Having a single cybersecurity defense doesn’t guarantee total security as hackers continue to devise new ways to break through. They understand that launching direct attacks isn’t so effective anymore since advanced security mechanisms can detect them easily. Hiding behind legitimate networks through techniques such as ARP poisoning attacks makes their jobs easier.


With ARP poisoning, a cybercriminal can redirect your IP address and intercept your communications in transit without your knowledge. Here’s how this attack method works and how you can prevent it.

What Is an ARP Poisoning Attack?

Address Resolution Protocol (ARP) is a connectivity procedure that links an Internet Protocol (IP) address to the static physical address of a Media Access Control (MAC) over a Local Area Network (LAN). Since the addresses of the IP and MAC are of different compositions, they aren’t compatible. ARP reconciles this difference to ensure that both elements are in sync. Otherwise, they wouldn’t recognize themselves.

An ARP poisoning attack is a process whereby an intruder sends malicious content via a Local Area Network (LAN) to redirect the connection of a legitimate IP address to their MAC address. In the course of this, the attacker displaces the original MAC address that should connect to the IP address, allowing them to access messages that people send to the authentic MAC address.

How Does an ARP Poisoning Attack Work?

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Several networks can function on a Local Area Network (LAN) at the same time. Each active network gets a particular IP address which serves as its means of identification and differentiates it from others. When data from the various networks get to the gateway, the ARP sorts them accordingly, so each one goes straight to its intended destination.

The attacker creates and sends a false ARP message to the profiled system. They add their MAC address and the target’s IP address in the message. Upon receiving and processing the false ARP message, the system synchronizes the attacker’s MAC address with the IP address.

Once the LAN connects the IP address with the intruder’s MAC address, the intruder begins to receive all messages intended for the legitimate MAC address. They can eavesdrop on the communication to retrieve sensitive data in exchange, modify the communication by inserting malicious content to aid their intent, or even delete the data in transit, so the receiver doesn’t get it.

Types of ARP Poisoning Attacks

Cybercriminals can launch ARP attacks in two ways: Spoofing and Cache poisoning.

ARP Spoofing

ARP spoofing is a process where a threat actor forges and sends an ARP reply to the system they are targeting. One forged reply is all the intruder must send for the system in question to add its MAC address to the whitelist. This makes ARP spoofing easy to execute.

Attackers also use ARP spoofing to perform other kinds of attacks such as session hijacking where they take over your browsing sessions and Man-in-the-Middle attacks where they intercept communications between two devices connected to a network.

ARP Cache Poisoning

The poisoning in this kind of ARP attack stems from the attacker creating and sending multiple forged ARP replies to their target system. They do this to the point where the system is overwhelmed with invalid entries and can’t identify its legitimate networks.

The cybercriminal engineering the traffic commotion will seize the opportunity to redirect the IP addresses to their own systems and intercept communications passing through them. Threat actors use this ARP attack method to facilitate other forms of attacks like Denial of Service (DoS) where they flood the target system with irrelevant messages to cause a traffic jam and then redirect the IP addresses.

How Can You Prevent an ARP Poisoning Attack?

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ARP poisoning attacks have negative impacts on your system such as the loss of critical data, a dent in your reputation due to the exposure of your sensitive data, and even downtime should the attacker tamper with elements that drive your network.

If you don’t want to suffer any of the above implications, here are ways to prevent ARP poisoning attacks.

1. Create Static ARP Tables

ARP technology can’t automatically validate legitimate IP addresses with their MAC addresses. This avails cybercriminals the opportunity to forge ARP replies. You can fix this loophole by creating a static ARP table where you map all the authentic MAC addresses on your network to their legitimate IP addresses. Both components will only connect to and process their matching addresses, removing the opportunity for attackers to connect their MAC addresses to the network.

Building ARP static tables involves a lot of manual work which makes it time-consuming. But if you put in the work, you’ll prevent several ARP poisoning attacks.

2. Implement Dynamic ARP Inspection (DAI)

Dynamic ARP Inspection (DAI) is a network security system that verifies the ARP components present on a network. It identifies connections with illegitimate MAC addresses trying to redirect or intercept valid IP addresses.

DAI inspection checks all ARP MAC-to-IP address requests on the system and confirms that they are legitimate before updating their information on the ARP cache and passing them to the right channels.

3. Segment Your Network

Attackers execute ARP poisoning attacks, especially when they have access to all areas of a network. Segmenting your network means that the various components will be in different areas. Even when an intruder gains access to one part, there’s a limit to the control they have can since some elements aren’t present.

You can solidify your security by creating a static ARP table for each segment of your network. That way, it’s more difficult for hackers to break into a single area, let alone all areas.

4. Encrypt Your Data


Encryption may not have much impact in stopping hackers from infiltrating your network with ARP poisoning attacks, but it will prevent them from modifying your data if they get a hold of it. And that’s because encrypting data prevents intruders from reading it without the valid decryption key.

If the data attackers steal from an ARP poisoning attack is useless to them due to encryption, they can’t say their attack was successful.

Prevent ARP Poisoning Attacks With Authentication

ARP poisoning attacks thrive when there are no parameters to secure your network connectivity from intrusion. When you create a whitelist of networks and devices to approve, items that aren’t on the list will fail the authentication check and will not be able to enter your system.

It’s better to prevent threat actors from entering your system than deal with them when they are already in. They may cause severe damage before you can contain them.

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