[RFE] [RFC] Define way / policy for the expected form of XCCDF rules' names (possible to use interrogative form instead of current's imperative one?)

Jan Lieskovsky jlieskov at redhat.com
Thu Dec 5 13:53:56 UTC 2013


Thank you for the feedback, Shawn.
(Cc-ing Peter and Martin for their opinion yet [as I can say what concrete
change could mean for SCAP content, but not what it could mean for the tool]).

----- Original Message -----
> From: "Shawn Wells" <shawn at redhat.com>
> To: scap-security-guide at lists.fedorahosted.org
> Sent: Thursday, December 5, 2013 8:10:32 AM
> Subject: Re: [RFE] [RFC] Define way / policy for the expected form of XCCDF	rules' names (possible to use
> interrogative form instead of current's	imperative one?)
> 
> On 12/4/13, 11:02 AM, Jan Lieskovsky wrote:
% 
% 
% 
% Hello folks,
% 
%   as can be seen for example in the scap-workbench demo pictures:
%   [1] https://fedorahosted.org/scap-workbench/attachment/wiki/WikiStart/browsing_results.png
%   [2] https://fedorahosted.org/scap-workbench/attachment/wiki/WikiStart/intro_screenshot.png
%   the current way how XCCDF rules' names are created is in imperative
% form (e.g. "Set / Ensure / Verify ...") instead of the interrogative
% one (e.g. "Substantive [Subject of the check] meets feature / criteria").
% 
% While this approach is natural for HTML version of the guide, the XCCDF
% rule names are used also in tools performing the scan / remediation
% (e.g. scap-workbench:
%   [3] https://fedorahosted.org/scap-workbench/ )
% 
% And this is where the source of confusion appears / might appear --
% consider the following selected cases (there are far more of them
% than just these though):
% 
%           Rule Name                         |  Scan Result
% ----------------------------------------------------------
%  Set Password Minimum Length in login.defs  |  fail
% ----------------------------------------------------------
%  Set Password Minimum Age                   |  fail
% ----------------------------------------------------------
%  Set Password Maximum Age                   |  fail
% 
% What the scan is actually doing being comparing if applied system's
% policy for the expected form of passwords:
% * doesn't allow passwords shorter than expected minimum length,
% * if there are minimum / maximum periods how long password
%   (at least / at max) should be considered as valid defined.
% 
% But based on the above presented form scap-workbench /
% scap-security-guide user, unfamiliar with the internals,
% might obtain an opinion / impressions when seeing the 'fail'
% result, that the tool actually tried:
% * to set the minimum length for passwords on the system,
% * to set minimum and maximum period during that passwords
%   should be considered valid,
% 
% and this act failed (IOW the current form migth induce a perception
% that instead of OVAL check failure [the true reason], the
% remediation failed [red herring / false positive]).

> 
> From the SSG workshops given through N.A., attendees have yet to confuse
> scanning results with remediation state. Historically this hasn't been a
> concern.
> 
> With that said, remediation capabilities are rapidly maturing. With online
> remediation becoming available, such as reflected in Šimon Lukašík's blog
> [1], I could see how users would be confused if the scan failed, or if the
> remediation did.

Yet another way how to look at the existing rule state being the presence
of "Set" might induce impression that remediation was attempted, when it
actually wasn't (like "Set the feature" the user might think just during
the scan the tool tried to "Set the feature", but it failed). Anyway,
see below.

> 
> If online remediation is attempted, and fails, the end state of the machine
> is still non-compliance. Perhaps an approach would be to extend SCAP
> Workbench (and OpenSCAP?) reporting functionality to indicate not only
> compliance state, but also if remediation was attempted?

Have filed two RFEs to indicate what's actually performed:
[2] https://fedorahosted.org/scap-workbench/ticket/141
    (display information about actually processed rule in the statusbar,
     and also information if it's scan or remediation),
[3] https://fedorahosted.org/scap-workbench/ticket/142
    (do the same but not in the statusbar, but by changing background
     color of actually processed rule [scan having one color, remediation
     another one])

Any other opinion how to distinguish these two yet / indicate which of
the two was attempted at the moment?
 
% 
% To avoid this source of confusion we propose to change the way
% how XCCDF rules are named (use interrogative form instead of
% imperative one).
%
% To mention examples for above three cases:
% * 'Set Password Minimum Length in login.defs' would become for
%   example:
%   'User Passwords In login.defs Meet The Minimum Length Requirement /
%    User Passwords Meet The Minimum Length Requirement /
%    Only Passwords Longer Than Defined Minimum Allowed'
% 
% * 'Set Password Minimum Age' could become:
%   'Minimum Period Between Password Changes Defined'
% 
% * 'Set Password Maximum Age' could be:
%   'Maximum Number of Days a Password Might Be Used Set'
% 
% Using this form (we think) the failing scan result wouldn't
% conduct to impressions, the remediation being what failed.
% 
% If we could agree on this proposal, I could come with patch
% how Fedora rules (or even RHEL6?) names should be changed
% not to (possibly) lead to this confusion.

