Page 84 - DCAP516_COMPUTER_SECURITY

Computer Security

Notes If one silly story will not do the job, let’s try for two with another story from this author’s time
in Dayton, Ohio. At the time an adult movie-house (porn theater) was attempting to reach a
wider audience, so it started showing children’s movies during the day. This author attended the
first showing. While the movie was G rated, unfortunately nobody told the projectionist that the
previews of coming attractions could not be X rated. The result was a lot of surprised parents and
amazed children. There was no second showing for children.

The Biba Integrity Model

The Biba integrity model is similar to the Bell-La Padula model, except that it is designed to
address issues of integrity of data. Security addresses prevention of unauthorized disclosure of
data, integrity addresses unauthorized modification of data. The student should note the
similarities of the two models.

7.5 What is a Trusted Operating System?

Trusted Operating System (TOS) generally refers to an operating system that provides sufficient
support for multilevel security and evidence of correctness to meet a particular set of government
requirements.
The most common set of criteria for trusted operating system design is the Common Criteria
combined with the Security Functional Requirements (SFRs) for Labeled Security Protection
Profile (LSPP) and Mandatory Access Control (MAC). The Common Criteria is the result of a
multi-year effort by the governments of the U.S., Canada, United Kingdom, France, Germany,
the Netherlands and other countries to develop a harmonized security criteria for IT products.

Examples of certified trusted operating systems are:
1. Apple Mac OS X 10.6 (Rated EAL 3+)
2. HP-UX 11i v3 (Rated EAL 4+)
3. Some Linux distributions (Rated up to EAL 4+)
4. Microsoft Windows 7 and Microsoft Server 2008 R2 (Rated EAL 4+ )

5. AIX 5L with PitBull Foundation (Rated EAL 4+)
6. Trusted Solaris
7. Trusted UNICOS 8.0 (Rated B1)

8. XTS-400 (Rated EAL5+)
Examples of operating systems that might be certifiable are:
1. FreeBSD with the TrustedBSD extensions
2. SELinux (see FAQ)
Companies that have created trusted operating systems include:

1. Addamax (BSD, SVR3, SVR4, HP/UX)
2. Argus Systems Group (Solaris, AIX)
3. AT&T (System V)

4. Bull (AIX)
5. Data General (DG/UX)

78 LOVELY PROFESSIONAL UNIVERSITY