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What Is DNS Spoofing and Poisoning? Detecting and Preventing Poisoned Caches

DNS spoofing (or DNS poisoning) is a cyberattack where a malicious actor corrupts DNS data to redirect users to fraudulent websites without their knowledge.

What is DNS Spoofing?

Domain Name System (DNS) spoofing, sometimes referred to as DNS hijacking, DNS redirection, DNS poisoning, or cache poisoning, is a type of cyberattack where traffic is maliciously diverted from a legitimate site to a fake site.

Spoofing happens when a DNS server resolves a domain name to a malicious IP address, often without the user’s knowledge. These fake sites can harvest login credentials or deliver malware while appearing to be a trusted source.

Understanding the meaning of DNS poisoning is critical, as attackers exploit vulnerabilities to insert fake records into DNS caches, making redirection persistent. Similarly, it's crucial to understand cache poisoning. It occurs when this altered DNS data is stored, leading to repeated misrouting of users.

To prevent DNS information from being altered, organizations should implement Domain Name System Security Extensions (DNSSEC), enforce Hypertext Transfer Protocol Secure (HTTPS), and regularly update DNS infrastructure. Monitoring tools like dig, nslookup, and threat analytics platforms help detect anomalies early.

Effective DNS spoofing prevention starts with layered defenses because spoofing happens when DNS integrity is left unprotected.

DNS Poisoning vs. DNS Spoofing

While the terms DNS poisoning and DNS spoofing are used interchangeably, there’s a subtle difference between the two:

  • DNS Poisoning is the method attackers use to compromise and replace DNS data with a malicious redirect.

  • DNS Spoofing is the end result, where users are redirected to the malicious website via a poisoned cache.

In short, DNS poisoning is the route, and DNS spoofing is the goal: hackers poison a DNS cache to spoof a DNS.

How Does DNS Poisoning Work?

When you navigate to a website, you type the domain name into a web browser and press the enter key. This sends a DNS request to a DNS server. The DNS server translates the domain name in the query into an IP address.

The DNS server resolves the request by sending the IP address associated with the domain name back to the user. The browser navigates to the domain and loads up the site you were looking for.

But what if the DNS server returns an incorrect IP address? That’s exactly what happens when a DNS is poisoned and spoofed.

Consider this scenario: you’re searching for a street, but all the street signs have been swapped. You think you’re on 42nd, but you’re actually on 52nd. To make matters worse, your GPS has also been tricked.

Replace the street signs with domain IP addresses and your GPS with your DNS server. That’s how DNS poisoning or spoofing works. Here are the steps showing how it happens:

  • A hacker alters IP addresses attached to domains in a DNS server with a fake DNS entry.

  • When a user attempts to navigate to a specific domain, the DNS server sends them to the IP address associated with that domain.

  • The hacker has altered the IP address in the DNS server, so the user is unknowingly sent to an incorrect IP address.

  • The IP address returns a domain that looks like the user's intended site.

  • The user interacts with the copycat site and attempts to login, unknowingly sharing their password and username with the hacker.

There are a few methods to conduct DNS poisoning and spoofing, including:

  • Compromising a DNS server: An attacker directly hijacks a DNS server to reroute traffic from legitimate sites to other IP addresses.

  • Man in the Middle Attacks: An attacker positions themselves between your browser and a DNS server to route you from to a malicious IP address.

Regardless of the method, the result is the same: redirecting web traffic away from its intended destination.

How To Detect and Prevent DNS Poisoning?

Detecting DNS poisoning is challenging, but with the right tools and proactive monitoring, organizations can identify and stop attacks before they cause damage.

Detecting Spoofed Domains

How to Detect DNS Poisoning

You can potentially detect DNS poisoning through these signs:

  • A significant change in DNS activity on a domain. This includes DNS activity from a single source to a single domain or multiple domains.

  • A sudden, inexplicable drop in web traffic.

If you suspect your site is a victim of DNS spoofing, test it out. Access your site using a VPN or a computer you don’t normally use. If you’re redirected to an unfamiliar site, your cache may be poisoned.

Prevent DNS Poisoning

Detecting DNS spoofing is a reactive measure. Ideally, you’ll have safeguards in place to prevent DNS poisoning from happening in the first place. These safeguards include:

  • Enable DNSSEC for your domain

  • Use a secure hosting service and CMS with SSL authentication

  • Regularly update your DNS software

  • Require HTTPS for all incoming traffic

  • Adopt zero trust configuration for other DNS servers

Protect your organization from stealthy DNS poisoning and spoofing attacks with Abnormal. Our AI-powered security platform detects anomalies, prevents redirection threats, and secures email and web traffic before damage occurs.

Request a demo today to see how Abnormal can help stop DNS-based attacks before they reach your users.

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