- DNS spoofing also known as pharming attack. As we know, using the Domain Name System (DNS), people can identify Web sites with human-readable names (Such as yahoo.com). And computers can continue to treat them as IP addresses (such as 120.10.81.67). For this, a special server computer called a DNS server maintains the mappings between domain names and the corresponding IP addresses. The DNS server could be located anywhere. Usually, it is with the Internet Service Provider (ISP) of the users. With this background, the DNS spoofing attack works as follows.
- Suppose that there is a merchant (Bob) whose site’s domain name is bob.com. And the IP address is 100.10.10.20. Therefore, the DNS entry for Bob in all the DNS servers is maintained as follows: www.bob.com 100.1 0.10.20
- The attacker (say, Trudy) manages to hack and replace the IP address of Bob with her own (say 100.20.20.20) in the DNS server maintained by the ISP of a user, say Alice. Therefore, the DNS server maintained by the ISP of Alice now has the following entry: bob.com 100.2 0.20.20
- When Alice wants to communicate with Bob’s site, her web browser queries the DNS server maintained by her ISP for Bob’s IP address, providing in the domain name (bob.com). Alice gets the replayed (Trudy’s) IP address, 100.20.20.20.
- Now Alice starts communicating with Trudy, believing him to be Bob.
- Such attacks of DNS spoofing are quite common and cause a lot of havoc. Even worse, the attacker does not have to listen to the conversation on the wire. He has to simply be able to hack the DNS Server of the ISP and replace a single IP address with his own.
- A protocol called as DNSSec is use to repeal such attacks.
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