Gmail users are warned to be on their guard against phishing attacks following news that the email 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.  The link, however, 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.
"While everyone is used to receiving suspicious communications via e-mail, these attacks arrived via the instant chat system built into Gmail.  As a result, more users may fall unwittingly into the trap," says Brett Myroff, CEO of regional Sophos distributor, Sophos South Africa.
Users who think they might have been duped are advised to change their Gmail password immediately, or risk their entire address book and correspondence, including information that may have been archived about other online accounts, quickly becoming rich pickings for the hackers.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 their Gmail account.
"You should always be wary of clicking on unsolicited links whether received over email or IM, and be extremely careful whenever a website asks you to enter your username and password for another site," Myroff adds.
TinyURL has now blacklisted the site, meaning that the link will no longer work. "There is, however, nothing to stop the hackers using other URL shortening sites or setting up alternative phishing sites to try and steal from the unwary."