Toxic blogs are been used to distribute malware and keyloggers, censorware firm Websense warns. Websense Security Labs said it has discovered "hundreds of instances" of blogs involved in the storage and delivery of harmful code this year. Anti-virus firms question why Websense has singled out blogs as a particular security risk but Websense does come up with at least one concrete example of the trick having been used in anger.
According to Websense, blogs can be attractive vehicles for hackers for several reasons — blogs offer large amounts of free storage, they rarely require any identity authentication to post information, and most blog hosting facilities do not provide antivirus protection for posted files.
In some cases, the culprits create a blog on a legitimate host site, post viral code or keylogging software to the page, and attract traffic to the toxic blog by sending a link through spam email or instant messaging (IM) to potential victims. Alternatively the blog can be used as a storage location from which PCs infected with Trojans "phone home" to get updated attack code.
For example, Websense Security issued an alert in late March detailing a spoofed email message that attempted to redirect users to a malicious blog that would run a Trojan horse designed to steal banking passwords. Targets received a message spoofed IM message, offering a new version of MSN Messenger. Upon clicking the link, the user was redirected to a blog page, which was hosting a password-stealing keylogger called bancos.ju.
"These aren’t the kind of blog websites that someone would stumble upon and infect their machine accidentally. The success of these attacks relies upon a certain level of social engineering to persuade the individual to click on the link," said Dan Hubbard, senior director of security and technology research for Websense. The firm says the risk from corrupt blogs is another good reason for firms to deploy layered security defences, such as its own Web Security Suite—Lockdown Edition.
Pete Simpson, ThreatLab Manager at security firm CLEARSWIFT, and maintainer of an IT security web log, questioned why Websense has singled out corrupted blogs as a particular security risk. "A web page is just a web page. If they were talking about spreading malware via RSS feeds I'd be more concerned," he said.
Graham Cluley, senior technology consultant for Sophos, commented that the risk Websense highlights only applies to blogs that allow code to be posted as comment. Neither CLERASWIFT nor Sophos has noted the tactic as a common attack vector though both say the use of corrupt blogs to spread malware is a possibility. ®