DNS Attacks: How Cybercriminals Redirect Your Web Traffic

Every time you type a website address into your browser, something invisible happens first. Your computer asks a system called DNS, the Domain Name System, to translate that human-readable address into a numerical IP address that computers understand. It is the internet's phone book, and it works so seamlessly that most people never think about it. But cybercriminals think about it a lot, because compromising DNS gives them the power to redirect your web traffic wherever they want, without you noticing a thing.

flowchart LR
    A["DNS Query Sent"] --> B["Attacker Intercepts"]
    B --> C["Spoofed DNS Response"]
    C --> D["Victim Redirected"]
    D --> E["Fake Website Loaded"]
    E --> F["Credentials Stolen"]
  

For small businesses, DNS attacks represent a particularly insidious threat. They can redirect your employees to fake login pages, intercept sensitive communications, and even take your business website offline. Understanding how DNS attacks work is the first step toward defending against them.

How DNS Works (The Simple Version)

Before diving into attacks, here is a quick primer on how DNS functions in everyday business use:

1. You type a website address like "yourbank.com" into your browser.
2. Your computer asks a DNS server (usually provided by your internet service provider) to look up the IP address associated with that domain name.
3. The DNS server responds with the correct IP address, such as 192.168.1.100.
4. Your browser connects to that IP address and loads the website.

This process happens in milliseconds, dozens or hundreds of times per day, for every device on your network. And because it is so fundamental and so trusted, it presents an attractive target for attackers.

Types of DNS Attacks

Cybercriminals exploit DNS in several ways, each with different methods and consequences:

DNS spoofing (cache poisoning)

The attacker corrupts the DNS cache on a server or device, replacing the legitimate IP address for a domain with a malicious one. When your employee types in the address of your company's banking portal, the corrupted DNS sends them to a fake version of the site that looks identical but captures their login credentials. This technique is closely related to man-in-the-middle attacks.

DNS hijacking

The attacker gains access to your DNS settings, either through your domain registrar, your router, or your DNS provider, and changes them to point to servers they control. This can redirect all traffic intended for your business website to a fake site, intercept emails, or display fraudulent content to your customers.

DNS tunneling

Attackers use DNS queries to smuggle data out of your network. Because DNS traffic is rarely inspected by firewalls, it provides a covert channel for exfiltrating stolen data. The stolen information is encoded into DNS requests that appear normal to casual inspection but contain hidden payloads.

DNS amplification attacks (DDoS)

Attackers send small DNS queries with a forged source address (your company's IP) to open DNS servers. These servers send back much larger responses to your IP address, overwhelming your network with traffic and potentially taking your business offline. This is a type of distributed denial-of-service attack.

Domain hijacking

Attackers gain control of your domain name itself by compromising your domain registrar account. They can then redirect your website, intercept your email, and effectively impersonate your business online. For a small business, losing control of your domain can be catastrophic.

Why DNS Attacks Are Dangerous for Small Businesses

DNS attacks pose unique risks because they exploit trust at a fundamental level:

• Invisible redirection: When DNS is compromised, your employees visit fake websites without any visible warning. The address bar shows the correct domain name because the attack happens at the translation layer, below what the user can see.
• Broad impact: A single DNS compromise can affect every device on your network simultaneously. If your office router's DNS settings are changed, every computer, phone, and tablet connecting through it is affected.
• Credential harvesting at scale: A DNS spoofing attack that redirects your company's email login page to a fake version can capture every employee's credentials as they try to log in throughout the day.
• Customer-facing damage: If attackers hijack your domain, your customers see a fake website or receive emails from attackers pretending to be your company. The reputational damage can outlast the technical incident.
• Difficult to detect: Because DNS operates in the background, many businesses do not monitor it. Attacks can persist for days or weeks before anyone notices something is wrong.

DNS is often called the internet's phone book, but imagine if someone could secretly change the numbers in that phone book. Every call you think you are making to your bank actually goes to a criminal. That is what a DNS attack does to your web traffic.

