Phishing attacks remain one of the most dangerous types of cyberattacks. During tests by the U.S. Cybersecurity and Infrastructure Security Agency, 80% of organizations failed at least once, with almost 90% of email recipients sharing sensitive data — and in less than 10 minutes! Advanced techniques like DNS spoofing are one reason phishing attacks are so successful. To protect your network, learning how to identify and prevent DNS spoofing is vital.
What Is a DNS Spoofing Attack?
DNS servers help to connect users with the websites or networks they want to visit. In a DNS spoofing attack, cybercriminals redirect traffic away from a legitimate site to a malicious website instead. This is accomplished by convincing the user’s browser or computer system that the IP address for the fraudulent website is the correct one.
DNS spoofing is often used in connection with phishing and pretexting attacks. For example, a fraudulent email link takes your employees to a fake website that appears identical to the real thing. In just a few steps, cybercriminals can capture account numbers, passwords, or multifactor authentication cookies.
Important Elements in Web Navigation
To understand the technical side of DNS spoofing, it’s important to review a few key components of internet architecture:
- IP address: It’s easier for humans to remember web addresses like “www.examplesite.com,” but the machine tech behind the internet uses IP format, such as 172.217.31.255 for Google.
- DNS resolver: Internet service providers maintain DNS resolvers with a directory of nameservers, converting user website queries into IP addresses. There are also public DNS servers.
- Authoritative nameserver: Hosting providers update DNS registries with the IP addresses of client websites, and these reputable IPs are stored in large databases called authoritative nameservers.
- DNS server cache: DNS resolvers store the results of previous user queries and IP address pairings in the server’s cache for faster indexing. The next time a user looks for the same site, the DNS resolver simply delivers the cached IP address.
- Network DHCP server: Many enterprise networks use a Dynamic Host Configuration Protocol server to assign IP addresses to all users on the network automatically. This avoids the need to configure every workstation by hand.
Unfortunately, DNS servers were never designed with authentication processes in mind. Now that the internet’s scale, traffic volume, and security flaws have grown, DNS resolvers are a risk for network security.
Types of DNS Spoofing
Hackers have uncovered several ways of spoofing DNS server addresses, such as:
- Cache poisoning: Adding a false IP address/website pairing to a DNS resolver’s cache so the next users are directed to the malicious site
- Man-in-the-middle attacks: Capturing non-secure network traffic in transit (via packet sniffers, SSL hijacking, or Wi-Fi interception) and stealing login credentials for real accounts
- Rogue DHCP server: Installing an attacker-controlled DHCP server stealthily onto company networks, giving criminals the ability to set IP addresses for users remotely
- Local hosts file modification: Changing IP addresses at the device level, usually following a malware infection
As new software vulnerabilities appear, some methods become more common than others.
How Does a DNS Spoofing Attack Work?
In a DNS cache poisoning attack, cybercriminals manipulate a DNS resolver to add a malicious query/response IP address to the cache. This results in directing users to a fake or infected website.
For this type of attack to work, the attackers need to know or guess the victim’s IP address, the target client’s DNS server IP address, and the server ports involved. Armed with this information, hackers use tools like Ettercap to run an ARP spoofing program.
Essentially, the attacker queries the DNS resolver and pretends to be an authoritative nameserver simultaneously, adding a fake IP result before the real response can arrive. The harmful address ends up cached, so the DNS server uses it for further queries.
What Is the Difference Between DNS Spoofing and Poisoning?
In cybersecurity, DNS spoofing refers to an entire category of attacks. DNS cache poisoning is one of the most common types of spoofing, but it’s not the only method.
If cyber criminals gain access to a victim’s network, they can also modify the system’s hosts file. Operating systems default to this file for web traffic, so the browser goes to the malicious site directly.
What Is a Real-World Example of DNS Spoofing?
Common real-world examples show that DNS cache poisoning attacks can have several objectives and targets.
Enterprise Networks
If your organization uses a distributed platform for operations, hackers can use DNS spoofing to steal user credentials and gain access. The idea is to create a false copy of your platform and trick your employees into visiting it instead of your site. Even though your employees believe they’re logging into their work accounts, they’re really giving up critical data.
Financial Targets
Baiting attacks can also use DNS cache poisoning to direct bank customers to fake portals. In this case, employees receive an “alert” email warning of suspicious account activity. Clicking on the included link redirects to the fraudulent site.
How Is DNS Spoofing Prevented?
HTTPS protocols and TLS encryption enhance network traffic security. Administrators should also carefully configure DHCP servers to only accept trusted DNS connections.
DHCP snooping, port security tools, and network monitoring are excellent preventative measures. They add some offense to your defense, keeping an eye out for suspicious network devices, traffic, or logins.
For improved endpoint security and remote work teams, use the DNSSEC system for your website or platform. DNSSEC adds an authentication layer to conventional DNS.
Teach employees good email security habits, such as risk awareness. If possible, disable attachments and links in all external emails.
A costly but effective solution is to route traffic through a managed DNS provider. Managed DNS services can also reduce DDoS attacks.
Robust cybersecurity defenses against DNS spoofing must include risk mitigation efforts. Put simply, it’s impossible to prevent a single employee out of 1,000 from putting your organization at risk. You must have other security layers in place, such as Zero Trust policies and network segmentation.
Secure Your Network Against DNS Spoofing
The methods for preventing DNS spoofing aren’t the same for every organization. The right solution must fit your unique operations, network infrastructure, IT maturity level, and workforce needs. Discover Compyl’s powerful risk management tools for network security and compliance today.
