Domain Name System (DNS) spoofing is a popular cyberattack that redirects users to malicious domains mimicking legitimate websites.

It's a clever tactic that can easily go unnoticed if you don't know what to look for. That's why it's best to take precautionary measures to prevent such attacks from occurring in the first place.

But how does DNS spoofing work? How can you detect it? How do you prevent it?

That's exactly what this article will explore.

What is DNS Spoofing?

DNS spoofing, often called DNS cache poisoning, is a cyberattack where DNS records are manipulated to redirect web traffic to malicious and fraudulent websites. This allows them to intercept sensitive data, install malware, and more. DNS spoofing can result in severe risks to data security and online privacy for individuals, organizations, and entire networks.

In reality, DNS spoofing and DNS poisoning are two separate things. However, both terms are often used interchangeably. Let's see how they differ.

DNS spoofing vs DNS poisoning

DNS poisoning is the act of compromising and manipulating DNS data, whereas DNS spoofing is the final result where users are redirected to a malicious domain via a poisoned cache. DNS cache poisoning is the method, and DNS spoofing is the result. These days, both terms are used synonymously, namely because the result is always the same.

How does DNS spoofing work?

In short, attackers alter a domain's corresponding IP address in a DNS server, which results in the DNS server caching that IP address as legitimate. Therefore, when a user sends a DNS request for that particular domain, the compromised DNS server returns the incorrect IP address, thus connecting the user to a fraudulent website.

This is possible due to the vulnerability of the DNS protocol. Unless you already have adequate security measures, all your DNS resolver queries and responses will be unencrypted, meaning they can be read and intercepted fairly easily through DNS software flaws, unpatched updates, or misconfigurations.

Once the attacker has access to the DNS resolver's cache or server, they can modify the stored IP addresses with malicious ones, poisoning the DNS cache.

These DNS systems cannot differentiate between a legitimate IP address and a fake one, meaning that the poisoned DNS cache will now store a spoofed entry and direct users to the fake website instead of the legitimate one.

For instance, they may spoof your favorite social media platform's IP address. This means that whenever you – or anyone else using that DNS server – try to access that social media site, you will be redirected to the attacker-controlled website instead of the real one.

DNS spoofing attacks are particularly dangerous since attackers can affect many users in one sweep, and it can easily go undetected.

What is DNS caching?

DNS servers and resolvers store (cache) data to speed up the resolution process and reduce network traffic. When you query for a specific domain, the DNS server will first check its cache for the IP address. If the information is cached, the server can return the DNS query immediately without going through authoritative DNS servers. If this caching system is manipulated, it can expose you to DNS spoofing attacks since incorrect IP addresses will be stored on servers.

What are the different types of DNS Spoofing attacks?

The most common DNS spoofing attacks are man-in-the-middle attacks, DNS server hijacking, and manipulating Time-To-Live values. All of these can expose your device and networks to malicious actors.

Man-in-the-Middle attack

As the name suggests, man-in-the-middle attacks are when an attacker intercepts communication between users and the server. By doing so, attackers can tamper with DNS requests and responses, and redirect you toward a malicious website instead of your intended domain.

DNS server hijacking

DNS server hijacking, also known as DNS server compromise, occurs when the attacker compromises authoritative DNS servers responsible for hosting domain data. This unauthorized access to DNS servers allows them to modify DNS records, manipulate DNS responses, and reconfigure the server to return a malicious IP address.

Manipulating Time-To-Live (TTL) values

Your DNS server's cache has a Time-To-Live (TTL) value, which is the length of time that the server stores a domain’s IP address before it has to process the entire query again.

Attackers often modify the TTL values to a longer time frame, meaning that users looking to access a particular domain will be redirected to the malicious IP address for longer. This maximizes their exposure to as many victims as possible.

What are the risks of DNS spoofing?

There are four main risks of DNS spoofing: data breaches, malware and ransomware infection, censorship, and legal or regulatory consequences. Let's examine them in more detail.

Data breaches

Perhaps the most common reason for DNS spoof attacks is data theft. Sensitive data can be extremely lucrative for attackers, whether it's an organization's or an individual's data. Examples include company records, personal information, banking details, credit cards, and passwords for logins.

Here’s a real-world example. Suppose you want to log in to your online banking account. An attacker can create a fake website that looks exactly like your bank's and, using DNS spoofing, redirect users to a fake website instead of the real one.

Without knowing you've been duped, you will enter your online banking details onto the website. This information goes directly to the attacker, who can then access your online banking account using your login details, allowing them to send or withdraw funds and engage in financial fraud.

