The HOSTS file is the virtual equivalent of the phone company's directory assistance. Where directory assistance matches a person's name to a phone number, the HOSTS file maps domain names to IP addresses. Entries in the HOSTS file override DNS entries maintained by the ISP. This makes the HOSTS file a common target of malware. By modifying the HOSTS file, malware can block access to antivirus updates or force you to a malicious website. It's a good idea to check the HOSTS file periodically. Here's how to find - and edit - the HOSTS file on Windows 7, Vista, and XP.
