Re: Security Flaw in Cookies Implementation

From: der Mouse (mouseat_private)
Date: Sat Dec 26 1998 - 08:47:06 PST

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    > I have discovered what I beleive to be a flaw in the implementation
    > of cookies, that allows for possible security implications.
    > http://www.paradise.net.nz/~glineham/cookiemonster.html
    
    I particularly agree with the following text, taken from the URL I
    quoted above:
    
            It has been pointed out to me that the whole idea of counting
            dots to determine valid domain settings for cookies is a
            fundamental flaw in the specification.
    
    Consider my domain, for example: rodents.montreal.qc.ca.  Any
    specification that allows any server not under rodents.montreal.qc.ca
    to set cookies to be sent to any server that *is* under that domain is
    broken.  As I read it, the spec (if correctly implemented) would allow
    any .montreal.qc.ca server to set cookies to be sent to my web server
    (if I had one).  That is, I can extend the statement that
    
            Any country that operates subclassification of its domains is
            susceptible.  [...]  Countries that do not subclassify their
            domains are not susceptible.
    
    by pointing out that places that have additional levels of
    subclassification (like .montreal.qc.ca, or .k12.XX.us) will be
    susceptible even if the spec is correctly implemented.
    
    The spec is also broken in that it hardwires in, for all time (or at
    least for the useful lifetime of extant browsers, which amounts to much
    the same thing in practice), the list of `generic' top-level domains.
    Creating a new generic TLD will break it.
    
                                            der Mouse
    
                                   mouseat_private
                         7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B
    



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