It hijacks the links in a Google search and redirects the browser to random websites.
What kind of random website?
I ask because the way that Google is set up the results of your search could include an "AdWare" page or pages.
An AdWare page is one that is set up to include a vast array of commonly searched "words" and keep you clicking to generate income, not answer your question.
It is not a redirect page. It is not a malware, etc. It is a direct link in the search results. The page will often show up as a rudimentary web page, although they often show up as professionally built sites with good information and with numerous links to the exact or similar "words"
AdWare sites are sites that the publisher sets up "to be searched" by Google. Google returns searches by word match and popularity, so one of these AdWare sites that gets a lot of traffic will show up high in the ranks. High ranks equal "good info" in a Google search, even though it's not.
When you click on an AdWare page, Google pays them. If you click another link, Google pays them again, and again, and again...every time you click on a link within the site.
Why? Because the AdWare page fools Google into believing that it provides a direct link to the site you were hoping to get to.
Who pays for it? The site that is a paid advertiser.
A good AdWare page can generate $100K a month in revenue, at .001 of a cent at a time.
Google's analytics seek out those AdWare pages and blocks them... eventually.
Unfortunately their owners can resurrect them in short order.
What you can do.
Don't use Google
Read the link before you click.
If you arrive at a generic or B/S page go back