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Leopard quarantine bug discovered

updated 10:45 am EST, Wed November 21, 2007

Leopard quarantine bug

A flaw has surfaced in Apple's Leopard quarantine system that allows unsuspecting Mac users to open specially crafted files that run with nearly any application. The quarantine system included in the latest revision of Mac OS X is designed to alert users when they attempt to open applications or disk images that arrive via Mail, Safari, or iChat. However the safety measure fails to issue a proper warning when Mail attachments posing as pictures arrive containing a resource fork which instructs the Mac to open the file using a specific application.

A proof of concept exploit created by heiss Security -- the firm that discovered the bug -- demonstrates the flaw by printing some harmless text in a terminal window after the user clicks on an image received via email, noting that the shell script could just as easily contain commands to delete all of a user's files.

Intego's sample file using Apple's Mail program appears as an attachment with a JPEG icon that will open in Preview when double clicked, but attempting to view the file with Quick Look reveals the truth about the masked shell script. Users receiving such a file might click the attachment to view the contents, trusting Apple's quarantine security measure to warn them about any unwanted applications received by email or other means.

"Until this bug is corrected in Mac OS X 10.5, Mac users are at risk of receiving maliciously crafted files, pretending to be image files, which could delete all of a user's files, or may contain Trojan horses," Intego said. "It is important that users do not open attachments from unknown senders, especially those that come with spam messages."

 
Previous Comments

Heiss

11/21, 11:18am reply

Heiss security just cleaned up a bit after their latest FUD. This is indeed a security hole for some of the users.

ViktorCode

Fresh-Faced Recruit

Joined: Jan 2006

0

common sense

11/21, 11:53am reply

The best quote is this: "It is important that users do not open attachments from unknown senders, especially those that come with spam messages."

That is just good internet common sense, no matter which OS you're using. Apple needs to fix the bug, to be sure, but internet users should always practice common sense.

wonderllama

Fresh-Faced Recruit

Joined: May 2007

0

Re: common sense

11/21, 12:56pm reply

There is that glaring problem with common sense.

It ain't so common.

Flying Meat

Fresh-Faced Recruit

Joined: Jan 2007

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Re: common sense

11/21, 02:17pm reply

Another glaring problem is that viruses can send out mail from one person's box to a user's in their address book. So the mail you get looks like its from a known person.

Oh, and I think Mail automatically displays pictures with emails, without a prompt, so just opening the mail (or highlighting it in your mailbox) may be enough to launch the corrupted graphic.

testudo

Fresh-Faced Recruit

Joined: Aug 2001

0

Doesn't Sound Good

11/21, 03:03pm reply

For a change, this is one of those "Mac Viruses" that actually has me concerned.

iFrankie

Fresh-Faced Recruit

Joined: Jul 2002

0

Nice...

11/21, 03:35pm reply

Thank you for posting such clear instruction on how to craft one of these bombs

TheSnarkmeister

Fresh-Faced Recruit

Joined: Jun 2007

0

shaking

11/21, 11:12pm reply

my email has 1000s of these in there. Oh my God!!!

relax people.

Doofuses

robttwo

Fresh-Faced Recruit

Joined: Nov 2005

0

re: common sense

11/22, 01:54am reply

"Oh, and I think Mail automatically displays pictures with emails, without a prompt, so just opening the mail (or highlighting it in your mailbox) may be enough to launch the corrupted graphic." Actually, because Mail reads the image data itself of the enclosed image, it cannot run the script. The script is launched because the user launches it by double-clicking on it. For the same reason, any image viewer would not launch the script if the alleged image is open from the File menu. This is also "common (technical) sense"...

Luke MacWalker

Fresh-Faced Recruit

Joined: Dec 2005

0

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