DNS spoofing is a type of cyberattack where bad actors exploit vulnerabilities in the DNS infrastructure and inject fake DNS records into the cache of a domain name server or a client’s DNS resolver. By doing so, hackers can reroute legitimate traffic toward malicious sites they control and steal sensitive data.  The DNS is responsible for translating domain names (e.g., www.coalitioninc.com) into IP addresses that computers can understand. When threat actors launch DNS spoofing attacks, they gain access to DNS servers and insert counterfeit DNS entries that redirect web users to fraudulent websites. When a user tries to visit a real website, the DNS request is intercepted and modified. The user then ends up on a fake site and is deceived into thinking it’s a legitimate server. Most web services, DNS included, were built to support availability, a critical component of the confidentiality, integrity, and availability (CIA) triad, and not for security. DNS uses user data protocol (UDP), which doesn’t require senders or receivers to verify their identities before establishing a connection. Hackers can swap fake information into the process to launch their attacks.

Threat actors use DNS spoofing attacks to conduct various malicious activities. Not only can hackers steal sensitive information and launch phishing attacks by spoofing DNS servers, but they can also distribute malware and manipulate network traffic (e.g., to commit ad fraud or launch a DDoS attack).  While there are variations and techniques within the broader category of DNS spoofing attacks, hackers primarily rely on these five methods.

1. DNS cache poisoning

In DNS cache poisoning attacks, hackers inject false DNS records into a DNS server or a client’s DNS resolver or router. This causes legitimate domain names to become associated with incorrect IP addresses. When a user tries to access a website, their system checks the DNS cache for the corresponding IP address. Since the cache has been poisoned, the user will be sent to a fraudulent website and be none the wiser. From there, the user might enter sensitive account information into their web browser or unknowingly download malware.

2. DNS server spoofing

DNS server spoofing — or DNS hijacking — occurs when a hacker impersonates a legitimate DNS server, intercepts legitimate queries, and provides fake DNS responses. As a result, traffic is redirected to unauthorized destinations that may appear to be legitimate service providers to unsuspecting users. This type of attack can also be used to eavesdrop on network traffic or launch other kinds of cyberattacks. 

3. DNS response modification

DNS response modification is a cyberattack where hackers intercept legitimate DNS responses and change them, redirecting users to different IP addresses or malicious websites. When a user sends a DNS query to a DNS server to resolve a domain name, the attacker intercepts the response and alters the information before it reaches the user’s device. Once that happens, the user is routed to an IP address the hacker controls.

4. Pharming

Pharming occurs when bad actors redirect users to fraudulent websites by manipulating DNS resolution. A user will enter a URL or click a valid link only for the hacker to send them to a fake website identical to the legitimate version. The goal is to deceive users into unwittingly sharing sensitive information, like credit card data, login credentials, or personally identifiable information (PII). 

5. Man-in-the-middle DNS spoofing

A man-in-the-middle attack (MitM) is a cyberattack where hackers intercept and change DNS communication between a client and a web server, positioning themselves in the middle of both. This enables them to eavesdrop on or modify DNS traffic. Unaware of the attack, the client receives a false DNS response and uses the manipulated IP address to establish a connection. As a result, the user is directed to a malicious website or server the hacker controls. 

No company wants to be the victim of a DNS spoofing attack. To protect against these cybercrimes, you must first know signals that may indicate your systems or devices have been compromised. Here are some methods to determine whether a hacker has targeted your organization.

Monitor DNS traffic for unusual or unexpected behavior

By observing DNS requests and responses, organizations can identify any unusual or unexpected behaviors — like a sudden surge in requests to a random endpoint or other unusual patterns that may indicate spoofing attempts. By continuously monitoring DNS traffic, it’s possible to detect DNS spoofing attack attempts in a timely fashion, enabling you to respond rapidly and minimize potential damages.

Compare DNS responses with legitimate sources for consistency

By cross-referencing received DNS responses with trusted and reputable DNS servers, organizations can ensure that traffic is routed to legitimate websites. In the event there are discrepancies or inconsistencies in any responses, it may indicate that you’re the victim of a DNS spoofing attack and that further investigation is warranted.

