Social networking giant Facebook has acted to stop the spread of a new computer worm that has stolen over 45,000 login credentials.
According to computer security experts, the Ramnit worm has been spreading since April 2010, but was only recently adapted to target Facebook details.
A “worm” is distinct from a normal computer virus in that it can reproduce itself without needing to attach itself to an existing program.
The new threat to Facebook users was highlighted recently by Seculert, an Israeli computer security firm. It said most of the users affected so far are British or French, The Telegraph reports.
“Our research lab identified a completely new ‘financial’ Ramnit variant aimed at stealing Facebook login credentials,” the firm said in a blog post.
“It was fairly straightforward to detect that over 45,000 Facebook login credentials have been stolen worldwide, mostly from users in the United Kingdom and France,” it added.
Facebook, that learned of the new attack on its users last week, said it has already taken action to defend them.
It said it had studied the 45,000 stolen login details and concluded that most of them were out of date. However all affected users will be forced to reset their passwords to improve security, the social network said.
“Last week we received from external security researchers a set of user credentials that had been harvested by a piece of malware,” a Facebook spokesman said.
“Our security experts have reviewed the data, and while the majority of the information was out-of-date, we have initiated remedial steps for all affected users to ensure the security of their accounts,” he said.
“Thus far, we have not seen the virus propagating on Facebook itself, but have begun working with our external partners to add protections to our anti-virus systems to help users secure their devices,” he added.