How ARP Poisoning Works

ARP (Address Resolution Protocol) poisoning, also known as ARP spoofing, is a network attack in which an attacker alters the ARP cache of a target device on a local network. This attack allows the attacker to intercept, modify, or redirect network traffic between two or more devices without their knowledge. ARP poisoning can be used in various cyberattacks, including Man-in-the-Middle (MITM) attacks, sniffing sensitive data, and conducting other malicious activities. Here’s how ARP poisoning works and how to prevent it:

How ARP Poisoning Works:

ARP poisoning exploits the weakness in the way ARP operates. ARP is used to map an IP address to a physical MAC address within a local network. It’s a crucial component of network communication.

1. Initial ARP Request:

• When a device wants to communicate with another device in the local network, it sends an ARP request asking for the MAC address associated with the target’s IP address.
• All devices on the local network receive this request.

1. ARP Response:

• The device with the requested IP address responds with its MAC address.
• The requesting device updates its ARP cache with this information for future communication.

1. ARP Poisoning Attack:

• An attacker on the same local network sends fake ARP responses to the target device, claiming to be another device with a known IP address.
• The target device updates its ARP cache with the attacker’s MAC address, associating it with the legitimate IP address.

1. Traffic Diversion:

• The attacker can intercept and manipulate network traffic between the target device and other devices by posing as a legitimate intermediary. The attacker can capture sensitive information, modify data, or conduct other malicious actions.

Preventing ARP Poisoning Attacks:

Preventing ARP poisoning attacks can be challenging, but there are some steps you can take to mitigate the risk:

1. Use ARP Spoofing Detection Tools:

• Deploy network security tools and intrusion detection systems that can detect and alert you to ARP poisoning attempts.

1. Static ARP Entries:

• Configure static ARP entries on critical devices to ensure they always use the correct MAC address.

1. ARP Cache Timeout Settings:

• Configure ARP cache timeout settings to limit the impact of ARP poisoning. Shorter timeouts mean the cache is refreshed more frequently.

1. Network Segmentation:

• Segment your network to limit the impact of ARP poisoning attacks. Devices on different network segments are less susceptible to such attacks.

1. Implement Network Monitoring:

• Continuously monitor network traffic and devices for any unusual or suspicious activities.

1. Use Network Encryption:

• Implement encryption technologies such as VPNs or SSL/TLS for sensitive communications to protect data in transit.

1. Layer 2 Security:

• Employ network security mechanisms at the data link layer, including 802.1X authentication and port security.

ARP poisoning is a serious security concern in local network environments, and mitigating this attack requires a combination of network segmentation, monitoring, and security measures to protect your network and data from unauthorized access and manipulation.