Re: IE SSL Vulnerability

From: Torbjörn (torbjorn.hovmarkat_private)
Date: Thu Aug 08 2002 - 13:29:59 PDT

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    Mike,
    
    I have checked out your sample exploit, and I can confirm that my IE 5 is 
    vulnerable. Regarding the post by Alex Loots, the certificate is a regular 
    server certificate, not an intermediate CA with name constraints (if I 
    have understood his message correctly) and the error certainly is in the 
    client software and not anywhere else.
    
    Is the error in the browser itself or is it in CryptoAPI? What about 
    earlier versions of IE - are they vulnerable too. Are other Microsoft 
    products that do certificate chain validation, such as IIS, vulnerable?
    
    I agree that this is very, very serious, as it can easily be exploited 
    against a large number of people at the same time, with very little risk 
    of detection. There is not much that can be done to remedy the problem on 
    the server side. A partial remedy would be to demand client certificates, 
    but in most cases that requires completely changing the security 
    infrastructure. SSL is used to protect most Internet banks. If SSL (or 
    rather the IE implementation of SSL) can be broken this easily, it is very 
    worrying indeed.
    
    Best regards / Torbjörn Hovmark
    
    ______________________________________
    Abtrusion Security AB
    http://www.abtrusion.com
    



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