DNS Attack: How to prevent it

Domain Name System attacks are serious threats to Network Security because they can interfere with services and steal private data. Explore the ins and outs of DNS Attacks and learn how these cyber threats exploit vulnerabilities and strategies to safeguard your online presence. 

What is a DNS Attack?

A Domain Name System (DNS) attack is where cyber-criminals exploit vulnerabilities found in the Domain Name System of a server. The purpose of the domain name system is to translate user-friendly domain names into machine-readable IP addresses, via a DNS resolver.

The DNS resolver will first query its local cache for the domain name and IP address. If it fails to locate the records, it will query other DNS servers. Failing that, it will look for the DNS server that contains the canonical mapping of the domain.

Once found, the requesting application will store both the domain name and IP address in the local cache. Since organizations cannot directly monitor the flow of traffic between remote clients and DNS servers, DNS attacks have become a relatively easy way for cyber-criminals to compromise networks, and cause disruption.

How does it work?

Although the DNS is quite robust, it was originally designed for usability, not security. For this reason, it is vulnerable to many kinds of DNS attacks, which are explored in detail in a later section.

To carry out an attack, attackers typically take advantage of two facts. One, organizations are usually unable to monitor the flow of traffic between remote clients and DNS servers; and two, the communication between clients and the three types of DNS servers happens in plaintext. This type of unencrypted communication creates a vulnerability that attackers can exploit.

Although the specific mechanics differ from one type of attack to another, most DNS attacks involve some kind of manipulation or exploitation of the DNS to benefit the attacker. Typically, threat actors execute such attacks by intercepting the DNS query sent by the client browser to the DNS resolver. They also send a fake response to the browser before the legitimate response arrives from the DNS resolver and authoritative DNS server – one of the three DNS servers. Another popular attack strategy is to log in to a DNS provider’s website with stolen credentials and redirect DNS records.

Common types of DNS Attack

New DNS attack models emerge daily as the attackers evolve and develop new tactics. Here are just a few common examples.

• Domain Name System Highjacking: During this attack, the attacker compromises the DNS server to gain control over the target’s DNS settings. These setting modifications can lead to sensitive information theft, traffic redirection to malicious servers, or even the conduction of phishing attacks.
• Cache poisoning: Also known as DNS spoofing, cache poisoning attack targets DNS data manipulation to redirect victims to malicious websites. This happens by injecting fake information into the DNS resolver’s cache. The attacker can direct users to fraudulent websites or intercept network traffic.
• NXDOMAIN Attacks: In these attacks, the attackers flood DNS servers with multiple requests of fake domains to crash the servers.
• DNS Tunneling: The attackers encapsulate non-DNS traffic with multiple DNS packets to overrun and bypass network security. Setting up DNS as a covert channel, attackers grab data from a compromised network and create unauthorized channels for further communication.
• Fast Flux DNS: During these attacks, the IP addresses associated with the domain name are changed dynamically. This domain name swap procedure makes tracking down malicious websites or the infrastructure difficult.
• DNS DDoS: During these attacks target’s DNS infrastructure is bombarded with an enormous volume of malicious traffic, making it impossible to respond to legitimate DNS requests. This DNS resolution process disruption lets the attackers effectively block or make websites and services unavailable.

How to prevent DNS Attacks

To mitigate the risks of DNS attacks, organizations should implement measures such as using the latest version of DNS software, consistently monitoring traffic, configuring servers to duplicate, separate, and isolate various DNS functions, and implementing multi-factor authentication when making changes to the organization’s DNS settings.

When considering how to stop DDOS attacks, it’s worth thinking through a combination of best practices, security measures, and careful monitoring. Here are some strategies to prevent DNS attacks, including some specific to a cloud hosting environment:

• Audit DNS zones: Regularly review and clean up DNS records to remove outdated or unnecessary entries. This reduces the attack surface and makes it easier to spot anomalies.
• Keep DNS servers up-to-date: Regularly update DNS software to ensure DNS software has the latest security patches and improvements.
• Restrict Zone Transfers: Zone transfers should be limited to only the necessary secondary DNS servers to prevent unauthorized access to DNS data.
• Disable DNS recursion: DNS recursion should be disabled on authoritative DNS servers to prevent them from being used in DNS amplification attacks.
• Implement DNSSEC: The Domain Name System Security Extensions (DNSSEC) can help protect against DNS spoofing attacks by adding digital signatures to DNS data.
• Use Threat Prevention Tools: Use a threat feed to block requests to malicious domains. DNS threat filtering can help stop attacks early in the kill chain.

Only serve content to a list of trusted IP addresses to prevent DNS spoofing attacks. It’s also worth considering a full-featured DNS Firewall can protect against various DNS attack types and includes automatic detection for malware, domain generation algorithms, and DNS data exfiltration.

In a cloud hosting environment, additional measures can be taken. In cloud environments, organizations can use security groups and network access control lists (ACLs) to control inbound and outbound traffic at the instance and subnet levels, respectively.

Remember, the security of DNS in the cloud is a shared responsibility. The cloud provider is responsible for the security of the cloud, while the customer is responsible for security in the cloud. This includes proper configuration of domains, zones, records, and administration of user accounts.

Conclusion

Being safeguarded against a DNS attack is vital and can be made possible by understanding the intricacies of DNS attacks. The implementation of robust security measures is essential to protect against the ever-present threat of DNS attacks, ensuring the integrity and availability of online services and data.