Scoring 3.0 Severity: Medium
Factor: Network Security
Name in API: service_dns
Decay Period: 45 Days
Summary
It is not inherently risky to expose a DNS server, which translates domain names, such as example.com, into IP addresses that browsers use to find and access web sites. Most network operators aid public web navigation with internet-facing DNS servers. A misconfigured DNS server, however, can be vulnerable to a malicious redirection of web R or a distributed denial of service (DDoS) attack, where an attacker floods a domain’s DNS servers to disrupt DNS resolution for that domain.
What is a DNS Server?
A DNS (Domain Name System) server functions as a crucial component of the internet infrastructure, translating human-readable domain names into machine-readable IP addresses. When a user enters a website's domain name into their web browser, the DNS server retrieves the corresponding IP address associated with that domain from its database and directs the user's request to the appropriate destination. Essentially, it serves as a digital phone book for the internet, efficiently routing traffic across the vast network. DNS servers operate in a hierarchical fashion, with different types such as authoritative DNS servers, which store specific domain information, and recursive DNS servers, which fulfill user requests by querying multiple servers if necessary. They play a fundamental role in ensuring the smooth functioning and accessibility of the internet for users worldwide.
What are the risks involved with exposing DNS Server?
One significant risk is DNS spoofing or cache poisoning, where malicious actors manipulate the DNS records to redirect users to fraudulent websites, leading to phishing attacks, malware downloads, or data theft. DNS servers are susceptible to distributed denial-of-service (DDoS) attacks, which flood the server with overwhelming traffic, causing it to become unresponsive and disrupting internet services. If a DNS server is compromised, it can lead to widespread outages, as it controls the translation of domain names into IP addresses for countless websites. Such incidents can undermine user trust, impede online activities, and have far-reaching consequences for businesses and organizations reliant on internet connectivity.
What are the Recommendations?
- Implement DNSSEC (Domain Name System Security Extensions) to authenticate DNS data and prevent DNS spoofing.
- Regularly update DNS software and apply security patches to protect against known vulnerabilities.
- Configure firewalls and intrusion detection/prevention systems to filter and block suspicious traffic targeting DNS servers.
- Use rate limiting and request filtering to mitigate the impact of DDoS attacks on DNS infrastructure.
- Employ DNS redundancy and failover mechanisms to ensure continuous service availability in case of server compromise or outage.
- Monitor DNS server logs for unusual activity and implement proactive threat intelligence to detect and respond to potential threats promptly.
- Protect administrative logins with multi-factor authentication (MFA).
How can one test to see if the DNS Server is accessible?
The easiest way to do this would be to use Nmap and see if a DNS service is open. DNS service mostly runs on Port 53, so we can test it with that to narrow the results:
nmap -sV -Pn 203.185.99.209 -p 53
Starting Nmap 7.92 ( https://nmap.org ) at 2024-06-28 10:37 EDT
Nmap scan report for 203.185.99.209
Host is up (0.30s latency).
PORT STATE SERVICE VERSION
53/tcp open domain dnsmasq 2.75The above indicates that the DNS service is available against the said IP:Port combo on the public internet.
How can the finding(s) be remediated?
SecurityScorecard allows the removal of findings if you have confirmed that the Recommendations above have been followed. The findings can be remediated using either the "Fixed" button (If the Server is no longer enabled) or using the "Other Resolution" option (If the above recommendations have been followed).