An Introduction to IP Spoofing (and How to Prevent It)

Identity theft is always a threat, regardless of the medium. So-called “IP spoofing” is a common way for malicious users to gain quick credibility for their hacking attempts.

Given that every computer and server has a unique identifier (an “internet protocol” — or IP — address), almost anyone using the internet could be vulnerable. IP spoofing is a way to “fake” the appearance of a source address (such as an email address) as an impersonation technique. It can come in various forms, so you have to be on your guard.

Throughout this post, we will talk about IP spoofing, what it is, why you’re a target, and more. We’ll also talk about some of the most common IP spoofing attacks you will come up against, as well as some legitimate uses for IP spoofing.

What Is IP Spoofing?

In a general sense, IP spoofing takes a portion of the data you send over the internet and makes it seem as though it’s from a legitimate source. IP spoofing is a wide-ranging term for many different attacks:

• IP address spoofing: This is a straightforward obfuscation of the attacker’s IP address to conduct denial-of-service (DoS) attacks, and more.
• Domain name server (DNS) spoofing: This will modify the source IP of the DNS to redirect a domain name to a different IP.
• Address resolution protocol (ARP) spoofing: An ARP spoofing attempt is one of the more complex attacks. It involves linking a computer’s media access control (MAC) address to a legitimate IP using spoofed ARP messages.

To get more technical, IP spoofing takes the data and changes some identifiable information at a network level. This makes spoofing almost undetectable.

For example, take a DoS attack.

This uses a collection of bots using spoofed IP addresses to send data to a particular site and server, taking it offline. Here, spoofing the IP makes the attack difficult to detect until it’s too late, and it’s similarly hard to trace after the fact.

Machine-in-the-middle (MITM) attacks also utilize IP spoofing because the MITM approach relies on faking trust between two endpoints. We’ll talk more about both of these attacks in greater detail later.

How IP Spoofing Happens

To better understand IP spoofing, let’s give you some context on how the internet sends and uses data.

Every computer uses an IP address, and any data you send is broken into many chunks (“packets”). Each packet travels on an individual basis. Then once they reach the end of the chain, they’re reassembled and presented as a whole. Moreover, every packet also has its identifiable information (a “header”) that will include the IP address from both the source and the destination.

In theory, this is supposed to ensure that data arrives at a destination free from tampering. However, this isn’t always the case.

IP spoofing uses the source IP header and changes some of the details to make it appear as though it’s genuine. As such, this can breach even the most stringent and secure of networks. The result is that web engineers often try to find new ways to protect information traveling across the web.

For example, IPv6 is a newer protocol that builds encryption and authentication. For end-users, secure shell (SSH) and secure socket layers (SSL) help mitigate attacks, but we’ll discuss why this can’t eradicate the problem later. The greater number of encryption steps you implement, the better you can protect your computer, in theory at least.

It’s also worth noting that IP spoofing is not an illegal practice, which is why it’s prevalent. There are lots of legitimate uses for IP spoofing that we’ll discuss in another section. As such, while the IP spoofing itself gets a hacker’s foot in the door, it might not be the only technique used to breach trust.

Why Your IP Is a Target for Spoofing

Taking all moral and ethical considerations aside, another’s user identity has immense value and worth. After all, there are many bad actors who, given the opportunity, would gladly use someone else’s identity to obtain something, free from moral repercussions.

Spoofing IP addresses is a high-value pursuit for many malicious users. The act of IP spoofing doesn’t hold much value, but the opportunities you’ll gain could be the jackpot.

For example, through IP spoofing, a user could impersonate a more trusted address to gain personal information (and more) from an unsuspecting user.

This can also have a knock-on effect when it comes to other users too. A hacker doesn’t need to spoof the IP of every target — they only need one to breach the defenses. By using these unearned credentials, the same hacker can also gain the trust of others in the network too and lead them to share personal information.

As such, the IP itself isn’t valuable. However, depending on what’s done with the spoofed IP, the payoff can be huge, and the potential for access to other systems through IP spoofing isn’t insignificant either.

3 Most Common Types of Attacks from IP Spoofing

IP spoofing lends itself well to certain types of attacks. Let’s go over three next.

1. Masking Botnets

A botnet is a network of computers that an attacker controls from a single source. Each of these computers runs a dedicated bot, which carries out the attacks on the bad actor’s behalf. You’ll find that the ability to mask botnets wouldn’t be possible without IP spoofing.

In normal circumstances, hackers gain control through infection, such as malware. The use of botnets can help a malicious user execute spam assaults, DDoS attacks, ad fraud, ransomware attacks, and much more. It’s a versatile way to carry out targeted skirmishes against other users.

Part of the reason for this is IP spoofing. Each bot in the network often has a spoofed IP, making the malicious actor challenging to trace.

The main benefit of spoofing IPs here is to evade law enforcement. However, this isn’t the only one.

For example, using botnets with spoofed IPs also stops the target from notifying owners of the problem. For starters, this can prolong the attack and let the hacker “pivot” the focus onto other marks. In theory, this could result in an attack running on an infinite basis to maximize the payoff.

2. Direct Denial of Service (DDoS) Attacks

If a site goes down due to excess and overwhelming malicious traffic on the server, this is a DDoS attack. It can be crippling for any site owner, and there are many ways to mitigate the effects.

This covers several related spoofing attacks and techniques that combine to create the entire assault.

DNS Spoofing

First, a malicious user will look to DNS spoofing to infiltrate a network. A malicious actor will use spoofing to alter the domain name associated with the DNS to another IP address.

From here, you could carry out any number of further attacks, but malware infection is a popular choice. Because it essentially diverts traffic from legitimate sources to malicious ones without detection, it’s easy to infect another computer. From there, more machines will succumb to infection and create the botnet to carry out the DDoS attack efficiently.

