Re: Postgresql security checks

Josh Kupershmidt wrote:
> On Wed, Sep 1, 2010 at 5:02 AM, Thom Brown <thom@linux.com> wrote:
>
> > SELECT usename
> > FROM pg_shadow
> > WHERE passwd = 'md5' || md5(usename)
> > OR passwd = 'md5' || md5('company_password');
>
> I think this query should be:
>
>   SELECT usename
>     FROM pg_shadow
>     WHERE passwd = 'md5' || md5(usename || usename) OR
>                    passwd = 'md5' || md5('company_password' || usename);
>
> Since the md5 passwords in pg_shadow (and pg_authid) are created as:
>   MD5(password || username)
>
> By the way, the documentation pages for pg_authid and pg_shadow don't
> mention that md5 passwords are stored in this fashion, perhaps they
> should? Or is this fact documented somewhere else I'm not seeing?

It is documented here:

    http://www.postgresql.org/docs/9.0/static/encryption-options.html
    17.7. Encryption Options
    Encrypting Passwords Across A Network

        The MD5 authentication method double-encrypts the password on the
    client before sending it to the server. It first MD5-encrypts it based
    on the user name, and then encrypts it based on a random salt sent by
    the server when the database connection was made. It is this
    double-encrypted value that is sent over the network to the server.
    Double-encryption not only prevents the password from being discovered,
    it also prevents another connection from using the same encrypted
    password to connect to the database server at a later time.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +