Re: CROSS SITE-SCRIPTING Protection with PHP

From: Sverre H. Huseby (shhat_private)
Date: Mon Oct 14 2002 - 08:43:02 PDT

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    [Rob Shein]
    
    |   The problem with this scheme is that it requires that the browser be
    |   party to the security.  What about a blackhat using netcat?  Bye-bye to
    |   whatever security functionality was built into the browser, and all
    |   protection contained therein.
    
    I'm talking strictly server-side here.  I'm not asking for a different
    browser.  I'm talking about how the server builds pages that it will
    send to the browser.  How it will build queries that is passed to a
    database and so on.
    
    We cannot change the clients, but we can change the server
    architecture.  Scrap all existing web programming environments and
    create a new one that:
    
      * Avoids cross site scripting by making it impossible for the
        programmer to programmatically place markup on the output stream.
        Everything written to the output stream will be automatically HTML
        encoded.  We will of course need some smart template system in
        order to merge the displayed data into some pre-defined markup.
        And yes, I realise that markup sometimes depends on the data to
        display, but smart system designers will propably be able to deal
        with that problem.
    
      * Avoids SQL Injection by making it impossible to build SQL queries
        using string concatenation and similar that requires the
        programmer to remember handling quotes, non-numeric characters and
        other constructs.
    
      * Avoids Shell Command Injection by having no constructs that make
        it possible to unknowingly pass user input to the shell.
    
    And so on.  Build a web development platform on which it is impossible
    to make the common mistakes.
    
    
    Sverre.
    
    -- 
    shhat_private		Computer Geek?  Try my Nerd Quiz
    http://shh.thathost.com/	http://nerdquiz.thathost.com/
    



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