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First Mac OS X Virus?
Posted by
Zonk
on Thu Feb 16, 2006 08:41 AM
from the is-nothing-sacred dept.
from the is-nothing-sacred dept.
bubba451 writes "MacRumors reports on what may be the first virus to affect Mac OS X, disguised as screenshots for the upcoming Mac OS X 10.5 Leopard. From the report: 'The resultant file decompresses into what appears to be a standard JPEG icon in Mac OS X but was actually a compiled Unix executable in disguise. An initial disassembly reveals evidence that the application is a virus or was designed to give that impression.' The virus is said to also spread via Bonjour instant messaging." Update: 02/17 00:09 GMT by P : This is not a virus, it is a simple Trojan Horse: it requires manual user interaction to launch the executable. See Andrew Welch's dissection.
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First Mac OS X Virus?
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Phew! (Score:5, Funny)
(fp?)
FUD of the day (Score:5, Insightful)
1.) Several proof-of-concept viruses have been written for OS X in the past, so this isn't the "first." They never propagate.
2.) When you download this
3.) When you run it, an admin password prompt is displayed by OS X, and you have to enter it to continue.
Like I said--FUD of the day.
Re:FUD of the day (Score:5, Informative)
What are you talking about? Admin accounts normally get password popups to do anything like this (system updates, system-wide installers, etc.). Are you saying in this specific instance it doesn't?
Re:FUD of the day (Score:4, Informative)
(http://www.usermode.org/ | Last Journal: Sunday September 04 2005, @07:28PM)
Re:Phew! (Score:5, Funny)
I wish I also got paid to be a crackhead.
Trojan Man? (Score:4, Interesting)
(http://slashdot.org/)
Somebody better wake up Apple and fix this application-looks-like-a-pretty-JPEG icon bug!!
Re:Trojan Man? (Score:5, Informative)
(http://hronia.blogalia.com/)
Re:Trojan Man? (Score:4, Informative)
Regardless, this "virus" pops up an admin password prompt, like every other proof-of-concept OS X trojan that's been written in the past, which effectively stops it in its tracks. This isn't really news except to Apple-haters who can go "SEE NOW U'VE GOT VIRUSES LOLZ."
Re:Trojan Man? (Score:5, Informative)
It's a "JPEG" because the author was clever enough to paste the icon of a JPEG onto the executable.
If the user is root, or possibly admin, the script writes files in
No kit, just a prompt.
http://www.ambrosiasw.com/forums/index.php?showto
Re:Trojan Man? (Score:5, Interesting)
How can a user differentiate between an executable file with a pretty icon and a jpeg in OSX (or Linux for that matter)? In Windows there are file extensions so a trojan with an icon will still have to be called something.exe in order to do any damage. How can I tell the difference between a binary file with an icon and a file that doesn't execute any code with the absense of extensions?
Please don't laugh
Re:Trojan Man? (Score:5, Funny)
Re:Trojan Man? (Score:5, Informative)
(http://www.hylobatidae.org/minerva/)
Actually, it seems that (as of 10.4.5, anyway) it'll show as 'YaddaYadda.jpg.app' even if you have the 'Show all file extensions' switched off - a bit of experimentation shows that if the first extension (in this case '.jpg') is a recognised file-type, then the '.app' gets shown as well.
So, from a display point of view:
Basically, if it's trying to impersonate another existing file-type, it'll tell you.
List View (Score:5, Informative)
(http://kadin.sdf-us.org/ | Last Journal: Tuesday October 16, @01:46PM)
If you choose "View as List" in the finder (equivalent to the Detail view in Windows), and then expand the window so that you can see the "Kind" column, the Finder will tell you the kind of file you're looking at. For example, Application, Picture, Document, etc.
The Finder looks at some stuff which is not visible to the user in determining this -- in addition to the ".app" file extension on Cocoa bundles, there are also the traditional Mac 'Type' and 'Creator' codes, stored in the file metadata in the resource fork. By setting a file's Type to "APPL," it becomes an executable. This is the traditional Macintosh analog to the UNIX eXecute bit (but arguably more flexible, since it also handles file typing), and is totally independent of the file name. But anything that you set this way will be clearly marked as an Application in List View, regardless of what you name it, or what kind of custom icon it has.
