In today’s interconnected world, DNS (Domain Name System) plays a crucial role in directing traffic to the right web resources. However, it’s not immune to attacks. One such significant threat is DNS Cache Poisoning. This attack can have severe consequences for both users and businesses alike, causing web traffic to be misdirected to malicious sites without the victim’s knowledge. Despite DNS's critical role, organizations often prioritize enhancing application and network security, overlooking the importance of DNS security and the very fact that DNS services are also vulnerable to DDoS and other attacks. In this blog post, we’ll dive into what DNS cache poisoning is, and explore ways to prevent it.

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What is DNS Cache Poisoning?

DNS cache poisoning is an attack in which a malicious actor injects false DNS data into a DNS resolver’s cache. When this happens, users querying the DNS server will receive falsified DNS responses, often directing them to fraudulent or malicious websites instead of the intended domain. This can lead to phishing attacks, data theft, or malware infections.

The key to this attack lies in exploiting vulnerabilities within the DNS caching system. Once a malicious DNS entry is cached by a resolver, it remains there until its TTL¹ (Time-to-Live) expires.

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How to Prevent DNS Cache Poisoning

Fortunately, there exists a remedy: the DNS Security Protocol (DNSSEC).

DNSSEC is a suite of extensions that adds a layer of security to DNS by allowing DNS responses to be cryptographically signed. When DNSSEC is enabled, the DNS server signs its responses with a private key. DNS resolvers that support DNSSEC can then verify the authenticity of these responses using the corresponding public key. This prevents attackers from tampering with DNS records and injecting false data, as any alteration would break the cryptographic signature.

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Advantages of DNSSEC

• Authentication of DNS data: DNSSEC ensures that DNS responses come from the legitimate source and have not been altered.
• Protection against man-in-the-middle attacks: It prevents third-parties from being able to forge records and guarantees a domain's identity.
• End-to-end integrity: It offers a method to validate the integrity of DNS responses from the authoritative DNS server to the resolver.
• NSEC/NSEC3: Verifies the non-existence of a record name and type as part of DNSSEC validation. 

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Disadvantages of DNSSEC

• Management intricacies: The key challenges primarily revolve around managing certifications and Key Signing Key (KSK) rollovers, posing challenges for organizations lacking proficient resources in this area. Most other facets of DNSSEC are typically automated by the DNS provider.
• Increased DNS response size: DNSSEC adds extra data to each DNS response (signatures), which can increase the size of the DNS packets. This may affect performance, particularly for Name Servers.
• Not all resolvers support DNSSEC: While adoption is increasing, not all DNS resolvers validate DNSSEC signatures, potentially leaving some users unprotected.
• Low Deployment Rate: Few DNS owners/administrators enable DNSSEC, and not many clients validate DNS responses. This validation often depends on the specific application client, as not all applications are integrated with the validation process.

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How Nexusguard Can Help You

Alongside the implementation of DNSSEC, an additional best practice involves configuring a lower TTL at an optimal level, combined with DNSSEC, to yield significant benefits. This is precisely where Nexusguard's DNS Protection shines by addressing two pivotal elements at once. Our resilient DNS infrastructure seamlessly incorporates DNSSEC, ensuring peak performance even amidst heavy query loads. Additionally, our transparent flat-fee pricing model shields businesses from unexpected cost spikes, even during periods of heightened DNS query activity.
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Secure your DNS today with Nexusguard’s robust DNS Protection service. Reach out to us for a free consultation and see how we can safeguard your DNS infrastructure against attacks like DNS cache poisoning.

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¹ The TTL (Time-to-Live) value of a DNS record specifies how long a DNS resolver is allowed to cache a DNS response before discarding it and querying the authoritative server again.

Whether you’re protecting your DNS infrastructure from tampering or ensuring fast, secure DNS resolution, Nexusguard’s DNS Protection service delivers the peace of mind you need.