> 
> There's been discussion on this in the past. Classically the use of SSG has
> enabled (mostly government) users to demonstrate compliance against
> requirements . These requirements are imperative, and thus many XCCDF titles
> were mostly written in this form.
> 
> A few derived profiles, such as the U.S. DoD STIG, mandate even stronger
> language ("The System shall...", "The system must...."). The ability to
> extend/rename XCCDF titles was accounted for during the U.S. DoD STIG
> process, and reflected in the STIG Overlay (note the <title> tags):
> https://git.fedorahosted.org/cgit/scap-security-guide.git/tree/RHEL6/input/auxiliary/stig_overlay.xml
> 
> If we migrate XCCDF titles to an interrogative form, we'd need to create
> XCCDF title overlays for not only the STIG, but also USGCB, NIST, FISMA, and
> almost every profile currently existing. Each overlay is some 1,500 lines
> long..... which would mean an administrative burden of at least another
> 6,000 lines of code. I'm not sure the effort + burden would be worth it.

Yeah, truly (now when written down) this looks to be not the ideal way
to go. Can understand the guide needs to have the rules in imperative form
(the standards' requirements). But your mention about overlays provided
another idea to me - what to use overlay to modify the rule names post
the HTML guide has been generated?

Like when making RPM, we would first generate HTML guide with imperative
form in rule names, then when making the content (final XCCDF mainly)
we would apply some overlay - I think it would be enough if it would move
the first verb from the beginning to the end. Like:

* 'Set Password Minimum Length' => 'Password Minimum Length Set'
* 'Set Password Maximum Age' => 'Password Maximum Age Set'
...

>From what have looked at overlay definition, this seems to be doable.
The only question now remaining being if rules named different way
couldn't introduce additional confusion (the overlay would need not to
change them "too much", like just by moving the imperative at the
end for example).

Would this be acceptable? Or not a way to go?

> 
> To clarify OVAL result vs remediation result, perhaps the tools could be
> expanded?

For now filed two RFEs (shall I find out more how it could be expanded
yet, will file them).

% 
% 
% 
% 
% 
% Comments / feedback appreciated.
% 
% Thank you && Regards, Jan.
% --
% Jan iankko Lieskovsky / Red Hat Security Technologies Team
% 
% P.S.: Prior actually requesting / proposing this change we
%       have been considering if scap-workbench tool couldn't
%       instead of XCCDF rule names display underlying OVAL
%       check titles (and have these titles customized). But
%       this approach has been realized as not possible to perform
%       because:
%       * there might be more than just one OVAL checks for one
%         XCCDF rule (in that case which one to display?),

> Having multiple OVAL mapped to a single XCCDF rule would be... challenging.
> Every XCCDF rule should reflect a unique configuration change, preferably to
> the level of having a CCE assigned.
> 
> As an idea, perhaps we should renaming the XCCDF groups to be interrogative,
> with the individual XCCDF rules being imperative?

Right now scap-workbench doesn't support / display XCCDF group names (just
rules' names). Yeah, displaying groups (via clicking on expanding tree fields)
might be more appropriate for better organization of the whole benchmark,
but I am not sure changing (just) the way XCCDF group names are created would
solve our problem.

 
% 
% * during parsing the particular XCCDF scap-workbench
%         (some other tools too?) is operating on rule IDs instead
%         of rule names so it would be difficult (if even
%         possible) to modify the code to get it to display
>         OVAL titles instead of XCCDF rule names.
> Side note, which may warrant it's own thread: Should we use XSLT to insert
> the XCCDF title automatically into the associated OVAL check? This could
> greatly reduce the maintenance burden if/when any renaming occurs.

Not sure. Martin, would this simplify the scap-workbench's parsing somehow?

 
% P.S.#2: Another possibility which comes to my mind is instead
%         to have XCCDF rules shared in both, the HTML version of the
%         guide and in the validation tool screen, we could dedicate
%         XCCDF rule names to be displayed just in the validation tools,
%         and generate rule names for HTML version of the guide some
%         other way (like keeping it in some other / yet different
%         XCCDF element and when generating HTML guide use content of
%         that element instead of XCCDF rule name).
> The maintenance burden of this would be high.

Yeah, now you described the way how STIG document is overlay-ed, I can
see the complexity. What about the vice versa approach (keep HTML rules
names intact, but post generating the guide use overlays to [slightly]
change rules' names in final XCCDF) above?

> 
> 
> Thanks for starting this thread Jan! It's a very worthwhile conversation.

No problem. Just trying common user (not aware of all underlying details) 
when using the tools not to get confused (or if they should ever get confused,
we to notice / fix it yet sooner :)).

Thank you && Regards, Jan.
--
Jan iankko Lieskovsky / Red Hat Security Technologies Team

> 
> 
> [1] http://isimluk.livejournal.com/3573.html
> 
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