IP Address Spoofing

After DNS spoofing, an attacker will carry out other IP address spoofing to help obfuscate the individual bots within the network. This often follows a process of perpetual randomization. As such, the IP address never stays the same for too long, which makes it practically impossible to detect and trace.

This network-level attack is impossible for an end-user to detect (and stumps many server-side experts too). It’s an effective way to carry out malicious assaults without consequence.

ARP Poisoning

ARP spoofing (or “poisoning”) is another way to conduct DDoS attacks. It’s much more complex than the brute force method of masking botnets and IP spoofing, yet it incorporates them both to carry out an attack.

The idea is to target a local area network (LAN) and send through malicious ARP data packets to change the set IP addresses in a MAC table. It’s an easy way for an attacker to gain access to a large number of computers at once.

The goal of ARP poisoning is to channel all of the network traffic through an infected computer, then manipulate it from there. This is simple to do through the attacker’s computer, and it lets them choose between a DDoS or a MITM attack.

3. MITM Attacks

Machine-in-the-Middle (MITM) attacks are particularly complex, highly effective, and utterly catastrophic for a network.

These attacks are a way to intercept the data from your computer before it gets to the server you connect to (say, with your web browser). This lets the attacker interact with you using fake websites to steal your information. In some cases, the attacker is a third party that intercepts the transmission between two legitimate sources, which increases the effectiveness of the attack.

Of course, MITM assaults rely on IP spoofing as there needs to be a breach of trust without the user being aware. What’s more, there’s greater value in carrying out a MITM attack compared to others because a hacker can continue to collect data over the long term and sell it to others.

Real-world cases of MITM attacks show how IP spoofing comes into play. If you spoof an IP address and gain access to personal communication accounts, this lets you track any aspect of that communication. From there, you can cherry-pick information, route users to fake websites, and much more.

On the whole, a MITM attack is a dangerous and highly lucrative way to obtain user information, and IP spoofing is a central part of it.

Why IP Spoofing Is Dangerous for Your Site and Users

Because IP spoofing is something that happens at a low network level, it’s a danger to almost every user on the internet.

Phishing and spoofing go hand-in-hand. And a good spoofing attack won’t present as a phishing attempt. This means users will have no indication to be wary and might hand over sensitive information as a result.

Business-critical elements will be a prime target, such as security systems and firewalls. This is why site security is a number one concern for many. Not only do you need to implement enough functionality to mitigate an attack, but you also need to ensure that users of your network are vigilant and use good security practices.

 

 

However, one aspect of IP spoofing makes curbing it less straightforward: The technique has many legitimate use cases across the web.

Legitimate Uses For IP Spoofing

Because IP spoofing has lots of non-malicious use cases, there’s little you can do to stop others from using it.

For example, thousands of “ethical hackers” look to test systems for companies. This type of ethical hacking is a sanctioned system breach, designed to test security resources and strength.

This will follow the same process as malicious hacking. The user will carry out reconnaissance work on the target, gain and maintain access to the system, and obfuscate their penetration.

You’ll often find that unethical hackers convert to ethical types and find employment with companies they may have considered a target in the past. You can even find official exams and certifications to help you gain the proper credentials.

Some companies will also use IP spoofing in simulation exercises unrelated to system breaches. For example, mass mail-outs are a good use case for thousands of IP addresses, and they will all need to be created through (legitimate) spoofing.

User registration tests use IP spoofing to simulate the results too. Any situation where you need to simulate many users is an ideal case for ethical IP spoofing.

Why You Can’t Prevent IP Spoofing

Because spoofing is so tricky to spot, and because the nature of the method is to hide a true identity, there’s little you can do to prevent it from happening. However, you can minimize the risk and negate the impact.

It’s important to note that an end-user (i.e. the client-side machine) can’t stop spoofing in any way. It’s the job of the server-side team to prevent IP spoofing as best they can.

There are a few ways to add roadblocks between a hacker and a potential target. Some mentioned so far include:

• Using a more secure protocol, such as IPv6
• Ensuring the user base implements good individual security when using the site and network
• Implementing SSL and SSH on your site

However, there’s more you can do. For example, you can use a dedicated web application firewall (WAF) such as Sucuri, which will help to “build high walls” around your site.

You can also implement public critical infrastructure (PKI) to help authenticate users and associated data. This relies on a private and public key combination to encrypt and decrypt data. Because of the nature of encryption, it’s much more challenging for hackers to breach.

Network monitoring is a basic technique that can also help you spot the signs of IP spoofing or related attacks. This can take many forms, but the better you know your system, the greater the chance to spot malicious attacks.

Packet filtering can help to combat IP spoofing attempts too. “Ingress” and “egress” filtering looks at the source headers for incoming and outgoing communications. If something doesn’t pass that filter, it won’t then affect users within the network.

Finally, deep packet inspection (DPI) is a similar technique that’s as effective. This, along with the other methods here, can even be combined to help shore up a network or server.

Summary

Your IP address is unique to you, as it is for every computer in use today. That address helps to achieve many tasks, such as authentication, encryption, and more. By extension, this makes almost any IP address a target for would-be hackers or criminals.

IP spoofing fakes the legitimacy of an address and uses it to breach secure networks for further gain.

Fixing IP spoofing is something out of the control of the end-user, and it can be difficult for sysadmins to handle as well. Overall, you can only mitigate the impact IP spoofing has on your network rather than eradicate it in total.

Even so, there are a lot of roadblocks you can put in the way of a potentially malicious user. Typical encryption methods help, as does a good firewall and network monitoring strategy.

Are you a victim of IP spoofing, and if so, how have you resolved the situation? Share your thoughts in the comments section below!