Twitter starts scanning for malicious links

Security experts have welcomed the news that popular micro-blogging site Twitter has begun filtering content for malicious code.

Twitter has been struck several times in recent months by hackers, who have infiltrated user accounts and sent spam or malicious links to other account holders.

Social networking sites such as Facebook have also been targeted, principally because users of such sites are more likely to trust messages purporting to come from 'friends' or 'followers'.

Twitter users trying to send a message that contains a malicious link will now find the message blocked, and will see a notice stating: 'Oops! Your tweet contained a URL to a known malware site.'

"As Twitter has been getting more and more popular, it is increasingly targeted by worms, spam and account hijacking," wrote Mikko Hypponen, chief research officer at Finnish security firm F-Secure, in a blog post.

"We have recommended Twitter to start filtering traffic to fight this. They can easily do it, as all the messages go through them."

Last month security vendor Sophos called on Twitter and other social networks to filter messages, declaring that "the honeymoon is over" for such sites.