What is Passive DNS? How Does Passive DNS Work

The Domain Name System (DNS) data is stored in Passive DNS. Security analysts and researchers can utilise DNS data to find occurrences and incidents that are relevant to their inquiry to map out rogue networks.

It is possible to think about passive DNS as a database of all the domains the IP addresses you’re interested in have previously resolved to. As a result, it’s like a diary in which you may read about the life of the person who had it.

There is a popular abbreviation for “pDNS,” which stands for “passive DNS.” It was originally developed to aid with cybersecurity. Before its creation in 2005, all DNS records indicating which domains refer to certain IP addresses would be deleted after a given period. To get around this, Florian Weimer created passive DNS. Your curiosity has been piqued. Find out more by reading on.

Do you know how to use Passive DNS?

When you enter a domain name into your browser’s address bar, your request is sent to a DNS server, where it is processed. You’re probably aware that a domain name like google[.]com isn’t understandable to computers because they only comprehend numerical data. This is how it works: a DNS server takes a domain name like google.com and converts it to an IP address. There are several Google’s IP addresses that might be used, including 8[.]8[.]8[.]8.

Read More: What is an Application Gateway?

You should also be aware that a single IP address might be used by several domains. According to folklore, the two of them share the same host. 8[.]8[.]8[.]8 is the IP address. A passive DNS query on this web service found that the domain 8 also resolves to 0–9[.]ru, 1-189tais[.]com, and 2t2t[.]top, aside from google[.com]. This is an example of passive DNS in action.

Since 4 January 2019, 0–9[.]ru users have been sent to a page with the URL 8[.]8[.]8[.]8, which was last resolved on 14 May 2021. In this scenario, let us say you are a security researcher or analyst looking for evidence of suspicious activity at the IP address. It’s possible to see if any of the domains linked to it are malicious by doing a domain search (if it appears on a popular blocklisting site or malicious Uniform Resource Locator [URL] database).

Why Is Passive DNS Helpful in Cybersecurity?

Passive DNS data may be used in a plethora of ways to identify cyber threats and learn more about an attack. Here are a few examples:

Make a List of Your Attacks

Malicious campaigns frequently make use of a large number of domains and IP addresses to maximise their financial gain. There is a direct correlation between the number of harmful websites that may be planted with malware and the number of victims that can be lured to them.

There are a few ways passive DNS data can assist you to find at least one domain that should be avoided by you or your company’s users. Given a single domain, the same is true. A passive DNS database or application can assist you to track down all the IP addresses it has resolved over time. Your attack profile is made up of the links you discover.

Find Out About Other Malicious Web Properties!

There may not be an exhaustive list of recent cyberattacks in the press or on cybersecurity blogs, but these sources can provide a lot of knowledge nonetheless. Doing extensive research on your own may be necessary to ensure the highest level of protection against hazards.

Additionally, you may use passive DNS data to build published lists of indications of compromise or websites to avoid to prevent being the next victim of an attack.