RE: OS/400 User Account Name Disclosure Vulnerability

["Chuck Lewis" <clewis@xxxxxxxxxx>]

Thanks Ed and I agree.

What I've done too is change the message text for the invalid sign on
attempts (as has been mentioned here and is also in the books).

Chuck

-----Original Message-----
From: midrange-l-admin@midrange.com
[mailto:midrange-l-admin@midrange.com]On Behalf Of Ed Fishel
Sent: Tuesday, March 05, 2002 1:54 PM
To: midrange-l@midrange.com
Subject: Re: OS/400 User Account Name Disclosure Vulnerability



Here are some of my opinions on this topic.

1. Is it a security exposure to know the name of other user profiles on the
system?

No. If it is a security problem to know the names of all the user profiles
on the system then it must be a problem to know the names of  some user
profiles, or even one other user profile. In my opinion, those people that
want to prevent some users from finding the names of other user profiles on
the system are practicing a form of security by obscurity. The system is
designed to compete in the business environment where knowing the name of
other users on the system is allowed.

Knowing, or guessing the name of a user profile is not a security problem,
but being able to sign-on and use that user profile would be a problem.
Good security design requires that even thought a user knows the name of a
user profile, that cannot easily guess the password of the user profile or
even know any other information about that user profile.

2. Do other systems allow users to find the same level of information?

Yes. At least all Unix systems I am aware of allow any signed-on user to
get a list of all users on the system by using a command such as: cat
/etc/passwd | scroll

Ed Fishel,
edfishel@US.IBM.COM

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