Pharming

Pharming is a cyber attack intended to redirect a website's traffic to another, fake site. Pharming can be conducted either by changing the hosts file on a victim's computer or by exploitation of a vulnerability in DNS server software. DNS servers are computers responsible for resolving Internet names into their real IP addresses. Compromised DNS servers are sometimes referred to as "poisoned". Pharming requires unprotected access to target a computer, such as altering a customer's home computer, rather than a corporate business server.

The term "pharming" is a neologism based on the words "farming" and "phishing". Phishing is a type of social-engineering attack to obtain access credentials, such as user names and passwords. In recent years, both pharming and phishing have been used to gain information for online identity theft. Pharming has become of major concern to businesses hosting ecommerce and online banking websites. Sophisticated measures known as anti-pharming are required to protect against this serious threat. Antivirus software and spyware removal software cannot protect against pharming.

While malicious domain-name resolution can result from compromises in the large numbers of trusted nodes that participate in a name lookup, the most vulnerable points of compromise are near the leaves of the Internet. For instance, incorrect entries in a desktop computer's hosts file, which circumvents name lookup with its own local name to IP address mapping, is a popular target for malware. Once rewritten, a legitimate request for a sensitive website can direct the user to a fraudulent copy. Desktops are often better targets for pharming because they receive poorer administration than most Internet servers.

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