SUMMARY
C2 refers to a set of security policies that define how a secure system
operates. The C2 evaluation process is separate from the C2 certification
process. As of August 1995, National Security Agency (NSA) granted the C2
security rating for Windows NT Server and Workstation version 3.5. As a
result these operating systems are on the Evaluated Products List (EPL).
Windows NT Server and Workstation version 3.51 has been granted the
security rating of E3/F-C2 though a similar evaluation process in the UK.
For security evaluation for Windows 2000 and beyond, see the following Microsoft Web site:
NOTE: This does not mean that Windows NT is C2 certified (no operating system is ever C2 certified). Certification applies to a particular installation, including hardware, software, and the environment that the system is in. It is up to an individual site to become C2 certified.
MORE INFORMATION
The requirements for A-, B-, C-, and D-level secure products are outlined
in the Trusted Computer System Evaluation Criteria (TCSEC) published by the
National Computer Security Center (NCSC). This publication is referred to
as the "Orange Book," and is part of NSA's security "rainbow series."
Security level requirements are open to interpretations that change over
time. When undergoing evaluation, each vendor negotiates with the NSA about
whether or not the details of its particular system implementation conform
with the abstract security policy concepts in the NSA's books. The vendor
must provide evidence that the requirements are being met.
Microsoft has opted not to include certain components of Windows NT in the
evaluation process, not because they would not pass the evaluation, but to
save time by reducing the load on the NSA. Additionally, the MS-DOS/Windows
on Windows (WOW) system may be treated as a Win32 application and would
therefore not need to be evaluated as part of the Trusted Computer Base
(TCB). Networking on NT may not have to go through the "Red Book," or
"Trusted Network Interpretation." It may be enough to consider networking
to be another subsystem, and therefore only the Orange Book would apply.
New or modified components and other hardware platforms can go through a
"RAMP" process to be included in the evaluation at a later time.
C2 Overview
The security policy in C2 is known as Discretionary Access Control (DAC).
In the Windows NT implementation, the basic idea is that users of the
system:
- Own objects
- Have control over the protection of the objects they own
- Are accountable for all their access-related actions
C2 classification does not define a substantive security system in the
sense of classified or unclassified data. (B-level security assumes the
existence of an independent security classification system and enforces
that system, but does not specify the substance of the classification
system.)
For example, in Windows NT, every object (file, Clipboard, window, and so
on) has an owner; any owner can give or not give other users access to its
objects. The system tracks (audits) your actions for the administrators
(that is, the system administrator can track the objects you accessed, both
successes and failures).
The key distinction between C-level and B-level security is in the notion
of access control. In a C2 (DAC) system, owners have absolute discretion
about whether or not others have access to their objects. In a B-level, or
Mandatory Access Control (MAC) system, objects have a security level
defined independently from the owner's discretion. For example, if you
receive a copy of an object marketed "secret," you can't give permission to
other users to see this object unless they have "secret" clearance. This is
defined by the system independent of your discretion. MAC involves the
concept of "data labeling," which is the creation and maintenance by the
system of security "labels" on data objects, unalterable by users (except
in certain cases under system control and auditing). An administrator can
get access to anyone's objects, although it may require some programming to
do so (that is, the user interface won't expose this power).
You can obtain more information on this process, including frequently asked
questions, a copy of the evaluated products list, and copies of TCSEC and
other documentation, visit the following NCSC Web site:
Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.