Mac-targeting Rogue MacDefender Shape Shifts into MacGuard, Becomes Even More Dangerous

Article by George Norman (Cybersecurity Editor)

on 30 May 2011

Intego, company that specializes in providing security solutions for Macs, has recently reported that the Mac-targeting rogue known as MacDefender (also known as MacSecurity and MacProtector) has shape shifted into a new, even more dangerous variant called MacGuard.

What makes this new variant more dangerous than previous versions? Why the fact that unlike previous variants of this rogue, this one does not ask the user to type in the administrator password when it installs itself and infects the user’s machine. “Unlike the previous variants of this fake antivirus, no administrator’s password is required to install this program. Since any user with an administrator’s account – the default if there is just one user on a Mac – can install software in the Applications folder, a password is not needed,” explained Intego.

The MacGuard rogue makes its way onto the user’s computer as follows:
– When the user visits a specially crafted website, a package called avSetup.pkg is automatically downloaded onto the user’s machine. The package will open Apple’s installer if the “Open safe files after downloading” option is checked in Safari.
- The user will be presented with a standard installation screen. An application called avRunner will then be installed; once the installation process completes, the installation package deletes itself.
- avRunner will then download the MacGuard rogue. The user will not be asked for his username and password at any time.

In related news, Apple has officially responded to the MacDefender rogue and its variants. It has posted an online support document in which it explains how to remove the rogue and how to make sure the rogue does not compromise your machine. Apple also said that it will release an update that will present the user with an explicit warning if he tries to download the MacDefender rogue or any of its variants and will automatically find and it will automatically remove the MacDefender rogue and its variants from compromised machines.


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