Re: OpenSSH 3.4p1 Privsep

From: Artem Chuprina (bugtraqat_private)
Date: Tue Sep 17 2002 - 14:00:32 PDT

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    On 2002.09.16 at 17:48:42 -0400, Andrew Danforth wrote:
    
    > During authentication, OpenSSH 3.4p1 with privsep enabled passes the
    > cleartext password from the main process to the privsep child using a
    > pipe.  Using strace or truss, root can see the user's plaintext password
    > flying by.  I observed this behavior from OpenSSH 3.4p1 built using GCC on
    > Solaris 2.8 and the current Debian OpenSSH 3.4p1 package.
    > 
    > Theo and Markus tell me that this is not an issue.  Theo says that you
    > cannot prevent root from determining a user's password.  I don't disagree,
    > but asked why OpenBSD bothers to encrypt user passwords at all if that is
    > his attitude.
    
    Because these passwords are stored. That is, if /etc/shadow is stealed by
    malicious user because of administrator's mistake, it is a challenge for that
    user to get passwords from their encrypted state. This is not an issue for
    temporary objects, that's why pipes are considered secure.
    
    > The level of effort to determine cleartext passwords, for even the most
    > inexperienced Unix administrator, is almost zero given the above.  I
    > realize that no matter how you slice it, it will be possible for root to
    > grab the password from wherever it's stored in memory.  Or recompile sshd
    > to log the password, or any number of other ways.  However, the methods I
    > just mentioned all require someone with significantly more know how than:
    > 
    > 	truss -fp `cat /var/run/sshd.pid`
    
    It is also trivial to read process' memory and so on.
    
    -- 
    Artem Chuprina <ranat_private>
    FIDO: 2:5020/122.256
    



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