We’ve had a couple recent instances of accidental downloading of viruses – typically variants of the SearchConduit virus, where any search you type in your browser gets redirected to some other site. A couple things you can try to attempt to avoid this hijacking include:
1) Install a “web of trust” addon (https://www.mywot.com/en/download) to the browser you use the most. When you do a search this places green, yellow, or red circles next to the site in your search results, so you can be careful. These ratings are based largely on what other people say about a site, but also somewhat on information found in databases (such as PhishTank) of recorded phishing sites.
2) If you know nothing about a site you can enter the link into the entry box of ScanUrl.net, in an attempt to determine if the site has issues before you go there. This also uses data from PhishTank, but adds to it info from Google.