DNS Cache Poisoning and DNS Spoofing

DNS Cache Poisoning and DNS Spoofing

DNS poisoning and spoofing is a cyberattack that exploits vulnerabilities in DNS servers to redirect traffic from legitimate servers to fake ones. Once exposed to a fake page, you may be puzzled about how to fix the problem, even though you’re the only one who can do it. Therefore, you need to know precisely how it works to protect yourself. DNS spoofing and resulting DNS cache poisoning are some of the most misleading cyber threats. Without a basic understanding of how web surfing works, you may be fooled into thinking that the website itself is hacked. More likely, though, it could just be your hacked device. Unfortunately, cybersecurity kits can only stop some of the threats associated with DNS spoofing.

What is a DNS Server?
What is a DNS Server?

What is a DNS Server?

DNS means “domain name system”. But before we explain DNS servers, it is essential to clarify the terms related to this topic. Now that we’ve established the definition of DNS and have a basic understanding of DNS let’s understand how DNS lookups work.

  • Internet Protocol address (IP address) is the unique address of a device on a network. Computers use these addresses to find and “communicate” with each other. So study different sources to understand IPv4 and IPv6 and learn how to secure your computer.
  • The domain is a text name that people use to remember, identify, and connect to specific Web site servers. For example, a domain such as “facebook.com” is used as an easy way to understand the actual identifier of the target server, i.e., the IP address.
  • The Domain Name System (DNS) translates a domain into the corresponding IP address. Domain Name System (DNS) servers are a collection of four types of servers that make up the DNS lookup process. These include resolving name servers, root name servers, top-level domain (TLD) name servers, and authoritative name servers. For simplicity, we detail only the resolver server.
  • A resolver name server (or recursive resolver) is a translation component of the DNS lookup process that resides on your operating system. It is designed to query – that is, request – several web servers for the target IP address of a domain name.
Algorithm and work of DNS Lookup
Algorithm and work of DNS Lookup

How Does DNS Lookup Work?

The process of finding a site by domain name works as follows:

  1. Your web browser tries to recall the IP address associated with the domain name. If this site has been visited, the IP address may be stored in the local memory cache and recalled from there.
  2. The process continues until one of the components finds out where the destination IP address is.
  3. The browser requests a resolving name server to retrieve the IP address. This request searches through the chain of servers to find the appropriate IP address for the domain.
  4. Eventually, the resolver finds and relays the IP address to the server, which forwards it back to the web browser.

The DNS lookup process is an integral part used throughout the Internet. Unfortunately, criminals can take advantage of vulnerabilities in DNS, so you need to be aware of possible redirects. First, let’s clarify what DNS spoofing is and how it works.

DNS Cache Poisoning and Spoofing Works
DNS Cache Poisoning and Spoofing Works

How DNS Cache Poisoning and Spoofing Works?

Here are the two most common variants of DNS attacks:

  • DNS spoofing is a threat in which legitimate server assignments are simulated to redirect domain traffic. As a result, the unsuspecting victim ends up on malicious websites. This is the target of various DNS spoofing attack methods.
  • DNS cache poisoning is a method of spoofing DNS on the user side. In this case, your system stores the rogue IP address in the local memory cache, causing DNS to direct the victim to the phishing site, even if the server-side is clean.

Methods of DNS spoofing and Cache Poisoning Attacks

Here are the most common methods of DNS attacks:

  • The “man in the middle” hoax: In this case, an attacker gets between your web browser and your DNS server to poison both. The tool can be used to simultaneously poison the cache on your local device and poison the server on the DNS server. This redirects you to a malicious site hosted on the attacker’s server.
  • Hijacking the DNS server: The culprit directly attacks the server to redirect all the requesting users to a malicious site. Once the rogue DNS record is entered into the DNS server, any IP request for the fake domain will lead to the fake website.
  • DNS cache poisoning spam: DNS cache poisoning code is often found in spam email URLs. These emails try to trick users into going to the provided URL, which will infect their computer. Banner ads and images that appear everywhere, in emails and on trustworthy websites – can also direct users to this code. Once poisoned, your laptop will redirect you to fake websites that look like the real thing. This is where the real threats hit your devices.

