Dangerous game

It is well known that visiting sites offering porn, gambling and free MP3s leaves users at serious risk of falling victim to spyware and adware. However, the research by Ben Edelman and Hannah Rosenbaum reveals that those carrying out searches for innocuous subjects are at risk too.

The report looked at the websites returned for 1,394 popular keywords searches found via Google, Yahoo, MSN, AOL and Ask.

The results returned for each search term were then analysed using the Site Advisor security tool. Once installed this piece of software warns users when they browse websites known to be dangerous.

The most benign of the pages that Site Advisor flags up try to change browser settings (to redirect people to ad sites) and the most dangerous deluge users with spam or bundle adware and spyware in with downloads.

In one case signing up with one site led to a test e-mail address getting more than 300 spam messages per week.

Some of these risky sites use security flaws and loopholes in browsers to install software without users' knowledge and can lead to that machine being hijacked or to a user losing personal data.

The riskiest search terms were associated with downloads (such as "screensavers" and "free ringtones") and file-sharing (such as "Bearshare" and "limewire"). Searching under these categories returned a substantial proportion of dangerous sites.

The authors speculate that spammers and scammers are turning to websites to try to snare victims as efforts are made to stop spam before it reaches e-mail inboxes.

"Where internet users go, attackers follow," wrote the authors.

Across all searches approximately 4-6% of sites returned were flagged as dangerous. The authors noted that this was more "alarming" than it first appeared because American net users carry out almost 6 billion searches per month. This translates to 285 million clicks on these potentially dangerous sites every month.

"Even a single visit to a dangerous site can have serious and lasting implications for the average internet user," wrote the authors.

The number of risky sites increases when users click on sponsored results - the adverts generated to accompany particular search terms. Dangerous sites are two to four times as common in sponsored results found the research.

"We are troubled by the untrustworthiness of search engines' ads," said the authors.

The authors urged the search engines to get much tougher on those who buy adverts to accompany searches and expose those that abuse visitors.

"We're alarmed by the scope of these problems - by the many ways search engines lead users to sites that turn out to be untrustworthy or worse," concluded the report.