Blackhole RAT threat to Mac OS X

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Early evidence of threat against OS X in the works.

A new backdoor Trojan for the Apple Mac operating system that informs the user that they have been infected has been detected.

Chester Wisniewski, senior security adviser at Sophos Canada, said that 'Blackhole RAT' does not appear to have been finished, yet is in beta format and it could be indicative of more underground programmers taking note of Apple's increasing market share.

Analysis by SophosLabs determined that it is a variant of a well-known Remote Access Trojan (RAT) for Windows known as darkComet, with its author referring to it as the 'BlackHole RAT', classified by Sophos as OSX/MusMinim-A, or 'MusMinim' for short.

“The name Black Hole is already used by a legitimate application which actually aims to increase security on your Mac by helping you get rid of potentially sensitive information such as recently-used file lists, data left in the clipboard and morem," Wisniewski said.

“MusMinim is very basic and there appears to be a mix of German and English in the user interface."

He said Its functions included:

  • Placing text files on the desktop;
  • Sending a restart, shutdown or sleep command;
  • Running arbitrary shell commands;
  • Placing a full screen window with a message that only allows you to click reboot;
  • Sending URLs to the client to open a website;
  • Popping up a fake 'administrator password' window to phish the target.

The default text that is displayed in the full-screen window with the reboot button also informs the infected user that it is a "Trojan Horse" and tells the user "I have infected your Mac computer".

It goes on to taunt the user with a comment: “I know, most people think Macs can't be infected, but look, you are infected! I have full control over your computer and I can do everything I want and you can do nothing to prevent it. So, I'm a very new virus, under development, so there will be much more functions when I'm finished."

Wisniewski said such Trojans were often found in pirated software downloads, torrent sites or "anywhere you may download an application expecting to need to install it".

"It could also be dropped by a vulnerability in your browser, plug-ins and other applications. Patching is an important part of protection on all platforms,” he said.

This article originally appeared at

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