Malware and ransomware distribution

DNS spoofing attacks redirect users to malicious websites that host malware, ransomware, and other software. By tricking users into downloading and executing infected files, attackers can compromise their device and network and manipulate it as they wish.

This can be particularly dangerous for organizations where one exposed device can lead to the entire IT infrastructure being attacked.

Enforce censorship

DNS spoofing is also used to enforce censorship. For instance, governments like China manipulate DNS caches and servers to block access to outlawed IP addresses, domains, and services. However, it's not just limited to governments. Malicious actors can also prevent users from accessing particular websites to control their browsing habits.

Not only can DNS spoofing attacks expose organizations to data theft and malware, but they can also face legal or regulatory consequences for failing to maintain adequate cybersecurity standards and protect sensitive information.

For instance, businesses operating in the European Union must comply with General Data Protection Regulation (GDPR) laws, and American organizations in the healthcare industry must abide by the Health Insurance Portability and Accountability Act (HIPAA).

Failure to do so can result in hefty fines, legal liabilities, and severe reputational damage.

How to detect a DNS spoofing attack?

Detecting a DNS spoofing attack can be challenging as it requires constant monitoring of your DNS entries and requests. But, establishing your baseline DNS behavior is crucial in spotting an attack.

Think of it like tracking your weight loss without knowing your starting weight – you have nothing to compare your current weight to and won't know if you've succeeded.

Once you have determined the DNS behavioral patterns of your organization's users, you can identify anomalies indicative of a DNS spoofing attack. Here are some tell-tale signs to look out for:

  • Unusual DNS resolution patterns: Monitoring your DNS queries can help identify discrepancies in your DNS requests, such as spikes for a specific domain, high query response times, or repeated queries for non-existent domains.
  • Examining DNS cache: Regular audits of your DNS resolver cache will help identify inconsistencies in resolved IP addresses for known domain names, differences between cached records and authoritative DNS data, and unexpected changes in TTL values.
  • DNSSEC validation: If you have DNSSEC enabled, spoofed DNS responses without valid signatures will be flagged.

How to prevent a DNS spoofing attack?

There are various ways to prevent DNS spoofing attacks, such as enabling Domain Name System Security Extensions (DNSSEC), DNS encryption, conducting regular updates, and using a VPN and secure DNS resolver.

Enable Domain Name System Security Extensions (DNSSEC):

DNSSEC is a suite of extensions that provide integrity to your DNS data. It does this by using cryptographic authentication to verify that all data received by your DNS resolver has not been manipulated or tampered with. If it has, the domain will be prevented from resolving on your device, thus protecting you from accessing a potentially malicious website.

DNS Encryption

DNS encryption ensures that DNS queries and responses between clients and resolvers cannot be viewed or changed in transit by outside parties. It transfers DNS data using protocols such as DNS-over-TLS (DoT) or DNS-over-HTTPS (DoH).

It ensures that you communicate with a legitimate DNS server, preventing attackers from analyzing or intercepting your DNS queries and thus mitigating the risks of DNS server hijacking.

Conduct regular updates

DNS spoofing attacks exploit weaknesses in your security protocol. These weaknesses are often created when there is a gap between modern attack methods and your security measures. That's why keeping your operating system, software, and servers up to date with the latest patches is important so you are constantly protected against the latest cyberattacks.

Use a Virtual Private Network (VPN)

VPNs are an effective security measure that shields you from external threats. They bypass your ISP's local DNS server and tunnel DNS queries to a private DNS server in your chosen location.

This private DNS server is often better protected against cyber threats like DNS spoofing since it uses end-to-end encryption for all queries and responses. This ensures that your DNS traffic is securely transmitted and protected from prying eyes and manipulation.

Use a secure DNS resolver

A customizable DNS resolver is crucial to prevent DNS spoofing attacks and bolster your overall security protocol. Private DNS resolvers are seen as a one-stop shop for all DNS protection. They often include many prevention methods mentioned in this article, such as DNSSEC, DNS encryption, and analytics to monitor DNS records.

They also have active malware blocking and come with DNS filtering capabilities that allow you to tailor your security protocol to your specific needs, such as blocking specific domains or services from being resolved on your network and devices.

The added benefit is that you won't have to worry about updating your DNS software since your DNS resolver will handle it all for you.

Conclusion

DNS spoofing is a dangerous cyberattack that can cause lasting damage to your network. It can lead to data breaches, malware and ransomware infections, and result in legal or regulatory consequences.

However, the most effective security measure against such attacks is to use all – or as many – of the prevention tactics mentioned in this article, such as enabling DNSSEC, using a secure DNS resolver, and encrypting all your traffic.