Risks of DNS Poisoning and Spoofing

DNS spoofing has some risks, which can put your devices and data at risk. Listed below are the risks of poisoning and DNS spoofing:

  • Theft of sensitive data
  • Infecting the device with malware
  • Stopping security updates
  • Censorship
  1. Personal data theft can be incredibly lucrative for attackers using DNS spoofing. Banking websites and famous online stores are easy to spoof, meaning any password, credit card information, or personal information can be compromised. Redirects will be to phishing websites designed to collect your data.
  2. Malware infection is another common threat of DNS spoofing. The destination may turn out to be a fake site containing viruses. Drive-by Downloads are an easy way to automate infection of your system. As a result, if you do not use protection, you are exposed to risks such as spyware, keyloggers, or worms.
  3. A fake DNS can cause your security updates to stop. If fake sites include Internet security vendors, legitimate security updates will not be performed. As a result, the device may be exposed to additional threats such as viruses or Trojans.
  4. Censorship is a risk that is common in some countries. For example, China uses DNS modifications to ensure that all Websites viewed in the country are filtered. This national-level block, known as the Great Firewall, is one example of how powerful DNS spoofing can be.
  5. It’s pretty difficult to eliminate the effects of DNS cache poisoning. Because clearing an infected server doesn’t get rid of the problem on a desktop or mobile device, the device will return to the spoofed site again. In addition, clean devices connecting to the infected server will be compromised again.

How to Prevent?

When trying to prevent DNS spoofing, user-side protections are limited. Website owners and server providers have slightly more options to protect themselves and their users. To properly secure everyone, both sides must try to avoid fakes. To prevent attacks, website owners and DNS providers need to have:

  1. Tools to detect DNS spoofing
  2. End-to-end encryption
  3. Domain name system security extensions

End users, on the other hand, must follow basic rules:

  1. Never click on a link that you do not know
  2. Scan your computer regularly for malware
  3. Clean the DNS cache to solve the poisoning problem
  4. Use a virtual private network (VPN)
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Tips for DNS Server Providers and Website Owners

Protecting users lies entirely with the website owners or DNS server provider. Owners need to use various security tools and protocols to protect against threats. Among these resources are:

  • DNS spoofing detection tools: As the equivalent of end-user protection products, these detection tools actively scan all received data before it is sent.
  • Security extensions (DNSSEC): Essentially a “tried-and-true” DNS label, DNSSEC helps protect against spoofing in DNS lookups.
  • End-to-end encryption: Encrypted data sent for DNS queries and responses protects against cybercriminals, as they cannot duplicate the unique security certificate for a legitimate website.
📌From the latest news in cybersecurity: Last weekend, hackers successfully attacked and corrupted the website of the Ministry of Construction, Housing and Communal Services of Russia.

Working Tips for Users

Users are especially vulnerable, so to avoid becoming a victim of a DNS poisoning attack, it’s essential to follow these simple tips:

  • Never follow a link that you do not know. This applies to emails, text messages, or social media links. Tools that shorten URLs can mask link destinations, so avoid them as much as possible. To be incredibly safe, always choose to type the URL into the address bar manually. But do this only after making sure the link is official and legitimate.
  • Regularly scan your pc for malware. Although you’re unlikely to detect DNS cache poisoning, your security software will help detect and remove any secondary infections. In addition, since fake sites can spread any malware, you should always scan for viruses, spyware, and other hidden problems.
  • If necessary, clean the DNS cache to eliminate the poisoning. Cache poisoning stays on your system for a long time if you don’t clean up the infected data. To do this, check the guide on clearing the DNS cache for your specific device.
  • Use a virtual private network (VPN). This service will create a tunnel for your web traffic and use private DNS servers that use end-to-end encrypted requests. This way, you get servers more resistant to DNS spoofing and requests that cannot be interrupted.

By Stephanie Adlam

I write about how to make your Internet browsing comfortable and safe. The modern digital world is worth being a part of, and I want to show you how to do it properly.

View all of Stephanie Adlam's posts.

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