Imagine it. You sit down at your computer about to do your daily perusal of Buzzfeed  or check out The Financial Times but your homepage is now some weird search engine you've never seen before. Guess what? You've been hijacked.

Browser hijacking is when your Internet browser (eg. Chrome, FireFox, Internet Explorer) settings are modified. Your default home or search page might get changed or you might get a lot of advertisements popping up on your computer. This is done through malicious software (malware) called hijackware. A browser hijacker is usually installed as a part of freeware, but it can also be installed on your computer if you click on an attachment in  an  email, visit an infected site (also known as a drive-by download), or download something from a file-sharing site.

Once your browser has been hijacked, the cybercriminal can do a lot of damage. The program can change your home page to a malicious website, crash your browser, or install spyware. Browser hijackers impede your ability to surf the web as you please.

Why do criminals use browser hijackers?

Like other malware and scams,  hijacked browsers can bring in a good chunk of money for the hacker. For example, one browser hijacker, CoolWebSearch, redirects your homepage to their search page and the  search results go  to links that the hijacker wants you to see. As you click on these links, the cybercriminal gets paid. They can also use information on your browsing habits to sell to third parties for marketing purposes.

Browser hijackers are annoying and sometimes they can be tough to get rid of. Here are some ways to prevent your browser from getting hijacked:

• Carefully read end user license agreement (EULA)documents when installing software. Often times, mentions of browser hijackware are hidden in the EULA, so when you accept the user agreements, you might be unknowingly accepting malware.
• Be cautious if you download software from free sites. As the old saying goes, free is not always free—you may be getting additional items with your free download.
• Keep your browser software up-to-date.
• Use comprehensive security software, like the McAfee LiveSafe™ service, to keep all your devices protected.

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Robert Siciliano is an Online Security Expert to McAfee. He is the author of 99 Things You Wish You Knew Before Your Mobile was Hacked!  Disclosures.