What is DNS spoofing and how is it avoided?

What is DNS spoofing and how is it avoided?
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Fri, 20/05/2022 – 09:37

What is DNS and DNS Server?

To fully understand DNS spoofing, it is important to understand DNS and DNS servers. For starters, every computer and server has a unique Internet Protocol (IP) address which is a numeric string ID that tells websites which computer the site is using. These digit string IDs are hard for people to remember, so instead we use domain names to keep track of the website we are on. The DNS “domain name system” is then what translates the domain name to the correct IP address. DNS servers (resolving name servers, root nameservers, top-level domain (TLD) name servers, and authoritative name servers) are then what enables the translation or lookup process between the domain name and the IP address.

The DNS lookup process works like this:

  1. Your web browser tries to find the IP address associated with the website you are trying to use.
  2. Your operating system will first look in the cache memory of the computer. A website you have visited before will likely have the IP address already stored on your computer.
  3. If your operating system cannot find the IP address on the computer, it queries the resolving name server, which is the first DNS server.
  4. The request goes through the DNS servers to find the corresponding IP address.
  5. The IP address is then sent back to the operating system, which sends it back to your web browser.
What is DNS spoofing?

DNS spoofing or poisoning is a cyberattack that uses DNS servers to give your web browser the wrong IP address and send you to a fraudulent website instead of the one you wanted to visit. DNS spoofing will mimic legitimate DNS server activity to send users to a malicious website, usually designed to look like the original site, but will steal confidential information. Whether through modified files or corrupted server data, attackers will send users to the wrong place and use this vulnerability. A variant of this type of attack is DNS cache poisoning. With this attack, your operating system and your computer will save the fraudulent IP address in the cache memory of your computer. Then when you try to extract the domain you want, it will continue to extract the malicious website instead.

DNS spoofing methods

There are several ways attackers can perform a DNS spoofing attack, but there are three that are the most common and therefore the most important to prepare for.

DNS hack

A DNS hijack occurs when an attacker uses the DNS servers themselves to send users to malicious websites. The attacker can take control of routers, redirect communications or even use malware on endpoints. Typically, an attacker will reconfigure the DNS servers so that all user requests through the servers are sent to the fraudulent IP address.

Fool the middle man

This type of attack occurs when an attacker puts something between an IP address request and the DNS servers. An attacker will intercept a DNS request before it can pass through the real DNS servers and instead return a fraudulent IP address to the computer. With the fraudulent IP address, the web browser then takes the user to the malicious website. Essentially, the DNS query interceptor is a man-in-the-middle that directs users to the wrong website.

cache poisoning

The other two attacks could potentially lead to cache poisoning, but there is an additional way for attackers to cache the wrong IP address in a computer. Email spam and ad spam can actually be used to embed the wrong IP address into computer memory. Attackers can send emails with links, and if a user clicks on the link, the link will direct them to a malicious website and poison their computer’s cache. Ad clicks can also be used in the same way to set up a DNS spoofing cache poisoning attack.

How DNS Spoofing Works

Attackers can use any of the three methods alone or in tandem to orchestrate a DNS spoofing cyberattack. Attackers will have different motives for their attacks, but most of them will follow a very similar pattern in how they orchestrate their attacks.

  1. Information gathering. Before an attacker launches an attack, they will collect information about your website and your organization. They will examine DNS servers, determine the average number of queries they handle, find the domain’s security precautions, notice vulnerabilities, and ultimately determine if there is a way to find a hole to launch an attack.
  2. Access access. To launch a DNS spoofing attack, attackers must have access to servers or other entry points where they can release corrupted DNS data or intercept queries. Usually an attacker doesn’t try to take control of the entire server, but rather finds a small hole where he can access files and requests.
  3. Launch of the attack. Once an attacker has access and knows what to expect, they will launch the DNS spoofing or poisoning attack.
The risks of DNS spoofing

Why do attackers use DNS spoofing? What are they trying to do? Here are some of the most common reasons attackers will want to use this type of cyber threat and DNS spoofing risks to be aware of:

  • Malware infection. Sometimes attackers send users to malicious websites that install malware on their devices. Then, when a user is directed by DNS spoofing to the wrong site, their computer gets infected, which can lead to many others being infected with the malware.
  • Data theft. Most cyber attackers seek user data that they can sell. Many DNS attacks spoof a shopping site. When users are redirected to the malicious website, they may enter their personal information thinking that they are on the site they wanted to access. Attackers can then sell this data.
  • Censorship. DNS spoofing sends users to different websites they intended to access, which means if someone doesn’t want you to go to a website, they can use DNS spoofing for you remove. Some governments use DNS spoofing as a means of censorship, such as the Great Firewall in China. DNS spoofing can be significant and costly.
How to Prevent DNS Spoofing

With these DNS spoofing risks in mind, it’s time to explore how to prevent DNS spoofing from happening in the first place. As with all cybersecurity, there is no perfect solution that can fully guarantee that no attacker will breach your defense. But there are steps you can take to protect your users and greatly reduce the risk of a DNS spoofing or poisoning attack. Here are some ways to reduce the risk of DNS spoofing:

  • DNS spoofing tools. There are tools designed specifically to help identify DNS spoofing attacks. Using these tools can give you confidence that someone is watching for these types of attacks. The downside is that it can be more expensive and time-consuming to use specialized tools and services.
  • Increased encryption. End-to-end encryption can make it much more difficult to duplicate your website’s TLS/SSL certificates and find vulnerabilities to launch an attack. Although not a perfect solution, incorporating increased encryption can be used along with many other preventative measures.
  • Use of DNSSEC. DNSSEC is a verified label that helps protect your website against DNS spoofing. It can be difficult to set up and keep all information private, so using this solution may require professional advice.
  • Maintain current and updated TLS certificates. Many people forget that TLS/SSL certificates are powerful tools for keeping your website secure. In fact, man-in-the-middle attacks are usually only possible because an attacker is able to strip a site of its TLS/SSL certificates. Using strong certificate management can prevent attackers from using DNS spoofing.

To be prepared against DNS spoofing and poisoning attacks, your solution can encompass several precautions. One of the most important preventive measures to take is to use proper TLS/SSL management support. Venafi is ready to help protect you against DNS spoofing with this voucher certificate management. Download our TLS/SSL Machine Identity Management Guide to start protecting your sites against DNS spoofing and poisoning.

In today’s internet and technology environment, cyberattacks are a constant and growing problem that every business and every website needs to be prepared for. Without the proper precautions and support, attackers can do real damage to your organization and your website. DNS spoofing or poisoning is one of the ways attackers can cause this harm. To help you understand how to prevent DNS spoofing, we’ll explain what it is, how it works, and what you can do about it.

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