This is how the MP3Concept trojan worked, and how many old-school ResEdit tricks worked. You can have something that's legitimately named "Mp3Concept.mp3" and looks like an MP3 but is really an executable, by setting the Type and custom icons correctly. It's nothing new, people have been doing it for years. (There were a lot of ResEdit "hacks" that worked off of this principle -- for example, creating a dummy Excel document that gave a rude dialog when double-clicked.) I think it's because we've migrated away from OS 9 and the metadata concepts that people have forgotten how easy it is to do, and that the Mac still supports it.
Re:Trojan Man? (Score:5, Informative)
Um, why is my /Library chmod 775? It's that way on all four OS X machines that I can reach via SSH right now, two 10.4.x and two 10.3.x. Because there is no /Library/InputManagers in my /Library, so any program running under an admin account on my machine could create one. Admittedly, /Library/StartupItems being group-writable would be a much worse security violation (stuff in there runs as root at startup), and I have seen cases where installers will create one chmod 775 or 777, but I don't see any reason why a program that isn't setuid root (in other words, requiring the security dialog first) should be able to create new directories or drop files into /Library.
Anyhow, this is not a virus, it's a trojan. A virus attaches itself to existing executables (boot blocks included in the definition of "executables"). This is a trojan, and if it replicates, then it's a file-propagating worm (as opposed to the e-mail- and network- propagating worms that plague Windows). So far there is still no malware for OS X that doesn't depend upon human stupidity for propagation. Whether that be saving an e-mail attachment to disk and then double-clicking on its icon on the desktop (this thing won't auto-open while reading e-mail), or simply using bad username/password combinations allowing a brute-force break-in over SSH, there is still no sign of any kind of fully-automated malware for OS X.
In the meantime, I'm going to be doing a lot of "sudo chmod 755 /Library".
Re:Trojan Man? (Score:5, Insightful)
(http://www.stroeck.com/)
The only way would be some sort of flag that shows up on any icon that represents something executable, and that wouldn't be a fix but a completely new approach.
Re:Trojan Man? (Score:5, Interesting)
(http://www.kibbee.ca/)
Re:Trojan Man? (Score:5, Insightful)
(http://kadin.sdf-us.org/ | Last Journal: Tuesday October 16, @01:46PM)
However what I'm not sure about is how you'd make this work for MacOS bundles -- unlike UNIX applications they're not just single files; the thing that you click on in the Finder to launch a MacOS app (at least a Cocoa one) is actually a directory if you look at it in the Terminal, it just has the hidden suffix of ".app" (so for instance the program Mail in the finder is actually the directory/folder Mail.app). The actual executable file is normally buried somewhere within the folder -- usually like (appname).app/Contents/MacOS/executablefile.
I suppose what you'd have to do is put the visual flag on if a file was either a directory ending in ".app", or if the regular eXecute bit was set on a file itself.
Re:Trojan Man? (Score:4, Insightful)
(http://www.scul.org/SCUL/Pilot/Pil_Gropo.html | Last Journal: Monday May 12 2003, @07:33PM)
Re:Trojan Man? (Score:5, Insightful)
(http://www.ziggurat.ch/?ref=1597)
When I download a dmg file with Safari, I get a warning if the dmg contains an executable. (Not sure if that's Safari doing the warning or the code that mounts the archive or what.) Something like this in the code that unpacks tar files would go a long way toward fixing it.
Devon
Re:Trojan Man? (Score:5, Insightful)
(http://kadin.sdf-us.org/ | Last Journal: Tuesday October 16, @01:46PM)
I like it. Good idea.
While we're at it, maybe they can give us back our aliases in italics at the same time; that was a nice 'no brainer' feature if I ever saw one.
That will probably go over better with application developers than some sort of visual indicator on the application's icon that would mess up their pretty custom look. Bolded text is definitely the better way to go.
Re:Trojan Man? (Score:5, Informative)
(http://err.antville.org/ | Last Journal: Friday February 21 2003, @04:53PM)
It doesn't really disguise as an image. It just uses the OS X standard icon for images as its own icon. However, it does not have a jpeg extension and if you select it in the finder, you will not get a preview thumbnail, thus you would know that opening in the Preview application (which you would do by double clicking) cannot work. Maybe, if you have set your Finder not to display extensions, or just didn't pay attention, you would try to open it in another image viewer, which would fail and not do any harm.
