent);
    } else {
        printf("Error: %X", status);
    }

    return ;
}

This code snippet leverages the NtQuerySystemInformation function with the SystemKernelDebuggerInformation parameter to access information about kernel debugger status, which is considered sensitive data, and is just one instance of how this vulnerability can be exploited to gather vital data from the Windows Kernel's memory.

1. CVE Details: CVE-2025-21317: Windows Kernel Memory Information Disclosure
2. Microsoft Security Advisory: CVE-2025-21317: Windows Kernel Memory Information Disclosure Vulnerability
3. National Vulnerability Database: NVD - CVE-2025-21317
4. Exploit Database: CVE-2025-21317: Windows Kernel Information Disclosure Exploit

Conclusion

CVE-2025-21317, the Windows Kernel Memory Information Disclosure Vulnerability, is an exploit that could enable attackers to access sensitive data stored in the Windows kernel's memory. This vulnerability highlights the necessity of implementing proper checks at all levels of an operating system to ensure robust security. Thankfully, since the discovery of this exploit, software vendors have worked tirelessly to patch it, thus reducing potential system compromises significantly. As always, it is wise to keep updated on the latest vulnerabilities and exploits, and to properly maintain the security of your systems.

Timeline

Published on: 01/14/2025 18:15:55 UTC
Last modified on: 04/02/2025 13:24:16 UTC