Defense against DNS Tunneling

DNS tunneling is a malware technique that allows an attacker to establish a command-and-control (C2) channel to a victim’s computer. This backdoor allows attackers to perform different types of nefarious activities like data theft and malware installation on the victim’s computer.

Need to protect your organization against DNS tunneling? Filter your DNS requests for better security with DNSFilter.

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What is DNS Tunneling and how can it be detected?

DNS tunneling is a strategy used by black hats to create a covert channel into a victim’s computer or organization’s network.

The channel created provides a means of encapsulating a malicious payload within DNS queries to take advantage of the relatively unrestricted flow of DNS traffic—especially in scenarios where almost all other traffic is restricted.

DNS tunneling can be detected by performing DNS query analysis or traffic analysis, for example, analyzing the frequency of DNS traffic against a normal traffic benchmark within the network. When anomalies in query count and frequency are detected, a DNS tunneling attack is most likely in effect.

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70% of all cyber attacks involve the DNS layer

What is DNS Tunneling used for?

The covert channel created by a DNS tunnel is similar to a criminal breaking into a house: The potential damage they can cause is only limited by their imagination.

A common use of DNS tunneling is data exfiltration, a process in which attackers steal information from the victim’s computer. Another use of DNS tunneling is to establish remote access to a victim’s computer or network allowing the attacker to execute malicious commands or install malware.

DNS tunneling can also be used in releasing a worm into an organization’s network. This worm can be used to introduce ransomware or to shut down an organization’s business activities.

How to stop DNS Tunneling

Having a DNS security platform to filter your DNS requests is one battle-tested solution that can help prevent DNS tunneling attacks.

Because DNS tunneling uses DNS queries to establish a malicious connection with the attacker’s computer, monitoring, detecting, and blocking malicious queries proves to be very effective in combating these types of attacks.

DNSFilter uses the following strategies to detect and block DNS tunneling attacks:

  • Detect phishing attacks that can lead to the installation of malware
  • Each time a DNS server receives a DNS request, it is compared against a block list of known malicious domains
  • Detection of Domain Generation Algorithms (DGAs) used by attackers to generate random domains for attacks
  • Detect unusual DNS traffic patterns

And of course, you should run regular system updates to ensure you have no newly detected vulnerabilities.

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Threats We Block

malware threat icon

Malware is short for “malicious software” and can be spread in a variety of ways such as forced downloads or malicious ad content. It includes viruses, worms, spyware, ransomware, and trojan horses. The most common way that malware gets onto a computer or other device is through surfing hacked sites. So the best way to protect your company from malware is to prevent your users from ever accessing these sites.

Zero Day Threats

DNSFilter is the best security product to protect against zero-day attacks because our proprietary AI tools are constantly scanning the internet for new sites that could potentially contain scams or malware. DNSFilter detects threats up to 80 hours faster than static threat feeds.

Phishing Attacks

Phishing and spear phishing attacks are a favorite among hackers because they are relatively easy to implement. They use email or chat (such as public Slack channels or Discord) to lure victims into a scam, or more commonly to a link where they will enter data or download malware. Phishing attacks can be broad and general, impersonating institutions like banks or hospitals, or they can be targeted and sophisticated, often impersonating employees inside your own organization. Because DNSFilter is constantly scanning the web for new malicious sites, we can prevent phishing attacks by stopping your employees before they hit a malicious site, or give a phisher their data.


Ransomware is software that allows hackers to encrypt files, networks, and computers remotely. They then hold your data hostage until your company pays a ransom. With the evolution of ransomware in key sectors like healthcare as well as the ubiquity that Ransomware-As-A-Service offers, this threat technique has become one of the top causes of cybersecurity incidents worldwide. In 2020 the average ransomware demand was $233,000 and they now make up around ⅓ of all security breaches. If your company doesn’t pay you risk data loss, or in some cases, data being sold on the darkweb. The key to ransomware protection is stopping the malware from being downloaded in the first place, which usually requires blocking the site that hosts the malicious content before an unsuspecting user can visit it and become infected.

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A true 21st century threat, cryptojacking is the unauthorized takeover of a computer or network to “mine” cryptocurrency. Because new currency is created by computers using massive amounts of computing resources computational bandwidth is at a premium. Cryptojacking infects a distributed network of computers to utilize their computational bandwidth, slowing down the device and, at scale, driving up your energy costs. DNSFilter has a robust catalog of known cryptojacking sites, and domains that contain cryptocurrency references can be blocked in a single click.


Thousands of people type into their browser every day. Turns out, the average internet user isn’t always the best speller. Bad actors take advantage of this by setting up malicious sites with domain names that feature common misspellings of familiar sites. Everyday we seem to discover new “Chase” login pages with an increasingly creative variety of typos (check out the fake sites here). DNSFilter protects the user from typosquatting by blocking access to domains that are known to contain malware or malicious content. Never worry about misspelled domain names again.

Man-in-the-Middle attacks

Have you ever visited a site that just looked off? Middleman attacks create a fake site that mimics a trustworthy brand login, and provides form fields where users enter their password, username, and potentially credit card data. The hacker then absconds with this data, leaving the user confused and exposed. Our AI-tool scans the UX of domains and includes logo matching, identifying when logos are being used on sites where they do not belong, ensuring that man-in-the-middle sites are quickly found, cataloged, and blocked.

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