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What is IP Spoofing?

Spoofing is the online impersonation of a user, device, or client. It's frequently used to hide the source of attack communications during a cyberattack.

Your IP address determines your identification on the internet, whether you are an individual or a collective entity. This identity, however, is not as safe as we'd like it to be, and it is constantly at risk of being stolen and exploited. With your identity in hand, the criminal may not only get into your traffic and sensitive data but also perform massive cybercrimes in your name.

IP spoofing is the process of altering the source address of Internet Protocol (IP) packets in order to conceal the sender's identity, mimic another computer system, or both. It's a method that malicious actors frequently employ to launch DDoS attacks against a target device or the surrounding infrastructure.

Because Internet global routing is dependent on the destination IP address, source IP spoofing is feasible. Or, to put it another way, an Internet router in default mode (that is, with no extra policies implemented, such as reverse path filtering) passes packets from one interface to another by just searching up the destination IP address.

An application with adequate rights can change the source IP address field of an IP packet to any syntactically correct value, and the packet will be delivered through the network interface in the vast majority of situations and will reach the destination in many circumstances.

What is IP Spoofing

Figure 1. What is IP Spoofing

An incorrect source IP address may obstruct regular communications by preventing answers from the target application or intermediate nodes (e.g., ICMP responses) from reaching the sender. Attacks carried out with the spoofing method, on the other hand, do not rely on correctly configured communication channels. On the contrary, they make use of this functionality by redirecting response traffic to the destination designated by the forged source IP address.

How does IP Spoofing Work?

The hacker intercepts the TCP handshake before step 3, that is, before the source sends its SYN-ACK message, in the most basic IP spoofing attack. Instead, the hacker sends a bogus confirmation that includes their device address (MAC address) and the original sender's faked IP address. The recipient now believes they're interacting with the original sender, but they're actually communicating with a faked IP address.

When the source's IP address is changed to imitate the IP address of another authorized or legitimate source, this is known as an IP spoofing attack. This source could, for example, be a computer or system that is part of a valid and trustworthy network. The data is approved because the source appears to be legitimate. The cyber attacker can then modify the IP address header using a variety of IP spoofing tools. The receiver has no way of identifying and judging the address once it has been tampered with externally. This is due to the fact that most IP spoofing in network security occurs at the network level.

What are the Types of IP Spoofing Attacks?

When cybercriminals employ spoofed IP source addresses to impersonate trusted sources, it can be dangerous for a variety of reasons, including the following:

  • Unwitting victims of IP spoofing may have their personal information taken and utilized for nefarious purposes such as identity theft and other internet crimes.
  • IP spoofing attacks can flood business servers and websites, causing them to go down.

What types of attacks can be carried out via IP spoofing? To mention a few, here are four:

1. Non-Blind Spoofing

The attacker sends many packets to the target in blind spoofing. These cyber attackers typically operate outside of the local network's limits and are largely unaware of how data is transmitted on that network. As a result, before launching an attack, they usually focus on figuring out how the packets are read in order.

2. Blind Spoofing

The attacker and their target are both on the same subnet in non-blind spoofing. It allows them to sniff the network in order to figure out the packet sequence. Once the hacker has access to the sequence, they can bypass authentication by impersonating another known and legal machine.

3. Man-in-the-Middle Attack

A man in the middle (MITM) attack occurs when a perpetrator places himself in the middle of communication between a user and an application, either to eavesdrop or to imitate one of the parties, making it look as though legitimate information flow is taking place.

4. Denial-of-Service Attack

In these types of attacks, the attacker sends packets and messages to their target from a variety of devices. As a result, pinpointing the source of IP address spoofing in DoS attacks becomes extremely difficult. As a result of their inability to track the source of the attack, they are unable to block it.

How to Detect IP Spoofing?

IP spoofing is difficult to detect by end-users. These attacks happen at the network layer, which is Layer 3 in the Open Systems Interconnection communications model. There will be no external traces of meddling this way. Externally, the faked connection requests appear to be valid connection requests.

However, enterprises can utilize network monitoring technologies to do traffic analysis at network endpoints. The most common method is to use packet filtering.

Routers and firewalls frequently feature packet filtering technologies. They look for discrepancies between the packet's IP address and the desired IP addresses on access control lists (ACLs). They can also detect forged packets.

