DNS spoofing is an attack that directs users to a fake site instead of the website they’re trying to access. It exploits a vulnerability in the UDP protocol and requires security measures like DNSSEC to prevent it.
DNS (Domain Name System) spoofing is the practice of directing internet users to a fake site when they try to access a site. This is accomplished by translating domain names into IP addresses.
In order for computers connected to the internet to identify and communicate with each other, each computer must have a unique IP address, which is created according to the Internet Protocol (IP). Protocols are communication conventions that computers use to connect and send data to each other and are implemented in software or hardware. The most commonly used IP addresses today are represented by numbers in four dot-delimited fields, such as “***.126.63.1”. This address should not be duplicated or randomized, and should be assigned a public IP address.
There are two types of public IP addresses: static IP addresses, which consistently use the same number, and dynamic IP addresses, which can be renumbered. Dynamic IP addresses are granted by a protocol called DHCP. DHCP accepts requests from computers that need an IP address and assigns it to them, and when the computer stops using the IP address, it returns the address so that another computer can use it. On the other hand, there are also private IP addresses, which are not directly accessible to the Internet and only identify each other on internal networks.
The Internet works on the basis of public IP addresses, but when we use the Internet, we use domain names instead of IP addresses, which are made up of characters for ease of use, such as ‘www..’. We need DNS to translate domain names into IP addresses, and the devices that run DNS are called nameservers. Your computer needs to have the nameserver’s IP address recorded, and while a computer with a dynamic IP address will have the nameserver’s IP address automatically recorded when it receives an IP address, a computer with a static IP address will need to have the nameserver’s IP address recorded by the user. Internet service providers operate nameservers that are shared by their subscribers.
DNS is an essential component of Internet communications, and fast and accurate domain name translation has a significant impact on the Internet user experience. DNS performance and security are especially important for sites and businesses that handle large amounts of traffic. If a DNS server goes down or is hacked, it can cause a massive service outage. For example, the Dyn DNS attack in 2016 wreaked havoc, taking down many major websites.
Let’s take a look at how a user normally connects to a site. The computer trying to access the website is called the client. When a user types the domain name of the site they want to visit into the address bar (or searches for it on a portal site and clicks on it), the client sends a query packet to the nameservers on record, asking for the IP address corresponding to the domain name. If the IP address is in its list, the nameserver sends a reply packet that tells the client the IP address. The response packet indicates which query packet it is responding to. If the IP address is not listed, the nameserver sends a reply packet that tells the client the IP address of another nameserver, and the client goes back to sending a query packet to that nameserver and repeats the process. The client uses the IP address to find the site. Nameservers and clients send packets back and forth using a protocol called UDP. To ensure that packets are sent quickly, UDP only sends packets to the other party and does not check for arrival; it trusts the first response packet that arrives for a particular query packet and discards the next one without checking. DNS spoofing takes advantage of these holes in UDP.
Let’s take a look at how DNS spoofing works. A computer infected with malicious code that performs DNS spoofing is called an attacker. When a client sends a query packet to a nameserver asking for a specific IP address, the packet is forwarded to the attacker, who sends a response packet to the client with the IP address of a fake site. The response packet from the attacker arrives at the client before the response packet from the nameserver, and the client recognizes the response packet from the attacker as the correct packet and is directed to the fake site.
Therefore, it is important to take security measures such as Domain Name System Security Extension (DNSSEC) to prevent DNS spoofing attacks. DNSSEC verifies the integrity and origin of DNS data, allowing clients to verify that the data they receive is trustworthy. Network administrators should also regularly monitor DNS servers and detect anomalous activity so that they can respond immediately. It’s also important for end users to follow basic security practices, such as using trusted security software and not visiting suspicious websites.