Re:Trojan Man? (Score:5, Informative)
(http://kadin.sdf-us.org/ | Last Journal: Tuesday October 16, @01:46PM)
Actually running/logging-in as root requires either some non-trivial Terminal work, or going in through NetInfo Manager (a fairly intimidating config utility) and enabling the root account (which at least the time I did it, a few years ago, gave you some pretty stern warnings).
That's not to say that you can't have root-like privs -- the default first user on a Mac is an "Administrator," which just means that they can sudo -s and become root temporarily. However to do this you have to authenticate for every action. (Or every 5 minutes or so.) The MacOS "Administrator" level user is not as powerful as the WinXP type of Administrator (which is effectively a root account). Macs have three levels of users: root, Admins (who can sudo), and everyone else (who can't).
So yes, there are definitely ways that a clueless person could damage themselves with a trojan, if they just mindlessly type in their password into any box that comes up, regardless of the context in which they're being asked, but there is at least one more step stopping you from doing it compared to running on a Windows system.
It's not a virus... (Score:5, Informative)
(http://www.xwiz.co.uk/)
You cannot be infected by this unless you do all of the following:
1) Are somehow sent (via email, iChat, etc.) or download the "latestpics.tgz" file
2) Double-click on the file to decompress it
3) Double-click on the resulting file to "open" it
You cannot simply "catch" the virus. Even if someone does send you the "latestpics.tgz" file, you cannot be infected unless you unarchive the file, and then open it.
Re:It's not a virus... (Score:4, Insightful)
1. download it
2. double-click and decompress it.
3. double-click and execute it.
Re:It's not a virus... (Score:5, Insightful)
There is no double standard here.
Re:It's not a virus... (Score:4, Insightful)
I think people are misunderstanding how OS X handles file type icons. The file isn't presenting itself as a file of another type. If you did a Get Info, it would still say Application. On OS X, you can copy and paste any icon into file in the Get Info window. I have cool Mario icons for my various external USB drives. Someone just copied and pasted the JPEG icon in this case.
The fact that clicking this thing prompts for a password means OS X is correctly protecting you from this kind of an attack. Beyond that, anyone entering the password and enabling admin access for this program is at fault, not OS X.
Re:It's not a virus... (Score:5, Informative)
(http://www.crocker.com/)
In the windows scenario you have a real
In the Mac scenario you have an executable which is made to look like an image because its icon was changed. The computer itself knows that it isn't an image so it doesn't try to load it automatically from e-mail or web. This 'virus' is designed to trick the user. The user needs to double click and run the executable. It will then try to write into a protected directory and the OS will prompt the user for the admin password. If the user is dumb enough to click on a executable *and* enter the admin password there really isn't much else you can do. The executable never actually crashes any part of the OS to gain control of the OS and do something that the user doesn't authorize.
Hardware (Score:4, Funny)
(http://www.levik.com/)
Trojan? (Score:5, Insightful)
(http://sidde.lokalen.org/)
You have to execute it yourself, and that is why it is _not_ a virus.
Re:Trojan? (Score:5, Informative)
How can it be a virus if it is a Trojan?
OK, welcome to malware nomenclature 101. Will everyone please take their seats. Thank you. There are three basic classifications for malware:
This particular malware is a trojan (partly disguised as a jpg) which them copies itself to a new location on your drive and modifies a few commonly used applications in order to spread itself via they Bonjour discovery and file transfer mechanism in OS X. It requires human intervention to extract itself run, spread, and for download. I'd call this a virus to be clear about its functionality.
Eh? (Score:3, Funny)
Reminds me of old Applescript "hacks" (Score:5, Interesting)
Another variant was useful on computers that were proteted with OnGuard or AtEase. Simply make a script that would pop up a dialog box asking for the password. An unknowning teacher would enter the password and the script would exit... leaving behind a log file with the password in it for later use.
Nothing magical about these. Very basic trojan horses.
Consider the source... (Scor