What is ARP Spoofing? – ARP poisoning Attack

The ARP Poisoning, also known as ARP Spoofing, is a type of cyberattack that takes advantage of the ARP (Address Resolution Protocol). ARP is a protocol that maps an IP address to a MAC address within a local network. However, ARP lacks authentication mechanisms, and this is what the attack exploits.

The attacker sends fake ARP responses to a specific host on the network, thus linking the attacker’s MAC address to the IP address of another host, such as the network’s gateway. As a result, the target host sends all its network traffic to the attacker instead of the intended host.

ARP Spoofing / ARP Poisoning Diagram

ARP Poisoning Process –

Selection of Targets –
The first phase in an ARP Poisoning attack is choosing a target. This could be a specific device on the network, a group of devices, or a network device like a router. Routers are often targeted because a successful ARP Poisoning Attack against a router can disrupt traffic for an entire subnet.

Launching of Tools and Initiation of Attack –
The attacker uses a spoofing tool, such as Arpspoof or Driftnet, to start the attack. These tools have the ability to send out forged ARP responses. The attacker configures the tool with their MAC address and the IP addresses of the two devices they want to intercept traffic between. The forged responses tell both devices that the correct MAC address for each of them is the attacker’s MAC address. As a result, both devices start sending all their network traffic to the attacker’s machine, thinking it’s the other device they want to communicate with.

After successfully inserting themselves in the middle of the communication channel between the two devices, the attacker can then do various things with the incorrectly directed traffic. If the attacker chooses to inspect the traffic, they can steal sensitive information. If they decide to modify the traffic, they can inject malicious script. Finally, if they choose to block the traffic, they can perform a Denial of Service (DoS) attack, where they completely stop the communication between the two devices.

The attack exploits a fundamental weakness in the ARP — the lack of an authentication mechanism for ARP messages, allowing any device on the network to answer an ARP request, whether the original message was intended for it or not .

Types of ARP poisoning attacks:

Active ARP Poisoning

In active ARP poisoning, also known as ARP spoofing, the attacker sends forged ARP responses to the target devices on the network. The attacker pretends to be the legitimate device by associating their own MAC address with the IP address of the target device in the ARP cache of other devices. As a result, network traffic intended for the target device is redirected to the attacker’s machine. The attacker can intercept, modify, or block the traffic as desired.

Passive ARP Poisoning

In passive ARP poisoning, the attacker does not actively send forged ARP responses. Instead, they monitor the network and collect ARP cache information from legitimate devices. By passively listening to ARP requests and responses, the attacker can gather information about the IP-to-MAC address mappings of devices on the network. This information can be used for further attacks or reconnaissance purposes.

Both active and passive ARP poisoning attacks can be used for malicious purposes, such as eavesdropping on network traffic, performing man-in-the-middle attacks, or disrupting network communication. It is important to implement security measures to detect and prevent ARP poisoning attacks, such as using secure network protocols, implementing network segmentation, and regularly monitoring network activity for suspicious behavior.

Frequently asked questions (FAQ’s) on ARP poisoning

Q1: How does ARP poisoning work?

Answer:

ARP poisoning exploits the weakness in the ARP protocol, which lacks authentication. The attacker sends false ARP messages to the target devices, falsely associating their own MAC address with the IP addresses of other devices on the network. As a result, network traffic destined for those devices is diverted to the attacker’s machine.

Q2: What are the motivations behind ARP poisoning attacks?

Answer:

The motives behind ARP poisoning attacks can vary. Some common motivations include eavesdropping on network traffic to collect sensitive information, performing man-in-the-middle attacks for interception or modification of data, or causing network disruptions and denial of service.

Q: How can ARP poisoning attacks be detected?

Answer

Detection of ARP poisoning attacks can be challenging since the ARP protocol itself does not provide a built-in mechanism for detecting spoofed or manipulated ARP messages. However, there are some techniques to detect ARP poisoning, such as monitoring ARP caches, using network intrusion detection systems (IDS), or employing tools specifically designed for ARP poisoning detection.

Q: What are the preventive measures against ARP poisoning attacks?

Answer

Several strategies can help prevent ARP poisoning attacks, including:

– Implementing network segmentation to isolate critical devices.

– Configuring static ARP entries to bind IP addresses with MAC addresses.

– Employing cryptographic protocols (e.g., IPsec) for secure communication.

– Monitoring network traffic and analyzing ARP activity for anomalies.

– Implementing network access control mechanisms, such as 802.1X authentication.

Q5: Can ARP poisoning attacks be executed over wireless networks?

Answer

Yes, ARP poisoning attacks can be performed on wireless networks. In a Wi-Fi network, the attacker must be within range and connected to the same network as the target devices to execute ARP poisoning.