An independent testing lab in Germany has found that search engines are not 100 per cent effective at removing malicious sites from results — and Microsoft's Bing is much less effective than Google.

(Credit: AV-test)

Although most search engines have measures in place to protect users against trojans, malicious sites still manage to crop up from time to time — even in the top search results. An independent testing lab in Germany by the name of AV-Test has just completed an 18-month survey (PDF) to find out which search engines are the worst offenders.

The lab tested 40 million websites across seven search engines — Google and Bing, the world's two most popular search engines; Yandex, Russia's biggest search engine; Blekko; peer-to-peer search engine Faroo; Teoma, better known as; and Chinese search engine Baidu — and found only a very small number of malicious results returned: about 5000, or around 0.000125 per cent.

Google and Bing were both tested with around 10 million websites, and were the best at weeding out malware. However, it should be noted that there was quite a gap between the two: Bing turned up 1285 malicious sites to Google's 272.

AV-Test also cautioned that malware developers are getting sneaky, using search engine optimisation (SEO) to slip malicious websites into the top search results, since users tend to trust top results more.

Generally speaking, your chances of catching a trojan from a search engine are very low, but it never hurts to be prepared. Make sure your computer's operating system, your browser and your anti-virus software are up to date, and, if you're really worried, use AVG's Linkscanner to check URLs before you visit them.