Re: SECURITY.NNOV: The Bat! <cr> bug

From: Peter van Dijk (peterat_private)
Date: Mon Apr 23 2001 - 13:35:46 PDT

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    On Mon, Apr 23, 2001 at 12:06:21PM +1300, Nick FitzGerald wrote:
    > The authors of TheBat! suggest above that this problem should not be
    > their concern because the message should never arrive in such a state
    > as it is clearly not standards-compliant.  The same could be said of
    
    They're wrong.
    
    > the Outlook/OE date header problem which, IIRC, required an
    > unfeasibly long timezone value.  "Unfeasible" how?  Unfeasible
    > according to the SMTP STD which effectively defined a maximum length
    > for the Date: header's value of 30-something characters (I don't have
    > the notes I made at the time and can't be bothered checking but it
    > was well short of the length needed in just in the TZ part of the
    > header to trigger the overflow).
    >
    > Sure overflows are bad and undesirable (they reflect something about
    > the general levl of quality and security consciousness of the
    > programmers if nothing else), but is not the real problem here that
    > SMTP servers accept non-compliant messages in the first place **and
    > pass them on thus**?
    
    Not at all. SMTP servers are concerned with RFC821 (SMTP), not RFC822
    (message format). The only place where SMTP and RFC822 touch is in the
    adding of Received headers. Everything else is purely between the
    original sender and the final recipient.
    
    Lots of MTA's, however, try to enforce RFC821 compliance on
    SMTP-received and -transferred messages. All of them fail miserably,
    mutilating messages in the process and basically harming
    interoperability and message integrity.
    
    > Rather than pouring scorn on MS for the crappiness of the Outlook/OE
    > date-parsing code as if they were the "real villians" in that case,
    > shouldn't we have been pouring the scorn on the authors of the
    > non-standards compliant servers that pass these messages?
    
    No. Even if we would agree that those people are wrong (which I
    disagree to), that still leaves the Outlook/OE hole open to exploit
    for a 'malicious' server (either intentional or because it got
    hacked). That alone is reason enough to indeed blame M$ for that bug
    (and the The Bat! authors for this one, ofcourse).
    
    Greetz, Peter.
    



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