Hello,

the URI handling problem on Windows XP systems with IE 7 installed hits a 
lot of applications, not only Firefox (and mIRC) -- namely Skype, Acrobat 
Reader, Miranda, Netscape.

To recap: with the installation of IE 7 Microsoft 
changes the handling of URLs that are passed to the operating system on 
Windows XP. After this, URLs that contain an invalid "%" encoding can 
launch abitrary programms. One example is:

mailto:test%../../../../windows/system32/calc.exe".cmd

that launches the calculator when activated in affected applications. 
Firefox fixed this problem in 2.0.6. After being notified by heise 
Security, Skype fixed the problem in 3.5.0.239.


Still vulnerable (as of 4th of October) are:

Adobe Acrobat Reader 8.1: If a user clicks on such a link
in a PDF, calc.exe is executed.

Miranda v0.7: If a user klicks on this link in a chat window, calc.exe is 
executed

Netscape 7.1: mailto is handled by Netscape itself, but 
similar telnet:-links start the calculator.

This list can propably be extended with little effort.


On a question to MSRC if Microsoft is planning to react on this, we 
recieved the following response:

"After its thorough investigation, Microsoft has revealed that this is 
not a vulnerability in a Microsoft product." 


For further information see:

http://www.heise-security.co.uk/news/96982

bye, ju


-- 
Juergen Schmidt   editor-in-chief   heise Security     www.heisec.de
Heise Zeitschriften Verlag,    Helstorferstr. 7,       D-30625 Hannover
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