The two types of packet filtering are ingress and egress filtering:

  • Ingress filtering looks at the source IP header of incoming packets to verify if it matches an allowed source address. Any that don't match or show other questionable behavior is rejected. This filtering creates an access control list (ACL) containing allowed source IP addresses.
  • Outgoing data is examined via egress filtering. It looks for source IP addresses that aren't on the company's network. Insiders will not be able to launch an IP spoofing attack using this method.

How to Prevent IP Address Spoofing?

To begin, make sure your firewall and routers are configured appropriately and that forged traffic from the internet is not allowed to pass through. Firewall vendors have incorporated a configurable anti-spoofing defense mechanism to prevent the use of private (RFC 1918) addresses on the external interface for many years. Furthermore, any addresses used in the internal network range as the source should not be accepted by the external (internet-facing) interface. You can focus on the below-shared list to prevent IP spoofing successfully.

  • Use authentication that relies on the key exchange between your network's machines; something like IPsec will greatly reduce the possibility of spoofing.
  • Deny private IP addresses on your downstream interface via an access control list.
  • Both inbound and outbound traffic should be filtered.
  • Configure your routers and switches, if they support it, to reject packets pretending to come from within your local network but actually coming from outside.
  • Enable encryption sessions on your router to allow trustworthy hosts from outside your network to connect securely with your local hosts.

How to Protect Against IP Spoofing?

While early detection of an IP spoofing attack can be difficult, there are various steps you can take to safeguard your organization from the risks of IP spoofing.

  1. Filtering of Packets: Every device or user attempting to join a network has their IP packets examined by packet filtering (this can be ingress to monitoring incoming communications or egress to monitor outgoing communications). This procedure examines each IP packet's header, which contains the IP address, in particular, to ensure that it matches the source and that everything appears to be in order. If anything appears to be wrong, the packet will be unable to finish the connection.
  1. Public Key Infrastructure (PKI) Authentication: Public key infrastructure (PKI) is a standard approach for authenticating people and devices that relies on a public and private key combination. The private key can encrypt communications and authenticate the validity of a user/device, while the public key can decode them. Importantly, these authentication methods employ asymmetric encryption, which means that each key in a pair is distinct from the other. This strategy makes determining the private key exceedingly difficult for hackers and is quite successful at blocking popular types of IP spoofing attacks, such as the man in the middle attack.
  1. Firewalls and Network Monitoring: The process of closely tracking network activity to check for anything suspect is known as network monitoring. While this may make it more difficult to prevent hackers from getting access through IP spoofing, because that strategy is supposed to hide their presence, it can help detect malicious activity early and stop the damage from spreading. In the meanwhile, setting up a network firewall is another technique to validate IP addresses and filter out any suspicious traffic that could be prone to IP spoofing.
  1. Security Awareness Training: Finally, security training for genuine network users can aid in the prevention of IP spoofing-related losses. Users might be told not to respond to emails that ask them to click on a link to modify their login details, for example. To take any action, go straight to the sender's website. While this form of training can be beneficial, it's crucial to remember that it's merely a kind of defense in depth strategy against harm. This training is not a deterrent since, by the time it is needed, a hacker has already carried out a successful IP spoofing operation and acquired access to particular systems.

What are Examples of IP Spoofing?

Here's a real-life example of an IP spoofing attack that demonstrates how the process works. Here's what happened to GitHub, a code hosting platform, on Feb. 28, 2018.

A huge DDoS attack was launched against GitHub, which was carried out by impersonating GitHub's IP address and delivering data to many servers. The data returned to GitHub was then amplified by a factor of 50 on those servers. Due to the increased load, GitHub's website was temporarily unavailable for 10 minutes.

Tsutomu Shimomura Case; On December 25, 1994, hacker Kevin Mitnick used IP spoofing to attack rival hacker Tsutomu Shimomura's computers. Mitnick took advantage of Shimomura's X terminal computer's trust connection with the server by studying the pattern of TCP sequence numbers that the computer-generated. He sent SYN requests to the computer from fake IP addresses that were routable but inactive. The computer was unable to respond to the queries, and its memory became overburdened with SYN requests. SYN scanning is the name for this approach.

Is IP Spoofing Illegal?

When used for non-malicious objectives, such as business website testing, IP spoofing is not illegal. When used to gain access to or steal sensitive data from another person or company with the aim to perpetrate crimes such as identity theft or other frauds, IP spoofing is illegal.

Can IP spoofing be Traced?

Because IP spoofing occurs at the network level, there is no visible evidence of interference from the outside. Consider a DoS attack in which spoofed packets are sent via botnets or networks of infected machines. IP spoofing attacks can be difficult to trace since they are automated by botnets including thousands of computers.