Host Logical Network Segregation Weakness - Proof of Concept (PoC)

A demonstration of network segmentation bypass through layer 2 adjacency despite logical subnet separation.

📖 Description

This repository demonstrates a network architecture vulnerability where:

• Two or more devices reside on different IP subnets (logical separation)
• But share the same physical broadcast domain (layer 2 adjacency)
• Allowing potential bypass of network access controls

🔍 Vulnerability Details

Technical Context
Traditional network security often relies on IP-based filtering (layer 3) while neglecting physical layer controls. When devices in separate subnets share the same broadcast domain:

1. ARP Protocol Exposure: Devices can discover each other via layer 2 ARP requests
2. MAC Address Communication: Direct communication possible using MAC addresses
3. VLAN Hopping Risk: Potential gateway spoofing between subnets

Impact

• Bypass firewall rules between subnets
• Potential lateral movement paths
• Violates PCI DSS Requirement 1.2.1 ("Implement subnet separation")

🧪 Proof of Concept

Prerequisites

• Kali Linux or similar distro
• Root privileges
• Nmap + tcpdump installed
• Network access to target subnet

Manual Verification Steps

1. ARP Discovery

sudo arp-scan -I eth0 172.21.4.0/24