[secdir] Review of draft-ietf-netmod-acl-model-19.txt

[<[e-mail]>]

I have reviewed this document as part of the security directorate's
ongoing effort to review all IETF documents being processed by the
IESG. These comments were written primarily for the benefit of the
security area directors. Document editors and WG chairs should treat
these comments just like any other last call comments.

The summary of the review is Ready with issues.

This document defines a YANG data model for ACL. When the term
"ACL" is used in this document it means the sort of ACL that
you might see in firewall rules (e.g., "drop IPv4 traffic with
destination port 21").

*Overall Clarity and Quality*

The document is fairly clear and well written. However, there
is a confusing typo that is listed in the Minor Errors section
of this review.

*Security Analysis*

The Security Considerations section is brief but decent.
However, the last two sentences are unclear and maybe wrong:

   Unauthorized write access to this list can allow intruders
   to access and control the system. Unauthorized read access
   to this list can allow intruders to spoof packets with
   authorized addresses thereby compromising the system.

Which "system" is referred to here? Whatever the answer to
that question, I believe that the main impact of unauthorized
write access to the ACL is that the attacker can modify the
ACL to permit traffic that should not be permitted or deny
traffic that should be permitted. The former may result in
denial of service or compromise of systems on the network.
The latter may result in denial of service. The main impact
of unauthorized read access to the ACL is that the attacker
can determine what ACL rules are in effect and may be able
to use this information to better craft an attack.

*Minor Errors*

Section 3 refers to "action criteria". Every other part of
the specification refers only to "action" or "actions".
My review of the specification indicates that this text
in section 3 should say "actions" not "action criteria".