Types of DNS Attacks: How They Work & How to Stay Protected

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DNS attacks can cause data breaches, phishing, and downtime. Learn about common DNS attack types and how to protect your domain from cyber threats.

by Milena Baghdasaryan

Last Updated:
6 min read
Types of DNS Attacks: How They Work & How to Stay Protected
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The Domain Name System (DNS) lets users and websites interact smoothly and seamlessly by turning human-readable domain names into machine-readable IP addresses. Given the high importance of DNS in digital communications, it often falls victim to attacks, which lead to data breaches, and service outages.

In 2022, 88% of organizations worldwide fell victim to DNS attacks; each incident cost $942,0001 on average. As businesses increasingly rely on digital platforms, understanding and mitigating DNS vulnerabilities has become crucial for maintaining network security and protecting sensitive data.

Key takeaways 

  • A DNS attack aims to target the stability or functionality of the Domain Name System service of a network.
  • Some common DNS attack types include DNS Spoofing (Cache Poisoning), DNS Hijacking, DNS Tunneling, DNS Amplification Attacks, Subdomain Takeover, NXDOMAIN Attacks, and Man-in-the-Middle (MITM) DNS Attacks.
  • The impact of a DNS attack may be devastating, including financial, reputational, and security-related consequences. 
  • There are numerous actions you can take to prevent or mitigate DNS attacks, ranging from implementing DNSSEC and using secure DNS resolvers to regularly monitoring and updating your DNS configurations.

What is a DNS Attack?

A DNS attack refers to attacks that aim to target the stability or functionality of the Domain Name System service of a given network. The wider objective, however, is to redirect users to suspicious, often harmful websites or obtain unauthorized access to sensitive information. 

Common Types of DNS Attacks

1. DNS Spoofing (Cache Poisoning)

In 2020, a major DNS cache poisoning vulnerability dubbed “SAD DNS” was discovered. It affected millions of devices and required widespread patching. But what exactly is DNS spoofing or cache poisoning? It is a malicious technique that corrupts the DNS resolver’s cache with false information. This deception causes DNS queries to return incorrect responses and misdirect users to fraudulent websites. 

When the DNS system is compromised, web traffic is routed to unintended destinations, although the authentic websites retain their true IP addresses.

The vulnerability of DNS caches stems from their inability to independently verify stored data. As a result, erroneous DNS information persists in the cache until either the Time to Live (TTL) expires or manual removal occurs. 

2. DNS Hijacking

Domain Name Server hijacking refers to the type of DNS attack where a hacker intentionally tampers and manipulates how DNS queries are resolved. As a result, users get directed to malicious websites. Attackers choose one of the many methods, such as installing malware on user PCs, seizing control of routers, or intercepting DNS connections to successfully conduct the attack.

Attackers also use DNS hijacking for phishing or pharming purposes. After hijacking the initial, legitimate website’s DNS, they direct users to a similar-looking but fake website where the victims are prompted to enter login credentials. Some governments or governmental agencies that practice censorship over their population make use of DNS hijacking to reroute citizens to state-approved sites.

3. DNS Tunneling

DNS tunneling exploits the DNS protocol to transmit non-DNS traffic over port 53, often bypassing firewalls and security measures. This technique can be used for data exfiltration or command and control communications. Research shows that 46% of organizations have experienced DNS tunneling attacks.

4. DNS Amplification Attacks

DNS amplification is a Distributed Denial of Service (DDoS) attack that aims to manipulate the way the internet’s phonebook operates. It converts a standard DNS query into a deluge of unwelcomed and unwanted traffic. In these attacks, hackers exploit open DNS resolvers to amplify the volume of attack, which overwhelms and disturbs the target systems. The hacker sends small, compact queries through the victim’s falsified IP address, appearing as the intended victim. This prompts the server to dispatch a large response to the target, which is exactly why this type of attack is called “amplification.” 

5. Subdomain Takeover

A 2021 study found that 15% of the top 50,000 Alexa domains were vulnerable to subdomain takeover. A subdomain takeover refers to an attack where the hacker gains control over a target domain’s subdomain. This mainly occurs when the subdomain has a canonical name (CNAME) in the Domain Name System (DNS), but no content is being provided by the host, either because the latter hasn’t been published yet or because it has been removed from the system. In any of the two cases, the hacker can gain access to the subdomain through its own virtual host and then start to host malicious content for it.

6. NXDOMAIN Attack

The DNS NXDOMAIN is a type of flood attack that tries to make servers vanish from the web by overwhelming (or flooding) the DNS server with invalid or fictitious record requests. Since the DNS server wastes time looking for nonexistent records, it loses the necessary time and ability to search for actual, legitimate records. 

As a result, the cache on the DNS server gets overwhelmed by illegitimate, fake requests, and clients can no longer access or find the servers and the roadmap they are searching for. 

