In an ARP Spoofing attack, a hacker sends out fake ARP (Address Resolution Protocol) messages to trick other devices into believing they’re talking to someone else. The hacker can intercept and monitor data as it flows between two devices.

Cybercrimes have increased alarmingly due to the tremendous growth in the use of computers and networks for communication. Hackers and unethical attacks on networks provide a continuing threat to take information and cause digital mayhem.

In the past few months, we’ve seen the term “ARP spoofing” come up quite a bit in the news, is a technique that allows hackers to intercept traffic between two devices on a network.

What is ARP?

What is ARP? ARP stands for Address Resolution Protocol. It is a protocol used to map a network address, such as an IP address, to a physical (MAC) address on a local network. This is necessary because IP addresses are used for routing packets at the network layer, while MAC addresses are used for actually forwarding the packets on a specific link. ARP allows a device to determine the MAC address of another device on the same network, based on its IP address.

When a device wants to communicate with another device on the same network, it needs to know the MAC address of the destination device. ARP allows the device to broadcast a message on the local network, asking for the MAC address corresponding to a specific IP address. The device with that IP address will respond with its MAC address, allowing the first device to communicate directly with it.

ARP is a stateless protocol, meaning that it doesn’t maintain a table of mapping between IP and MAC addresses. Each time a device needs to communicate with another device on the network, it sends an ARP request to resolve the other device’s MAC address.

It’s worth mentioning that ARP is used in IPv4 networks, in IPv6 networks, a similar protocol is called Neighbor Discovery Protocol (NDP).

How Does an ARP Spoofing Work?

An ARP spoofing attack can be executed in one of two ways.

In the first method, a hacker will take their time waiting to access the ARP requests for a particular device. An immediate answer is sent following receipt of the ARP request. The network won’t instantly recognize this strategy because it is covert. In terms of impact, it doesn’t have much negative effect, and its reach is very narrow.

In the second method, hackers spread an unauthorized message known as “gratuitous ARP.” This delivery method might have an immediate impact on numerous devices at once. But remember that it will also generate a lot of network traffic that will be challenging to manage.

Who Uses ARP Spoofing?

Hackers have used ARP spoofing since the 1980s. Hacker attacks can be deliberate or impulsive. Denial-of-service assaults are examples of planned attacks, whereas information theft from a public WiFi network is an example of opportunism. These assaults may be avoided, but they are regularly carried out since they are simple from a technical and cost standpoint.

ARP spoofing, however, can also be carried used for honorable objectives. By deliberately introducing a third host between two hosts, programmers can use ARP spoofing to analyze network data. Ethical hackers will replicate ARP cache poisoning attacks to ensure networks are secure from such assaults.

What Is the Aim of an ARP Spoofing Attack?

The main aims of ARP spoofing attacks are:

to broadcast several ARP responses throughout the network
to insert fake addresses into switch MAC address tables
to incorrectly link MAC addresses to IP addresses
to send too many ARP queries to network hosts

When an ARP spoofing attack is successful, the attacker can:

Continue routing the messages as-is: Unless sent over an encrypted channel like HTTPS, the attacker can sniff the packets and steal the data.
Perform session hijacking: If the attacker obtains a session ID, they can access the user’s active accounts.
Distributed Denial of Service (DDoS): Instead of using their machine to launch a DDoS attack, the attackers might specify the MAC address of a server they wish to target. The target server will be inundated with traffic if they carry out this attack against multiple IP addresses.
Change communication: Downloading a harmful webpage or file onto the workstation.

How To Detect ARP Spoofing?

To detect ARP Spoofing, check your configuration management and task automation software. You can locate your ARP cache right here. You can be the target of an attack if two IP addresses have the same MAC address. Hackers frequently employ spoofing software, which sends messages claiming to be the default gateway’s address.

It is also conceivable that this malware convinces its victim to replace the default gateway’s MAC address with a different one. You will need to check the ARP traffic for any strange activity in this situation. Unsolicited messages claiming to own the router’s MAC or IP address are usually the odd type of traffic. Unwanted communication can therefore be a symptom of an ARP spoofing attack.

How To Protect Your Systems from ARP Spoofing?

ARP poisoning can be avoided in several ways, each with advantages and disadvantages.

ARP Static Entries

Only smaller networks should use this method due to its significant administrative burden. It entails adding an ARP record each computer for each machine on a network.

Because the computers can ignore ARP replies, mapping the machines with sets of static IP and MAC addresses helps to prevent spoofing attempts. Unfortunately, using this method will only shield you from easier assaults.

Packet Filters

ARP packets contain the sender’s and receiver’s IP addresses’ MAC addresses. These packets are sent over Ethernet networks. Packet filters can block ARP packets that do not contain valid source or destination MAC addresses or IP addresses.

Port Security Measures

Port security measures ensure that only authorized devices can connect with a particular port on a device. For example, suppose a computer has been allowed to connect with HTTP service on port 80 of a server. In that case, it will not allow any other computer to connect with HTTP service on port 80 of the same server unless they have been authorized previously.

VPNs

Virtual Private Networks (VPNs) provide secure communications over the internet. When users use VPNs, their internet traffic is encrypted and tunneled through an intermediary server. The encryption makes it very difficult for attackers to eavesdrop on communications. Most modern VPNs implement DNS leak protection, ensuring no traffic is leaked through your DNS queries.

Encryption

Encryption is one of the best ways to protect yourself from ARP spoofing. You can use VPNs or encrypted services such as HTTPS, SSH, and TLS. However, these methods are not foolproof and do not provide strong protection against all types of attacks.

Wrapping Up

Combining prevention and detection technologies is the ideal strategy if you want to protect your network from the risk of ARP poisoning. Even the most secure environment may come under attack since the preventative strategies frequently have faults in specific circumstances.

If active detection technologies are also in place, you will be aware of ARP poisoning as soon as it starts. You can typically stop these assaults before much damage is done if your network administrator responds quickly after being informed.

In protecting against other types of spoofing attacks like direct-domain spoofing, you may use a DMARC analyzer to authorize senders and take action against bad emails.

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Ahona Rudra

Domain & Email Security Expert at PowerDMARC

Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.

ARP Spoofing: What Is the Aim of an ARP Spoofing Attack?