Fwd: Vuln. MacOSX/Safari: Remote help-call, execute scripts

[Troels Bay <troelsbay () troelsbay dk>]

I usually complain a lot about the Windows-security settings, and consider *NIX systems to be of an entirely different level. But this time I found my own arguments off short.

I'm an OS X user, and I would like to submit to you the latest exploit for this system. As I hope a fix will be running in soon... Perhaps the more people who know, the sooner a fix will be up (I might be considered naive here...)

The Setting:

The Help-application of OS X uses ordinary html-pages to display troubleshooting/etc, and parses a special command when displaying help-links that, for instance, open System Preferences, Finder etc. This command uses a built-in protocol called "help:" and can easily be exploited since Safari (the default browser, and possible every other browser on the system) can use the same protocol - probably due to the Help-application's dependency on the Safari html-engine. 

This means that a simple homepage meta redirect call can use it, without the user having to do anything but surf to the site, or it can be a simple href link on the site (most often connected to a "Porn HERE" picture). This is an example of how it works:

help:runscript=../../Scripts/Info Scripts/Current Date & Time.scpt

Use:
This, placed as a link on a homepage, will trick Safari to 1) open the Help-application 2) open the "Current Date & Time" script. Though the Date & Time script is pretty harmless, consider that one can (through another link or meta redirect call) use the disk:// protocol to mount a script on /Volumes/danger.scpt and then let the link from above execute it, by altering the path.

Vulnerable Systems:
Mac OS X 10.3
(probably will work with 10.2 as well, but I cannot test that, someone please confirm?)

Risk:
This can potentially wipe the entire hard-disk (or large parts of it), if a hacker runs a script with "rm -rf /" included.

Solution:
Alter the "help:" protocol to use another application than "Help" (for quick editing use "MisFox" or "Default Apps"-3rdparty prefpane)

The funny thing is that this newly assigned application (in my case a Chess program) will open whenever a hacker tries to use the vulnerability, or whenever you rightfully try to use the Helper-application's special links.

Credits:
I can only be seen as the messenger here, the real credits are to be found on the forums of macnn: http://forums.macnn.com/showthread.php?s=&threadid=213043&perpage=50&pagenumber=1


Off topic:
I'm still waiting for that psexec tool look-a-like for *NIX, I hope some people are working on it, perhaps samba could get a grip and implement "NET SERVICE" anytime soon.