ARP Poisoning, also known as ARP spoofing or ARP cache poisoning, is a cyber attack technique that exploits the Address Resolution Protocol (ARP) in a computer network. ARP is responsible for mapping an IP address to a corresponding Media Access Control (MAC) address, so that data packets can be correctly transmitted to the intended network device. An attacker can use ARP poisoning to intercept, modify, or disrupt communications between network devices.
How It Works:
- The attacker sends falsified ARP messages to the network, associating their MAC address with the IP address of a targeted device (such as a server or gateway).
- Other devices on the network treat the attacker’s MAC address as the legitimate one for the targeted IP address, updating their ARP tables accordingly.
- As a result, data packets that were meant for the targeted device are now sent to the attacker instead, potentially enabling them to eavesdrop, modify, or disrupt network traffic.
ARP poisoning can lead to serious security issues, including:
- Data leakage: Attackers can intercept sensitive data exchanged between devices on the network.
- Man-in-the-middle attacks: Attackers can modify data in transit, potentially inserting malicious content.
- Denial of Service (DoS) attacks: Attackers can render a targeted device unresponsive by flooding it with traffic or by dropping all packets bound for it.
Prevention and Mitigation:
Several strategies can help protect networks against ARP poisoning:
- Static ARP entries: Assign static IP-to-MAC address mappings to prevent attackers from forging ARP responses.
- ARP inspection tools: Use switches, firewalls, or Intrusion Detection/Prevention Systems (IDS/IPS) that support Dynamic ARP Inspection (DAI) or similar features to validate or filter suspicious ARP traffic.
- IPsec or SSL/TLS: Encrypt traffic between network devices with secure protocols like IPsec or SSL/TLS to mitigate eavesdropping or tampering risks.
- Regular monitoring: Continuously monitor network traffic and device ARP tables for anomalies or inconsistencies, possibly using Network Intrusion Detection Systems (NIDS) or other security tools.