RE: BugTraq Exploit for OS/400

["Neil Palmer" <neilp@xxxxxxxxxxx>]

Which is why my "RLSUPDCHG" CL program (one I run after a release update
to reapply custom changes) contains the following:

/*  DON'T GIVE OUT ANY CLUES AS TO WHETHER USER ID OR PASSWORD IS INVALID.

/*   (Change CPF1107 & CPF1120 to same generic message).
            CHGMSGD    MSGID(CPF1107) MSGF(QCPFMSG) MSG('Invalid +
                         User/Password combination.')
            CHGMSGD    MSGID(CPF1120) MSGF(QCPFMSG) MSG('Invalid +
                         User/Password combination.')

...Neil




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> Is knowledge of user ID's generally considered to be a
> "vulnerability"?

Sort of.

When attempting to compromise a target machine, any knowledge of user
accounts can often greatly reduce the time it takes to do it.

The problem with this 'vulnerability' is that you need to actually be on
the
machine to use it, although it's not quite the chicken & egg situation
that
it first sounds like - it can help once you're on the system by making
life
easier to determine which user profile(s) you *should* hijack to give you
more access rights.

A bigger 'vulnerability' in the same vein is that the sign-on screen is
quite happy to tell you too much information - it will tell you if the
user
profile  does/doesn't exist (half the battle) and then it will tell you,
once you have a valid user profile, whether you got the password
right/wrong.

Ignoring the fact that you can set the system to disable both the device &
user profile after n invalid attempts, the sign-on screen still gives too
much information, IMHO, it should just report "invalid sign-on" and not
tell
you anything else.

--phil