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."
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
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Joined: Jan 2006
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
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Joined: May 2007
Re: common sense
11/21, 12:56pm reply
There is that glaring problem with common sense.
It ain't so common.
Flying Meat
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Joined: Jan 2007
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
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Joined: Aug 2001
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
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Joined: Jul 2002
Nice...
11/21, 03:35pm reply
Thank you for posting such clear instruction on how to craft one of these bombs
TheSnarkmeister
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Joined: Jun 2007
shaking
11/21, 11:12pm reply
my email has 1000s of these in there. Oh my God!!!
relax people.
Doofuses
robttwo
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Joined: Nov 2005
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
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Joined: Dec 2005