DNS security: Definition and best practices

What is DNS security?

DNS security refers to the measures used to protect the domain name system (DNS) from threats like spoofing, hijacking, cache poisoning, and large-scale disruptions like DDoS attacks. Since DNS is involved in nearly every online request, it's a natural target and a weak spot if left unprotected. Strong security policies help flag unusual behavior and detect malware, data leaks, or compromised systems. 

Reliable DNS providers implement various security measures, including protocols like DNS over HTTPS (DoH) to encrypt queries and increase user privacy. Security tools like domain name system security extensions (DNSSEC) protect against cyberattacks by assigning unique signatures to data pieces, allowing verification of the data's authenticity. DNS filtering helps filter out harmful websites and blocks malicious ones.

Although trustworthy DNS providers employ advanced security tools to manage DNS-associated risks, hackers sometimes slip through and may still harm your devices or networks. So, DNS servers also need careful monitoring and regular audits to mitigate traffic anomalies and identify threats.

Why is DNS security important?

DNS security is important because the DNS is often the first point of contact between your device and the internet. The IP address of every website is held by an authoritative name server somewhere in the world. To speed connectivity and reduce load on those servers, the DNS also uses recursive DNS servers, or DNS resolvers, which are typically provided by internet service providers (ISPs). When you type a domain name into your browser, your device's local DNS server first contacts a nearby recursive resolver to retrieve the correct IP address.

If attackers manage to exploit vulnerabilities in the DNS process, they can redirect you to fake sites, steal your data, or slip malware onto your device.

Proper DNS security solutions prevent, detect, and block these threats before they cause damage. They typically include:

• Secure DNS servers that block access to known malicious domains
• DNS filtering services to restrict access to phishing or adult content
• DNSSEC to verify that DNS responses haven't been tampered with
• Security tools to monitor and log suspicious DNS activity

So, do you need DNS security? Absolutely. Whether you're protecting personal devices or managing an entire network, ignoring DNS threats leaves a critical gap in your defenses.

How secure DNS works

Secure DNS encrypts your DNS traffic and makes sure the responses you get are real. By default, DNS queries are unencrypted, which means anyone between your device and the DNS server can see or change them.

DNS security changes that in several ways:

• DNS over HTTPS (DoH) encrypts DNS data using HTTPS. It hides your DNS requests from ISPs or anyone watching the network.
• DNS over TLS (DoT) uses a secure TLS connection (the same tech used in banking websites) to encrypt DNS data.
• DNSSEC adds digital signatures to DNS records to confirm that the response hasn't been tampered with.

When you use a secure DNS server that supports these technologies, your device talks to the server over an encrypted connection. You get the right answers from a trusted source, free of tampering or eavesdropping.

How to set up secure DNS on your web browser

Most modern browsers let you enable DNS security in just a few clicks. Follow these steps to set it up on some of the popular ones.

Chrome

1. 1.Go to "Settings"> "Privacy and security"> "Security."
2. 2.Scroll down to "Advanced."
3. 3.Turn on "Use secure DNS."
4. 4.Pick a provider like Cloudflare or Google or enter a custom one.

Firefox

1. 1.Open Settings.
2. 2.Scroll to "Network settings" and click "Settings."
3. 3.Check the box for "Enable DNS over HTTPS."
4. 4.Choose your provider or add a custom one.

Edge

1. 1.Go to "Settings"> "Privacy, search, and services."
2. 2.Under "Security," find "Use secure DNS."
3. 3.Toggle it on and choose a service.

Once set up, your browser will use encrypted DNS connections, adding a strong layer of DNS protection to your browsing.

Types of DNS attacks

Hackers use different methods to exploit DNS server security and access confidential user information. DNS spoofing, tunneling, hijacking, amplification, and NXDOMAIN attacks are the most dangerous DNS attacks that criminals use to disrupt, divert, or manipulate DNS data. A poorly secured recursive DNS server can be a prime target for these attacks.

DNS spoofing

DNS spoofing, or cache poisoning, is when an attacker corrupts the DNS cache to redirect unsuspecting users to fraudulent websites that mimic the user's intended destination. DNS spoofing infects users' computers with malware, which allows the attackers to monitor their internet activity and steal sensitive information. This method of a DNS attack is extremely dangerous. The corrupted DNS data can sit in a user's device for a significant amount of time without being noticed and lead them to malicious websites.

DNS tunneling

Hackers use DNS tunneling to circumvent network limitations by entering false data into DNS queries and responses, allowing them to reroute DNS requests to their servers. In the event of a successful attack, attackers take control of the apps on the device and access sensitive user information.

