Thousands of Twitter users are believed to have been hit with malicious links tied to a rogue antivirus scam circulating the microblog service.
The scam is spreading through malicious links abusing the goo.gl URL shortening service. According to Kaspersky Lab, the malicious links redirect users to different domains with an "m28sx.html" page. That HTML page redirects users to a static domain with a Ukrainian top-level domain. From there, blogged Kaspersky Lab Senior Malware Researcher Nicolas Brulez, the domain redirects the user to an IP address pushing fake antivirus.
"Once you are on this website," Brulez blogged, "you will get [a] warning that your machine is running suspicious applications and you are encouraged to scan it. ... The user is invited to remove all the threats from their computer, and will download a fake Anti Virus [sic] application called 'Security Shield.'"
Del Harvey, director of Trust and Safety for Twitter, tweeted during the day that the company was working to remove the malicious links and reset passwords on compromised accounts.
"What isn't yet clear is how the Twitter users found their accounts compromised in this way," blogged Graham Cluley, senior technology consultant at Sophos. "The natural suspicion would be that their usernames and passwords have been stolen. It certainly would be a sensible precaution for users who have found their Twitter accounts unexpectedly posting goo.gl links to change their passwords immediately."
These kinds of attacks are hardly new to Twitter. In December, users were targeted with shortened links that redirected them to the compromised site of a French furniture company before passing them on to other domains. In that case, the malicious URLs pointed to a copy of the Neosploit attack toolkit.