Bing search results are more affected by poisoning than those of other search engines, according to a study by SophosLabs.

Search engine poisoning attacks are designed to skew results so that dodgy sites - anything from malware infected websites to payday loan sites - appear prominently in the index of sites related to popular search terms. In many cases the tactic is so successful that malware sites appear in the first page of results for popular search terms, in sometimes much higher than legitimate websites. More recently, miscreants have began trying to manipulate image search results.

SophosLabs blocks attempts to "redirect" surfers from search engines to dodgy sites and can therefore monitor the scale of search engine poisoning attacks. Two thirds (65 per cent) of the poisoned search results blocked by Sophos appliances over the last two weeks originated from Bing while 30 per cent came via Google. The other 5 per cent came via alternative search engines. The true state of play is probably even worse than these raw statistics suggest because Google is the most popular search engine, a factor not accounted for in these raw figures.

The vast majority of dodgy redirects (92 per cent) blocked by Sophos related to image searches. Only eight per cent related to text searches.

Search engines attempt to remove malicious sites from their indexes but this involves playing a game of cat and mouse in which the search engines are by no means always successful.

“Search engine poisoning can be very dangerous for internet users, as they trust the search engine they’re using to filter out malicious links, and in this case it seems to be Bing which is letting internet users down,” said Fraser Howard, principal virus researcher, Sophos. “All search engines will miss attempts to poison their search results however, and with very few give-away clues to spot infected image searches for example, the users themselves may also struggle to detect and avoid infected search results.”

Fraser compiled these figures after being asked to look into the use of search engine result poisoning in the promotion of payday loan outfits, an issue covered in a recent Daily Mirror article.

A run-down of Sophos' results (along with illustrated examples of search engine poisoning in action) can be found on the security firm's Naked Security blog here. ®