Signs of a DNS Attack

Watch for these warning signs that could indicate DNS compromise:

• Unexpected website redirects: Employees being sent to unfamiliar websites when trying to access familiar services.
• Certificate warnings: Browser warnings about invalid or untrusted certificates on websites that normally load without issues.
• Slow DNS resolution: Websites taking noticeably longer to load, or DNS lookups timing out intermittently.
• Unusual network traffic: Large volumes of DNS traffic or connections to unfamiliar DNS servers in your network logs.
• Customer reports: Clients telling you that your website looks different, asked for unusual information, or displayed suspicious content.
• Email delivery issues: Emails not arriving at their intended destinations because DNS records have been altered to redirect email traffic.

How to Protect Your Business from DNS Attacks

Defending against DNS attacks requires attention at multiple levels:

1. Use a reputable DNS provider

Switch from your ISP's default DNS to a security-focused provider like Cloudflare (1.1.1.1), Google Public DNS (8.8.8.8), or Quad9 (9.9.9.9). These providers implement DNSSEC validation, malware blocking, and other protections that ISP DNS servers often lack.

2. Enable DNSSEC

DNS Security Extensions (DNSSEC) add a layer of authentication to DNS responses, ensuring that the response you receive actually came from the legitimate DNS server and has not been tampered with. If your domain registrar supports DNSSEC, enable it for your business domain.

3. Secure your domain registrar account

Your domain registrar is the administrative gateway to your DNS settings. Protect it with a strong, unique password and multi-factor authentication. Enable registrar lock to prevent unauthorized transfers of your domain name. Review authorized contacts regularly.

4. Secure your router

Change default router credentials. Update firmware regularly. Disable remote management if you do not need it. Verify that your router's DNS settings point to your intended DNS provider and have not been changed. For more, see our safe browsing habits guide.

5. Implement DNS filtering

DNS filtering services block access to known malicious domains at the DNS level, preventing employees from reaching phishing sites, malware distribution servers, and command-and-control infrastructure, even if they click a malicious link.

6. Monitor DNS traffic

If you have the capability, monitor your DNS traffic for anomalies. Unusual volumes of DNS requests, queries to uncommon domains, or DNS traffic on non-standard ports can all indicate DNS tunneling or other attacks.

7. Use encrypted DNS

DNS over HTTPS (DoH) or DNS over TLS (DoT) encrypts DNS queries, preventing attackers from intercepting or manipulating them in transit. Most modern browsers and operating systems support encrypted DNS.

Protecting Your Business Domain

Your domain name is one of your most valuable digital assets. Here is how to protect it:

• Enable registrar lock: This prevents unauthorized changes to your domain settings, including DNS records and domain transfers.
• Use a dedicated email for your registrar account: Do not use your main business email. A separate, secure email account for domain management reduces the risk of social engineering attacks.
• Enable MFA on your registrar account: Multi-factor authentication prevents attackers from accessing your domain settings even if they obtain your password.
• Keep registration information current: Ensure your contact information is up to date so you receive important notifications about your domain, including expiration warnings and unauthorized change alerts.
• Set up auto-renewal: An expired domain can be registered by anyone, including attackers. Auto-renewal prevents accidental lapses.

Losing control of your domain name is one of the most devastating things that can happen to a small business online. It takes minutes for an attacker to redirect your website and email, but it can take weeks to regain control.

Action Steps for Your Business

Protect your business from DNS attacks with these immediate steps:

1. Switch to a secure DNS provider like Cloudflare, Google, or Quad9 on your office router and all company devices.
2. Secure your domain registrar account with a strong password, MFA, and registrar lock.
3. Update your router firmware and change any default credentials.
4. Enable DNSSEC for your business domain through your registrar.
5. Consider DNS filtering as a low-cost security layer that blocks malicious domains for your entire network.
6. Train your employees to recognize certificate warnings and unusual website behavior that could indicate DNS compromise.

DNS attacks exploit something we all take for granted: that when we type a web address, we end up where we intended. By securing your DNS infrastructure, protecting your domain, and training your team to spot the warning signs, you can ensure that your business's internet traffic goes where it should, not where an attacker wants it to go.