How to Fight Against DNS Data Exfiltration?

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DNS Data Exfiltration

For cybercriminals, getting sensitive data from an organization is a goldmine. No matter how big or small the data is, they can easily sell it on the dark web. This is the reason why cybercriminals are actively finding ways to collect data from companies without them knowing. And one of the ways they do this is through DNS data exfiltration. The best way to combat DNS data exfiltration is by using DNS filtering.

DNS Filtering: What Is DNS?

DNS, or Domain Name System, is the protocol the internet uses to find websites. Without the DNS, internet users will have to find websites using IP addresses all the time and the internet becomes inconvenient to use.
DNS works when you input the name of a webpage on your browser. The DNS takes that webpage name and searches for the IP address on the internet so that your device can connect to the webpage you are looking for. There are billions of DNS queries daily and it plays a huge part in how the internet works.

DNS Filtering: What Is DNS Data Exfiltration?

DNS data exfiltration is a hacking method that is common to professional hackers who want to steal data. This hacking method takes advantage of the fact that DNS traffic is not usually monitored by many cybersecurity tools and solutions.

The first step of DNS exfiltration is to infect a target pc with malware. The malware will scan the system for valuable data and utilize DNS packets to send that data out. Though DNS packets only carry DNS queries, it can be cracked to send out any kind of data.

Once the cracked DNS packet is released from the network, it travels to the hacker’s registered domain name. Once the data has been transferred to the hacker’s domain, they can open and view the stolen data. Then the Data exfiltration is complete.

DNS Filtering: What Data Can DNS Data Exfiltration Take?

DNS data exfiltration is a dangerous hacking method because it can exfiltrate almost any data, no matter how big. To send large files, the malware breaks the data down into chunks and sends it to the DNS traffic. On the other end, the data is being reconstructed by the hacker’s DNS server as it receives the data packets. Once the process is finished, the hackers will have a duplicate copy of the data.

Though DNS data exfiltration can transfer all kinds of data, these data types are the most common targets of DNS data exfiltration:

  • Credit card information – Cybercriminals can do a lot of things with credit card information. If they have your full credit card details, they can use it to make unauthorized purchases or sell it on the dark web.
    Credit card information saved as a document file in an infected computer can easily be broken down into DNS packets and sent over to hackers.
  • Customer personal information – Personal information is another highly valuable information for hackers. Personal information like name, address, email, and telephone number can easily be used to commit fraudulent acts or to steal an identity.
  • Customer Medical information – Medical information is considered as highly-sensitive data. Not only does it contain personal information, but it also contains medical history and current ailments that can be used to impersonate a person.
    If your medical records are stolen, cybercriminals can use it for financial gain by selling it online or using it for personal use and use it to obtain healthcare services under your insurance.

How Does DNS Filtering Help Prevent DNS Data Exfiltration?

DNS filtering is one of the ways you can prevent DNS Data exfiltration. DNS filtering is a system that restricts users from connecting to unknown IP addresses. By using DNS filtering, an infected computer can’t send information back to the hacker’s DNS server, making the malware useless.
DNS filtering software can protect a company’s network by blocking known phishing and malicious sites, C&C callback events, and malware domains. Advanced DNS filtering software, like Comodo’s Cdome, can stop malicious domain requests and IP responses and do threat analysis to discover the nature of the cyberattack.


Sensitive data is a valuable commodity for cybercriminals, and they will do everything they can to get data from companies and internet users. By using DNS filtering, users can prevent DNS data exfiltration and protect their data from spyware attacks. Visit today to know more about DNS filtering.

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