Gmail users have been hit by a phishing instant messaging attack, following this week's e-mail service blackout.
IT security firm Sophos is warning Gmail users to be on their guard against phishing attacks, following news that the e-mail system has been the target of a campaign that spread via the Google Talk instant messaging chat system.
Samples intercepted by SophosLabs reveal that the unsolicited instant messages urge users to "check out this video" by clicking on a link via the TinyURL service.
However, the link directs users to a website called ViddyHo, which asks surfers to enter their Gmail usernames and passwords.
Sophos warns that the hackers behind ViddyHo could then use the details they have stolen to break into accounts, steal sensitive information and commit identity theft.
"We are all used to receiving suspicious communications via e-mail, but these attacks arrived via the instant chat system built into Gmail. As a result, more users may fall unwittingly into the trap," said Graham Cluley, senior technology consultant at Sophos.
"If you think you might have been duped, make sure you change your Gmail password immediately, otherwise your entire address book and all your correspondence, including information that you may have archived about other online accounts, will quickly become rich pickings for the hackers."
Sophos research shows that 41% of computer users have the same password for every website they access. It is therefore crucial for victims of this attack to change their passwords on any site where they are using the same password as on Gmail, said the firm.
TinyURL has now blacklisted the site, meaning that the link will no longer work. However, there is nothing to stop the hackers using other URL shortening sites or setting up alternative phishing sites.