DNS hijacking

DNS hijacking, DNS redirection, or DNS poisoning is when an attacker redirects DNS queries to malicious websites. Hackers intercept DNS traffic, take over routers, alter DNS settings, or install malware on users' computers.

A related technique is fast flux, where attackers quickly rotate the IP addresses tied to malicious domains, using a network of infected computers. This makes it harder to detect and shut down the attack.

DNS amplification attacks

A DNS amplification attack is a type of DDoS attack that targets DNS infrastructure. Attackers send small DNS queries, tricking DNS servers into responding with much larger replies. The amplified traffic is then sent to the target's network, overwhelming it and causing service outages.

NXDOMAIN attacks

An NXDOMAIN attack, or a DNS water torture attack, floods a DNS server with requests for non-existent records. Such attacks deplete traffic resources, causing denial of service for legitimate requests and compromising normal website or service performance. Hackers usually use automated botnets to perform NXDOMAIN attacks.

What are the best DNS security practices?

Employing the following security best practices may protect your personal or business data from prying eyes and prevent hackers from compromising your devices:

• Use encrypted DNS protocols. Switch to DNS over HTTPS (DoH) or DNS over TLS (DoT). These prevent third parties from snooping on or altering your DNS data.
• Use domain name system security extensions (DNSSEC). DNSSEC protects DNS servers by assigning cryptographic signatures to DNS records. If the DNS request doesn't match the associated signature and comes from a non-authoritative server, DNSSEC will reject it to protect your network from DNS cache poisoning and spoofing.
• Enable DNS filtering. Use a DNS filtering service that blocks access to malicious or inappropriate domains. It's a simple way to reduce risk, especially for businesses or homes with multiple users on the network.
• Monitor DNS traffic and servers. Recursive DNS monitoring services instantly flag and block suspicious traffic before it causes problems.
• Run regular DNS audits. A thorough DNS server audit involves routinely checking DNS settings to identify unusual system behavior or network security loopholes that cybercriminals could exploit. DNS audits can also help you identify outdated records that can be erased, ensuring smooth DNS performance.
• Use a reliable DNS service. Choose a trustworthy and security-oriented DNS provider that supports DNSSEC and has built-in tools against DDoS attacks. Also, managed DNS defends traffic against eavesdropping, tampering, and data trackers while ensuring high availability and performance.
• Secure your DNS infrastructure. Use strong, unique passwords and enable multi-factor authentication (MFA) on any system that manages DNS settings.
• Implement access control lists (ACLs). ACLs help organizations restrict unauthorized users from accessing confidential DNS information and reduce the potential attack surface.
• Enable rate limiting. Rate limiting helps mitigate the risk of DDoS attacks. It restricts requests from a single IP address that surpasses a certain query threshold, making it more difficult for attackers to flood the system.

What are DNS security extensions (DNSSEC)?

DNS security extensions (DNSSEC) is a security protocol that authenticates DNS records by assigning digital signatures to DNS data. 

For a DNS lookup to be secure, every step in the DNS chain has to be signed and verified. If something doesn't check out, the response is rejected. That's how DNSSEC protects against spoofing and cache poisoning.

DNSSEC is especially important for organizations running their own domains or internal DNS systems.

What are other ways to secure DNS?

Beyond DNSSEC and encrypted protocols like DoH or DoT, there are other ways to secure your DNS:

• DNS filtering blocks access to dangerous or inappropriate domains. It's often offered by consumer security suites or enterprise firewalls.
• DNS layer security monitors and filters traffic at the DNS level. It's a proactive way to stop threats before they reach endpoints.
• Redundant DNS servers improve uptime and provide a fallback in case of an attack or outage.
• DNS firewall checks every query against threat intelligence databases. It blocks requests to known malicious domains automatically. 

How NordVPN helps with DNS security

Besides offering a safe and encrypted online experience, NordVPN provides advanced security features for your DNS traffic protection. NordVPN comes with a private DNS feature that shields your online activity, encrypts DNS queries, and offers unwanted traffic filtering.

In addition to the handy private DNS, NordVPN also features DNS leak protection, which prevents your DNS requests from being accidentally exposed to cyber threats due to a bad or faulty configuration.

Because DNS is often referred to as the phone book of the internet, these NordVPN features may be the cornerstone to protecting your DNS traffic from hackers attempting to gain access to your data through phishing, man-in-the-middle attacks, and DNS hijacking.