What I meant was the exact opposite. Malware would add the heavier used sites that specialize in cleaning malware to the hosts file, but with the localhost address. If a user didn't know to check there, those sites became unreachable. The user can add sites to the hosts file along with their real IP. That's closer to what the hosts file was originally intended to do. It's the other way around. With most AVs, the initial update connection is outbound and the installed AV checks with the server to see if there's newer versions of the updatable files. When malware adds the AVs update servers to the hosts file, it'll give them the localhost address, which makes it impossible for the AV to contact the server and it can't update. File integrity checkers aren't usually part of the average security package. They're mostly used by people who take security very seriously and have built layered security packages. Some of them are quite simple and check a user defined list whenever it's run. Others poll (check at a predefined interval) a list of monitored files or folders and alert if something is changed. Batch files aren't that hard. The hardest part is getting used to the syntax the different commands use. Syntax is to batch files what grammar is to language. A batch file that uses a copy to overwrite an existing file would only need to use one command, "Copy". The rest would be paths and switches. If you call up a command prompt from the start menu and enter "copy /?" you'll see the basic usage instructions for the command. Command line takes a bit of learning and getting used to, but it's powerful and can be used for many tasks, including automating common tasks like regularly overwriting a file. The users startup folder, which is on the start menu under programs is an easy way to run an app or batch file at startup. Just make a shortcut in it to the batch file or script you want run. It's not really necessary to take such measures to secure the hosts file. For most users, an occasional manual checking is sufficient. If you decide that you want to automate this task, let me know and I'll help you set it up.