Crooks have developed a new Mac OS X-specific Trojan that mimics the behaviour of a legitimate software installer.
Trojan-SMSSend-3666, which poses as an application for listening to music on a popular Russian social networking site, attempts to hoodwink marks into handing their mobile number to activate the radio app. Users are asked to enter their phone number into an appropriate field and then specify the code sent to the mobile in an SMS.
In the process victims are charged for a premium-rate text message and sign themselves up for regular debits. In return, they get nothing beyond an application that can be downloaded for free from elsewhere on the net, at best.
"The malicious scheme used to spread this Trojan is notorious among many Windows users but until now it hasn't been employed to deceive owners of Macs," notes Russian antivirus firm Dr Web.
Trojan-SMSSend-3666 was built using "affiliate programme" ZipMonster, which helps fraudsters craft fake installers and assists in collecting payments for the distributors of the malware. Crooks have been encouraged to migrate from cooking up fake Windows installers to creating fraudulent Mac OS X apps, in this case a fake VKMusic 4 for Mac OS X set-up utility.
Dr Web has a full write-up of the threat, including screenshots, in a blog post here. The Next Web notes that Apple has updated its virus definition files to block the scam.
This won't, of course, prevent possible future variants of the malware emerging, which may appear under a slightly different guise. The days of Windows-only desktop malware are long over, certainly since the appearance of the Flashback Trojan this year. If you're an Apple Mac OS X user on the web, caution is advised.
Fake installer scams have already been seen in the field of smartphone malware. Some notable cases of premium service abusers include malicious versions of Bad Piggies and Adobe Flash Player for Android, Trend Micro reports. ®