Scammers have developed a strain of Mac scareware that avoids the need to trick a mark into entering an administrative password.
Earlier rogue anti-virus strains, such as MacDefender, need permission to run, a hurdle MacGuard neatly sidesteps. MacGuard works on the premise that home users have administrator rights, meaning they don't need to enter the administrator password to install software in the Applications folder.
MacGuard downloads itself into this folder rather than the default download folder. This downloader connects to malicious IP addresses hidden in its own resources folder. The appearance of the malware means that advice to treat all unexpected requests for the administrator password with suspicion becomes moot. "This is not the sky falling, but it does change the game somewhat," writes anti-malware researcher David Harley.
Mac security specialist Intego reports that MacGuard, which it describes as a variant of MacDefender, is being distributed via various portals offering fake security scans. These portals are getting promoted through search engine manipulation. Intego has a write-up of the scam here.
After advising support staff not to help users who might be infected by MacDefender for at least a fortnight, Apple rethought its position and posted an advisory on dealing with the malware on Tuesday. Part of its advice – to cancel the installation process and not to enter admin passwords – has been rendered redundant by the arrival of MacGuard.
Sophos has charted the evolution of Mac-specific malware which it reckons is "advancing fast and taking many cues from the Windows malware scene" in a blog post here. ®