Re: Claimed Postfix Vulnerabilities

From: der Mouse (mouseat_private)
Date: Mon Dec 21 1998 - 12:38:51 PST

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    > 4 - Claim: a local user can make hard links to Postfix maildrop
    >     queue files and thus prevent mail from being delivered.
    
    >     Response: the mail will be delivered.  When a queue file has
    >     more than one hard link, Postfix deletes the hard link, and
    >     logs a warning.  When the hard link count reaches 1, Postfix
    >     delivers the mail.
    
    This sounds as though the claim is actually true.  Notice that the
    malicious-user-created hardlink does not have to be in the Postfix
    queue directory; it can be in any directory that user can write to on
    that filesystem.  Postfix will then discard (and gripe about) all the
    hardlinks in its queue directory.  (The user can then blow away the
    created link(s) and the mail will silently vanish, without, as far as I
    can tell, any way to trace after the fact who did it.)
    
                                            der Mouse
    
                                   mouseat_private
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