MUAs that delete spoolfiles (was Solaris /usr/bin/mailx exploit (SPARC))

From: Rich Lafferty (richat_private)
Date: Tue May 15 2001 - 14:00:43 PDT

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    On Tue, May 15, 2001 at 02:15:45PM +0100, Andrew Hilborne (andrew.hilborneat_private) wrote:
    > > 
    > > (At least not if you /var/mail directory has the standard 1777 permissions)
    > > 
    > > By forcing a file permission of 600 on mailboxes, group mail should not
    > > gain you anything.
    > 
    > Just how do you force 0600 on mailboxes which don't exist (many MUAs remove
    > empty mailboxes?)
    
    If that's true, then even *without* this particular bug in Solaris,
    there's an icky denial of service attack waiting to happen. Sticky
    mailspools are awfully common these days, and all that stops Bob from
    doing
    
      touch /var/spool/mail/alice
    
    and causing the MTA to refuse to deliver is that Alice's mailbox
    should never *not* be there in the first place. 
    
    Which MUAs behave in the way you describe?
     
    > Since you cannot easily do this, at the very least a malicious user should be
    > able to steal other users' mail. I think.
    
    If they can, then *that's* a flaw in the MTA, which should never
    deliver into something that isn't owned by the recipient.
    
      -Rich 
    
    -- 
    ------------------------------ Rich Lafferty ---------------------------
     Sysadmin/Programmer, Instructional and Information Technology Services
       Concordia University, Montreal, QC                 (514) 848-7625
    ------------------------- richat_private ----------------------
    



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