7. Man-in-the-Middle (MITM) DNS Attacks

A Man-in-the-middle (MitM) attack refers to the type of cyberattack where criminals exploit weak web-based protocols and get involved between entities in a digital communication channel to gain access to important sensitive or financial data. Since 2021, MITM-compromised emails have increased by over 35%.

Impact of DNS Attacks

Business and Financial Consequences

In 2019, financial services organizations spent an average of $1,304,790 to restore services after each DNS attack, which was a 40% increase from the previous year. The average cost per attack now exceeds $1 million.

Reputational Damage 

Beyond the immediate financial impact, DNS attacks can also lead to significant reputational damage, erode customer trust, and result in long-term business losses.

Increased Phishing and Malware threats

DNS attacks also facilitate other cyber threats. For instance, successful DNS hijacking can dramatically increase the effectiveness of phishing campaigns.

How to Protect Against DNS Attacks

Exploited DNS vulnerabilities can lead to major consequences (e.g. infections related to the malware, data breaches, disruptions of service, and monetary losses). Hackers exploit DNS servers to guide users to dangerous, harmful websites, steal sensitive data, or make some crucial services unavailable or dysfunctional.

Some important steps you can take to prevent DNS attacks are as follows: 

Implementing DNSSEC (Domain Name System Security Extensions)

Use DNSSEC to authenticate and validate DNS responses cryptographically. DNSSEC (Domain Name System Security Extensions) refers to the security extension that helps ensure you are redirected to the correct, legitimate website when you enter a web address in your browser, thereby keeping you away from fake, illegitimate, and potentially malicious websites. Additionally, it helps protect you from DNS poisoning, spoofing, and other forms of unauthorized use. It encompasses a suite of extensions that add cryptographic signatures to your current DNS records. 

You can quickly and effectively verify whether or not your DNSSEC is enabled with the help of PowerDMARC’s DNSSEC checker tool. It will provide you with an accurate and reliable status of your DNSSEC implementation, without the risk of manual errors. 

Using Secure DNS Resolvers

Configuring DNS resolvers helps offer security solutions for those browsing the web (also known as end users). DNS resolvers may include a rich set of functionalities covering smart content filtering, which in turn can help block websites that often spread spam and viruses, and are involved in other forms of cyber attacks. Some DNS resolvers may also provide botnet protection to stop you from communicating with potentially malicious botnets.

Regularly Monitoring and Updating DNS Configurations.

PowerDMARC’s DNS Timeline feature provides a comprehensive yet granular overview of your DNS records including: 

  • DMARC, SPF, and DKIM DNS records
  • BIMI, MTA-STS, and TLS-RPT records
  • MX, A, AAAA, PTR, FcrDNS, NS, TXT, CNAME records, etc. 

The tool captures each change in an easy-to-understand format, offering relevant timestamps for comprehensive monitoring.

The DNS Timeline feature also shows old and new records side by side for comparison. The system allows you to filter DNS changes based on types of records (SPF or DMARC), domains or subdomains, time ranges, and other key distinguishing factors. The Security Score History tab provides an easy-to-grasp visual representation of the security rating of your domain, tracking any changes that occur over time. 

Deploying Anti-DDoS Solutions

Anti-DDoS solutions may include on-premises anti-DDoS hardware, cloud-based anti-DDoS services, NTAs (i.e. Network Traffic Analyzers), antivirus software, and web application firewalls. They serve to detect and mitigate DDoS attacks, thereby protecting your system from malicious actors. 

Strengthening Email Security with Email Authentication

Email authentication protocols protect your emails from various types of unauthorized use, including phishing, spam, and spoofing attacks. They can indirectly contribute to mitigating certain DNS-based attacks. Here’s how:

  • Attackers often use spoofed domains in phishing attacks. DMARC enforces authentication, reducing the risk of attackers using your domain in malicious emails.
  • By ensuring that only legitimate sources can send emails using your domain, email authentication reduces the likelihood of attackers injecting malicious DNS records for phishing campaigns.
  • They work alongside DNS-based security measures like DNSSEC, which protects against DNS tampering and hijacking.
  • Protocols like MTA-STS and DANE use DNS to enforce secure email transport via TLS, protecting against Man-in-the-Middle (MitM) attacks.

Additional Recommendations

  • Utilize a comprehensive patch management process for DNS software.
  • Restrict access and sophisticate DNS server configurations.
  • Carefully examine and oversee DNS traffic in real time to identify unusual activity and potential attacks before it’s too late.
  • Make regular scans to see the vulnerability level of your DNS infrastructure.

Final Words

DNS attacks may immediately provoke fear and panic as they can jeopardize the stability and security of a given system. The scope of impact, covering financial, reputational, and safety aspects, might also be quite alarming for various companies. However, it is important to not get overwhelmed when under attack, and instead implement measures and mechanisms that can prevent and mitigate it.

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