Boot sector viruses spread by modifying the program that enables your

computer to start up.

When you switch on a computer, the hardware looks for the boot sector program –

which is usually on the hard disk, but can be on a floppy disk or CD – and runs it. This

program then loads the rest of the operating system into memory.

A boot sector virus replaces the original boot sector with its own, modified version (and

usually hides the original somewhere else on the hard disk). When you next start up,

the infected boot sector is used and the virus becomes active.

You can only become infected if you boot up your computer from an infected disk, e.g.

a floppy disk that has an infected boot sector.

Boot sector viruses were the first type of virus to appear, and they are mostly quite old.

They are rarely encountered today.

6. Browser Hijackers

cybercrime-types-of-computer-security-threats-browser-hijacker

Browser hijackers change the default home and search pages in your

internet browser.

Some websites run a script that changes the settings in your browser without your

permission. This hijacker can add shortcuts to your “Favorites” folder or, more seriously,

can change the page that is first displayed when you open the browser.

You may find that you cannot change your browser’s start page back to your chosen

site. Some hijackers edit the Windows registry so that the hijacked settings are restored

every time you restart your computer. Others remove options from the browser’s tools

menu, so that you can’t reset the start pag