Implement Domain Name System Security Extensions to validate DNS responses

Organizations can enhance their ability to detect DNS spoofing by implementing DNS Security Extensions (DNSSEC) to validate DNS responses. DNSSEC adds cryptographic verification to DNS responses, which confirms their authenticity. By validating DNS responses using DNSSEC, organizations have an extra layer of protection against DNS attacks and can automatically detect and reject spoofed responses.

Audit and analyze DNS cache for unauthorized entries on a regular basis

DNS cache poisoning often leads to invalid DNS responses that send users to malicious websites. By conducting audits and analyzing the DNS cache regularly, organizations can surface unauthorized entries that could indicate a DNS spoofing attack. From there, they can take appropriate actions to mitigate the risk and secure their systems.

Utilize an intrusion detection system or networking monitoring tools

Organizations gain more visibility into network traffic by deploying an intrusion detection system (IDS) or other network monitoring tools, including DNS requests and responses. They can then analyze that data to identify anomalies or other suspicious patterns. With the right tools in place, security teams can receive real-time alerts and notifications in the event a DNS spoofing attempt occurs and then respond accordingly to reduce potential impacts.

To give you a better idea of the damage these kinds of attacks can inflict, here are three examples of real-world DNS spoofing attacks:

• In 2015, hackers used a DNS spoofing attack to take over Malaysia Airlines’ website, causing reputational harm to an airline that had already had a tough year.

• In 2018, hackers launched a DNS spoofing attack against Amazon Web Services systems, redirecting an online cryptocurrency’s website to a site they controlled. The bad actors made off with at least $17 million in Ethereum.

• In 2019, a group of hackers called Sea Turtle used DNS hijacking attacks to target 40 different organizations across multiple countries, including several government agencies.

According to a recent report from IDC, 88% of organizations experienced at least one DNS attack in 2022. What’s more, such attacks set companies back an average of $942,000 per incident. No organization wants to become the victim of a cybercrime. Consider employing one or more of these tactics to avoid falling victim to a DNS spoofing attack.

Implement DNSSEC to ensure DNS data integrity

By adding a layer of cryptographic verification to DNS responses, it’s that much easier to ensure the data being exchanged is authentic. By validating DNS responses using DNSSEC, organizations can reduce the risks associated with receiving spoofed or tampered responses.

Use DNS filtering or reputation services to block access to malicious domains

By utilizing a DNS filtering service, you can block access to known malicious domains and prevent users from connecting to potentially fraudulent or harmful websites. Such services maintain up-to-date lists of malicious domains and can filter out invalid requests to protect against DNS spoofing attacks.

Update and patch DNS server software regularly to address vulnerabilities

If there’s one thing hackers love to exploit, it’s out-of-date software. By ensuring your DNS software is always up to date, you can address potential vulnerabilities that attackers could potentially target. This, in turn, reduces the likelihood that bad actors will launch a successful spoofing attack against you.

Implement strong network security measures to prevent unauthorized access to DNS servers

Keeping bad actors out of your network starts with implementing strong network security measures — like firewalls, access controls, and network segmentation. When organizations limit access to authorized users and reinforce those controls with strict security measures, they can decrease the likelihood they fall victim to DNS spoofing. Additionally, you may also want to offer security awareness training. For example, employees should be required to use a virtual private network (VPN) whenever they’re connecting to a public Wi-Fi network. They should also know to look for a lock in their browser, which indicates a secure connection via Secure Sockets Layer (SSL).

Adopt a zero-trust approach to security

By embracing a zero-trust security approach, organizations can ensure that all requests to DNS servers are carefully authenticated and authorized — regardless of the user’s location or network. At a high level, zero-trust network access (ZTNA) grants access based on myriad factors, including identities, devices, operating systems, geolocation data, historical usage patterns, and time.  With additional security controls thrown into the mix — like multi-factor authentication, continuous monitoring, and end-to-end encryption — organizations can strengthen their security stance and reduce the chances they suffer DNS spoofing attacks.