[Servercert-wg] Ballot SCXX: Security Requirements for Air-Gapped CA Systems

[Wayne Thayer]

Ben,

I have some questions about the proposed language.

On Mon, Nov 2, 2020 at 10:19 AM Ben Wilson via Servercert-wg <
servercert-wg at cabforum.org> wrote:

>
> 5. GENERAL PROTECTIONS FOR AIR-GAPPED CA SYSTEMS
>
> This Section 5 separates requirements for Air-Gapped CA Systems into two
> categories--logical security and physical security.
>
> Logical Security of Air-Gapped CA Systems
>
> Certification Authorities and Delegated Third Parties SHALL implement the
> following controls to ensure the logical security of Air-Gapped CA Systems:
>
> a. Review static configurations of Air-Gapped CA Systems at least on an
> annual basis to determine whether any changes violated the CA’s security
> policies;
>

Is "static" necessary here, or would it be clearer just to "review
configurations"?

The phrase "...to determine whether any changes violated the CA’s security
policies;" seems unnecessary and a bit confusing (changes to static
configurations?).


> b. Follow a documented procedure for appointing individuals to Trusted
> Roles on Air-Gapped CA Systems;
>

A "Trusted Role on a system" doesn't make sense to me. I think the meaning
here is "...to any Trusted Roles that grant the individual privileges on
Air-Gapped CA Systems;"

c. Grant logical access to Air-Gapped CA Systems only to persons acting in
> Trusted Roles and require their accountability for the Air-Gapped CA
> System's security;
>

How does a CA "require their accountability"? I'm skeptical that this part
of the requirement adds value, and it seems better suited for BR section
5.3 (Personnel controls).

d. Document the responsibilities and tasks assigned to Trusted Roles and
> implement "separation of duties" for such Trusted Roles based on the
> security-related concerns of the functions to be performed;
>

How is "separation of duties" relevant in the context of Air-Gapped
systems? In my experience, operations on Air-Gapped systems are performed
in ceremonies and include multi-party authentication. I'm concerned that
this requirement could be interpreted as adding requirements that don't fit
those processes.

e. Ensure that an individual in a Trusted Role acts only within the scope
> of such role when performing administrative tasks assigned to that role;
>
> f. Require employees and contractors to observe the principle of "least
> privilege" when accessing, or when configuring access privileges on,
> Air-Gapped CA Systems;
>
> g. Require that all access to systems and offline key material can be
> traced back to an individual in a Trusted Role (through a combination of
> recordkeeping, use of logical and physical credentials, authentication
> factors, video recording, etc.);
>
> h. If an authentication control used by a Trusted Role is a username and
> password, then, where technically feasible require that passwords have at
> least twelve (12) characters;
>
> i. Review logical access control lists at least annually and deactivate
> any accounts that are no longer necessary for operations;
>
> j. Enforce Multi-Factor Authentication OR multi-party authentication for
> administrator access to Air-Gapped CA Systems;
>
> k. Identify those Air-Gapped CA Systems capable of monitoring and logging
> system activity and enable those systems to continuously monitor and log
> system activity. Back up logs to an external system each time the system is
> used or on a quarterly basis, whichever is less frequent;
>
> l. On a quarterly basis or each time the Air-Gapped CA System is used,
> whichever is less frequent, check the integrity of the logical access
> logging processes and ensure that logging and log-integrity functions are
> effective;
>
> m. On a quarterly basis or each time the Air-Gapped CA System is used,
> whichever is less frequent, monitor the archival and retention of logical
> access logs to ensure that logs are retained for the appropriate amount of
> time in accordance with the disclosed business practices and applicable
> legislation.
>
> n. Reserved for future use
>
> o. Reserved for future use
>
> Physical Security of Air-Gapped CA Systems
>
> Certification Authorities and Delegated Third Parties SHALL implement the
> following controls to ensure the physical security of Air-Gapped CA Systems:
>
> p. Grant physical access to Air-Gapped CA Systems only to persons acting
> in Trusted Roles and require their accountability for the Air-Gapped CA
> System’s security;
>

Same comment as above on accountability.

q. Ensure that only personnel assigned to Trusted Roles have physical
> access to Air-Gapped CA Systems and multi-person access controls are
> enforced at all times;
>
> r. Implement a process that removes physical access of an individual to
> all Air-Gapped CA Systems within twenty four (24) hours upon termination of
> the individual’s employment or contracting relationship with the CA or
> Delegated Third Party;
>
> s. Implement video monitoring, intrusion detection, and intrusion
> prevention controls to protect Air-Gapped CA Systems against unauthorized
> physical access attempts;
>
> t. Implement a Security Support System that monitors, detects, and reports
> any security-related configuration change to the physical access to
> Air-Gapped CA Systems;
>

I'm not convinced that the NCSSR definition of Security Support System fits
here. Would feeding the logs from a physical security system into a CA's
logging and monitoring pipeline satisfy this requirement?

u. Review all system accounts on physical access control lists at least
> every three (3) months and deactivate any accounts that are no longer
> necessary for operations;
>

What does "system accounts on physical access control lists" mean? Are we
talking about logical access to physical security systems?

v. On a quarterly basis or each time the Air-Gapped CA System is used,
> whichever is less frequent, monitor the archival and retention of the
> physical access logs to ensure that logs are retained for the appropriate
> amount of time in accordance with the disclosed business practices and
> applicable legislation.
>
> w. On a quarterly basis or each time the Air-Gapped CA System is used,
> whichever is less frequent, check the integrity of the physical access
> logging processes and ensure that logging and log-integrity functions are
> effective.
>
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