The Domain Name Server (DNS) is an essential part of the internet. It’s similar to a large phonebook which your computer uses to record hostnames to IP addresses to interact with public services like websites.
DNS server configurations which lack proper security settings can often lead to DNS vulnerabilities and can also pose serious problems. Like for instance, attackers can exploit the system to perform things like transferring DNS zones, redirect web and email traffic, or even carry out dangerous DNS amplifying attacks.
When such things happen so, the website users don’t have a way to identify either their traffic has been sent to another server, or that their emails were sent to some other servers rather than the original server from the targeted domain. Thus, for this reason, it is imperative to keep your DNS server protected and secured from vulnerabilities.
Today, let’s look at different ways by which we can combat DNS vulnerabilities. But before that first have a look at the fundamental DNS weakness and vulnerabilities.
DNS Weakness and Vulnerabilities:
Fundamentally, there are three significant vulnerabilities associated with DNS. The attackers can use these vulnerabilities to exploit or abuse DNS:
- The internal DNS servers have all the IP addresses and server names for their domains and share it with anyone who asks. Such an act makes DNS a great source of information for attackers when they are attempting to do an internal investigation.
- The DNS caches can be manipulated as they aren’t authoritative. Let’s suppose if your DNS server is full of bad records so, the computer can become a fool and can get into wrong places.
- DNS spreads query information from internal servers to the outside ones. The attackers learned how to use this behavior to create covert channels to ex-filtrate data.
Six Ways to Prevent DNS Vulnerabilities:
You may now have a clear idea about DNS vulnerabilities and how they can exploit a user. In today’s modern age, where cybersecurity is the dire need of every user, it is imperative to do something against these vulnerabilities.
An individual, a regular internet user, or any business can prevent the DNS leaks or other such related vulnerabilities by DNS leak test. They can also alter their device setting to another DNS server. But there should be some different ways to combat these vulnerabilities.
Following are the six best ways by which you can combat DNS vulnerabilities:
- Audit DNS Zones
- Update your DNS servers regularly
- Restrict your zone transfer
- Start using separate DNS servers
- Use anti-DDOS services
- Two-factor authentication
Now, let’s discuss each of the above-mentioned preventive ways in detail:
1. Audit DNS Zones:
The first and the most important thing you need after reviewing the DNS main server configuration is your DNS zone.
Most of the time, we forget about testing domains, subdomains which sometimes run outdated software or even unrestricted areas vulnerable to attack.
To audit your DNS zone, all you need is to explore all your public DNS records by using the best network security tools. Next, review all your zones, IPs, records, and then audit it.
2. Update Your DNS Servers Regularly:
When you run your name servers so, you can configure, test, and try certain things which you might not be able to perform on private DNS servers. Such as the ones your hosting provider gives you or else when you sign up for Cloudflare.
When you choose to run your DNS servers so, you most likely to use software like BIND, Microsoft DNS, NSD, and PowerDNS. Along with the rest of the operating system, it is essential to keep the other software updated to prevent service exploitation, which targets bugs and vulnerabilities.
The most recent versions of all popularly known DNS servers include patches against the known vulnerabilities, along with support for security technologies such as DNSSec and RRL which are beneficial in preventing DNS attacks.
3. Restrict Your Zone Transfers:
Restricting your zone transfer is one of the best possible ways by which you can protect your DNS zone information.
A DNS zone transfer is a replica of the DNS zone. It is a technique in which slave name servers often use to enquire master DNS servers. At times, attackers can attempt to carry out DNS zone transfer to have a better understanding of your network.
To avoid any such thing to take place, all you need is to restrict the DNS servers which are allowed to perform a zone transfer. Also, you can limit the approved IP addresses which make such requests.
4. Start Using Separate DNS Servers:
Using an isolated DNS server is also helpful in combating DNS vulnerabilities. When you have DNS server isolated from other servers so, there will be fewer chances of getting attacked by web application attackers.
You can run your DNS server by using a dedicated server or cloud where you can host the web services such as application server, database server, and HTTP server.
It is a common practice among small cooperation who often keep their server services in one lone cPanel or Plesk box.
If you think to do so, then you must make sure that the box has a robust server hardening for each daemon as well as for the applications which are running inside the operating system.
Although the best thing you can do is to use your own dedicated DNS server, it won’t be a matter if it is based on dedicated servers or Cloud server. The only important thing is it should be 100% dedicated to DNS services.
By closing unnecessary server ports, filtering your traffic by using a firewall, stopping unwanted OS services, and allowing essential services like SSH and DNS servers, you can reduce the chances of a DNS attack.
5. Start Using Anti-DDOS Services:
Another impressive way by which you can combat DNS vulnerabilities is to start using anti-DDOS services.
The small and midsize DOS and DDOS attacks can alleviate by changing the HTTP services, kernel response, and network filters from the operating system. While when a big DDOS chases you so, there are few data centers which can help their users by providing a real anti-DDOS service.
It should be essential to note that if you run your DNS servers so, you will be under massive DDOS attacks. Your usage in terms of bandwidth or packets per second will most likely cause you big trouble, in case your ISP provide you a null route to your IP address.
Hence, the best thing you can do is to hire an anti-DDOS service such as Akamai, Cloudflare, Incapsula to mitigate DDOS attacks and to keep your DNS servers secure and counteracting at all times.
6. Two-Factor Authentication:
Let’s suppose you are running your DNS servers and you decide to use a third party DNS managed service like Cloudflare DNS. By using such services, you will be assured that their servers are well secured and protected.
But you have no idea that you are not safe. The attacker can get access to your user name and password. However, you can have control on your account if you are using two-factor authentication.
You can set up two-factor authentication protection on your DNS server provider, and if it is possible so, you can also avoid phone calls, SMS verification and use Google Authenticator which is more secure.
To sum up all, attackers and hackers will always be trying to target public and company services to find some vulnerability in your DNS. Having a DNS with hardening policy will surely help you to reduce the attacks and vulnerabilities.
You should audit your DNS zones as mentioned in the first step to secure your DNS servers and try to cut your public DNS information as much as possible.