Security experts have used the European Union's annual Safer Internet Day initiative today to renew warnings about online fraud and malware, particularly on social networking sites.

The theme of this year's event is 'Think B4 U Post' and is mainly targeted at the online threats facing young people, but Phil D'Angio, online security expert at VeriSign, warned that all web users are potentially at risk.

"Most people have their name and date of birth on social networking sites like Facebook. Many also post their mobile phone numbers and email addresses," he said.

"If you throw a party and invite your friends online, criminals can then retrieve your postal address. Additional data like your mother's maiden name and your place of work are easy to find. Before you know it, you're a prime target for identity theft."

Andrew Brandt, malware researcher at security firm Webroot, also used the occasion to warn about the "myriad dangers" threatening the safety of everyone online.

"Key-logging software disguised as 'updates' are everywhere, fake security alerts pop up when you least expect them, phishing web pages are more cleverly designed than ever to steal your passwords, spam is choking email, worms stalk social networks, and even your mobile phone is at risk of malicious software designed to steal valuable information," he wrote in a blog posting.

"The big question on everyone's mind is what do you do to protect yourself?"

Brandt's advice is that users should update their machines, and switch from Internet Explorer to the Firefox browser, which he argued has two of the most effective plug-ins for security.

"NoScript blocks nearly every type of browser exploit from working, which can save your behind if you click something you shouldn't," he said.

"Web of Trust uses feedback from participants to rate the safety of web sites, and will warn you before you visit a dangerous page."