Re: Commands for Limited Users

I wanted to clarify some things about limit capabilities and command
security.

Limit capabilities is part of the legacy support for systems at security
level 10 or 20. It is a tool to solve a problem you probably don't have.
It is designed to enforce a menu security system on terminals when you
have no other security.

At security level 20 (security level 10 hasn't been supported for
years), you aren't interested in managing object-level security and you
have a very small set of tools to control user actions. In this
environment, every user has *ALLOBJ rights and has the ability to run
every command. There is no "security" except that which is provided by
limit capabilities and menus. Limit capabilities and menus provide the
means of controlling what users can do in an ad hoc fashion. 

At security level 20, you don't have object-level security. As John Earl
pointed out, limit capabilities won't secure commands from non-command
line interfaces, including commands from remote servers and within
programs. It wasn't meant to. Limit capabilities was designed for menu
security and not object-level security. This behavior outside of menus
is to be expected. 

Neither FTP nor Rexec is a classic OS/400 command line interface managed
by limit capabilities functionality. Many of these types of interfaces
didn't exist when the limit capabilities support was created. If you
want to control access to commands in all interfaces (programs
included), you need an object-level security scheme.

At security level 30 or higher, you have other options for controlling
the actions of users, including object-level security. You can simulate
the functionality of limit capabilities by a combination of command
proxies, programs, specialized signon screens, and object-level
security. 

The benefit for managing limited capabilities is very small at security
level 30 or higher, especially since you can provide for similar
functionality through other means. For a similar amount of effort, you
can turn on action auditing for users and determine actual commands
being run. After an analysis of that data, you then hone your object
security plan. Well-managed object security provides a much bigger
benefit than limited capabilities. 

CHGPWD shows some of the problems with limited capabilities. The CHGPWD
command has no parameters. It's a command that almost everybody should
have access to, but it is shipped with "Allow limited user" set to
"*NO". 

Why is it OK for a capabilities-limited user to access CHGPWD by typing
"8" on the User Tasks menu (GO USER) but not type out "CHGPWD" on a
command line on the same menu? It makes no sense.
 
Limit capabilities doesn't provide real security. It doesn't provide
consistent security. Any auditor who insists on using limit capabilities
doesn't understand the issues. I could argue that its use does not
constitute a "Best Practice" in iSeries security.

Phil Ashe
NetIQ (A division of Attachmate)
1233 West Loop South, Suite 1800 | Houston, TX 77027 USA
713.418.5279 phone
phil.ashe@xxxxxxxxxxxxxx
www.netiq.com 

-----Original Message-----
From: security400-bounces@xxxxxxxxxxxx
[mailto:security400-bounces@xxxxxxxxxxxx] On Behalf Of John Earl
Sent: Wednesday, August 30, 2006 1:28 AM
To: Security Administration on the AS400 / iSeries
Subject: Re: [Security400] Commands for Limited Users

Jim,

Sorry, I should have been more clear.  This is the list of commands that
limited capabilities are allowed to run from an OS/400 command line.
But as I mentioned earlier, there are other interfaces that limited
capability users can use to run these (and other) commands.

LMTCPB users can are not restricted from running other commands from
within a compiled program - assuming they have at least *USE authority
to the command object.

jte



--
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The PowerTech Group
19426 68th Ave. S
Seattle, WA 98032
(253) 872-7788 ext. 302
john.earl@xxxxxxxxxxxxx
www.powertech.com
Celebrating our 10th Anniversary Year!
 

 
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-----Original Message-----
From: security400-bounces@xxxxxxxxxxxx
[mailto:security400-bounces@xxxxxxxxxxxx] On Behalf Of Jim
Franz
Sent: Tuesday, August 29, 2006 3:57 PM
To: Security Administration on the AS400 / iSeries
Subject: Re: [Security400] Commands for Limited Users

John - is this list commands they can execute from a
command line, or the
total list of commands they can execute, even if the
command is within
a clp program (assuming normal auth to the pgm, not
adopted, and the program
executing under the authority of the user of the program,
not the owner)?
It was my understanding that this list was a limitation of
what a limited
user
can do on a command line.
Jim Franz

----- Original Message -----
From: "John Earl" <john.earl@xxxxxxxxxxxxx>
To: "Security Administration on the AS400 / iSeries"
<security400@xxxxxxxxxxxx>
Sent: Tuesday, August 29, 2006 4:59 PM
Subject: Re: [Security400] Commands for Limited Users

Dave,

I'm reciting this from memory, so it may not be an

exhaustive list, but

if I recall correctly there were somewhere around 8

commands shipped

with the operating system that are available to limited

users.  Let's

see which ones I can remember, and then we'll see if

others can chime in

with any I may have missed.

DSPJOB
DSPJOBLOG
DSPMSG
SIGNOFF
SNDMSG
STRPCO
WRKENVVAR
WRKMSG

Of these, SIGNOFF is virtually essential, and the three

"DSP" and the

SNDMSG command are relatively inconsequential risk

(assuming you are

doing appropriate tightening elsewhere, as you have

said).  STRPCO is

risky, and probably completely unnecessary, and, absent

a specific

reason to leave them open, the WRKENVVAR and WRKMSG

could afford to be

restricted as well.

This list only includes commands that are allowed by

Limited Capability

users as shipped from the factory.  You may have more OS

commands or

application commands that have been opened to Limited

Capability users

as well.  There is at least one commercial product (uh,

why yes, that

would be a PowerTech product :) ) that will show you

this list quickly

in a single report (and help you ensure that the list

stays constant),

but I am not aware of any automated facility in the OS

that will track

this parameter for you.

HTH,

jte


--
John Earl | Chief Technology Officer
The PowerTech Group
19426 68th Ave. S
Seattle, WA 98032
(253) 872-7788 ext. 302
john.earl@xxxxxxxxxxxxx
www.powertech.com
Celebrating our 10th Anniversary Year!



This email message and any attachments are intended only

for the use of

the intended recipients and may contain information that

is privileged

and confidential. If you are not the intended recipient,

any

dissemination, distribution, or copying is strictly

prohibited. If you

received this email message in error, please immediately

notify the

sender by replying to this email message, or by

telephone, and delete

the message from your email system.
--

-----Original Message-----
From: security400-bounces@xxxxxxxxxxxx
[mailto:security400-bounces@xxxxxxxxxxxx] On Behalf Of
Turnidge, Dave
Sent: Tuesday, August 29, 2006 11:19 AM
To: Security Administration on the AS400 / iSeries
Subject: [Security400] Commands for Limited Users

I am trying to get a handle on security on our systems,
and have now
arrived at "Commands for Limited Users." I have an

Excel

spreadsheet
which has all the commands in this category on our
systems.

First, I would like to know what are the commands for
limited users that
come with the system as shipped from IBM. Second, do

you

agree with that
list? I.e., should there be ANY commands available to
limited users?

I await your reply.

Thank you,

Dave

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