Email Security

What Is IP Spoofing: How It Works, What It’s Used For, And How You Can Mitigate Its Impact

A look at IP spoofing: what it is, how it works, and what you can do to mitigate risks against your company.

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What Is IP Spoofing?

IP spoofing (or IP impersonation) is a cybercrime in which a threat actor creates Internet Protocol (IP) packets with a fake IP address with the intention of impersonating another computer system or to just hide their own identity online. It’s often a method used by attackers to instigate cyberattacks against their targets, with the intention of causing disruptions to web traffic, stealing information and data, or infiltrating networks.

How Does IP Spoofing Work?

To understand how IP spoofing works, we need to talk about network packets. Network packets are essentially data that is sent over networks. They are part of one large message that is broken down into smaller parts to make sure that they reach their destination easily. Think of it as small messages that create one large message. Any data that is sent over a network will be broken down and sent in these small packets. 

Network packets are made up of two main parts: the header and the body, which is referred to as the payload. Packet headers will contain user data and control information. The control information is what dictates how the packet is delivered. The packet header tells the server information about the packet and is what a server will see first. The header will tell the server where the packet came from (including sender IP address), its intended destination, the packet’s contents, and any other data that will help the packet get to said destination.

IP spoofing focuses on falsifying network packets, specifically the packet header – the bit that tells the server where it came from. The attack will use tools to change the source address, tricking the server into thinking the packet is from a trusted source and leading the server to accept it. As this works on such a technical level, it’s impossible for end users to realize an email is from a spoofed IP address.

Using A Trusted IP Address

Threat actors can spoof IP addresses into impersonating that of a trusted IP address to infiltrate secure networks. It’s especially effective in scenarios where companies have trust relationships between their machines and systems. Attackers can spoof an IP address from a trusted machine, meaning if they’re on the same network they could access their target without authentication.

Intercepting Packets

IP spoofing also needs to intercept a packet, swapping the IP header for the spoofed one. This can be done with a network sniffing tool, which analyzes data packets as they travel over networks. Network sniffer tools can be either software or hardware. While used by threat actors to commit IP spoofing, the tool is also used by admins to track network traffic via packets.

Why Is IP Spoofing Used?

Distributed Denial-of-Service Attacks And Masking Botnet Devices

IP spoofing is commonly used to instigate Distributed Denial-of-Service (DDoS) attacks against an intended target. These attacks aim to disrupt traffic to a server, overwhelming it by flooding it with internet traffic. Once the target is overwhelmed, this malicious traffic renders the server unavailable. It does this by using IP spoofing to generate fake requests to access a server, increasing their traffic output with what is actually a small request. IP spoofing can also be used by attackers specifically to overcome any network security measures that may have the original IP address blocked for whatever reason. Reasons for these attacks are usually revenge, activist, or blackmail motivated.

Despite being frequently used to attack targets, IP spoofing can be used for genuine purposes. IP spoofing and DDoS attacks are often employed by companies testing whether or not their website can handle large influxes of traffic.

In a similar vein, IP spoofing is also used to mask botnet devices during DDoS attacks. Botnets are a series of devices that are connected via the internet and have been infected with malware and are controlled by a third party. These infected devices, often unwittingly on behalf of the user, can instigate these attacks on a huge scale, rendering websites unavailable for extended periods of time.

Threat actors can use these devices to instigate attacks on their targets, usually by flooding them with data to get them to crash or sending malware and spam. IP spoofing will mask the IP address of the devices, meaning that targets cannot alert device owners to the fact their devices are being used as part of an attack. IP spoofing botnet devices also allows for these devices to bypass any security measures that try to prevent DDoS attacks through blacklisting malicious IP addresses.

Man-in-the-middle Attacks

Man-in-the-middle (MITM) is an attack method where the threat actor can situate themselves between two parties who are communicating with each other, intercepting and deciphering all communications sent between the two. It works with the attacker spoofing each of the parties’ addresses as they communicate with each other. Information sent reaches the attacker first, before the it is passed on to the intended recipient with a spoofed IP address, so the recipient is unaware the contents has been accessed by another first. As one piece of information passes over from one party to the next, the threat actor in the middle can either change the contents before passing it on to the recipient, or just record and let the information pass by.

These attacks are primarily for stealing data, eavesdropping, or disrupting the session, making it a serious threat for companies – especially to those which handle highly sensitive data and information such as financial data or patient information. MITM attacks present threat actors with further attack vectors to gain access to servers.

How You Can Protect Your Business

Spoofing was the 6th most prevalent form of cybercrime that was reported to the IC3 in 2020. While phishing, extortion, and data breaches topped the list for that year, it doesn’t make spoofing any less of a threat or any less damaging. Successful IP spoofing attacks can lead to data loss and security breaches that can damage your company and your brand.

There are preventative steps that can be taken by IT admins in order to detect and respond to suspicious activity by monitoring incoming traffic and prevent spoofed packets from accessing a network. As it’s a highly technical attack, technical approaches are needed, with little end-users being able to do so on their part.

Packet Filtering

Packet filtering is a firewall method that does exactly what it says – it filters incoming and outgoing IP packets. Filtering incoming packets is called Ingress filtering. It’s used to make sure that incoming packets really are coming from where they say they are. Ingress filtering is used in conjunction with egress filtering. Egress filtering examines outbound information, making sure packets only leave the network if they’re in line with admins’ pre-determined policies and that they are going to where they’re supposed to be.

Packet filtering specifically checks the source and IP address. The filtering will also check the source and destination protocols. This is done to make sure they match. Most routing devices will have filtering as an integrated capability, so making sure this is configured correctly is a vital step in mediating any potential IP spoofing-based attacks.

Network Attack Blocker

Network attack blockers work in conjunction with network firewalls. Firewalls authenticate IP addresses, making sure only authorized traffic is permitted, securing private networks. Network attack blockers authenticate the IP addresses of any incoming IP packets, allowing for them to detect any suspicious packets with IP addresses that don’t quite match. From there, the attack blocker will block the network activity by the IP address accessing your network.

Implementing Verification Methods

Implementing strong verification methods, even if devices are on a shared network but especially for all remote access, is a vital step in mitigating potential damage instigated by IP spoofing attacks. This can be done by installing multi-factor authentication for devices, as well as configuring so devices and users cannot be authenticated because of their IP address. Multi-factor authentication adds an extra sign-on step for users, in addition to their login credentials, to help them verify that they are who they say they are.

You can read more about multi-factor authentication and which products are the best ones for your business here:

The Top 11 Multi-Factor Authentication (MFA) Solutions For Business


IP spoofing is a serious cyberthreat that can be inconvenient at best through mild DDoS attacks, to catastrophic at worst through data breaches and malware attacks. While it can’t necessarily be prevented, admins can mitigate any potential damage by making sure that the right protocols and configurations are in place to prevent harm and minimize risk. In addition to making sure everything is configured correctly, implementing multi-factor authentication, and installing systems that include robust filtering policies, can help admins detect and respond to IP spoofing-based threats.