1. ECE-8843 http://www.csc.gatech.edu/copeland/jac/8843/ Prof. John A. Copeland john.copeland@ece.gatech.edu 404 894-5177 fax 404 894-0035 Office: GCATT Bldg 579 email or call for office visit, or call Kathy Cheek, 404 894-5696 Chapter 10b - Trusted Systems

2. 2 Trusted Systems Subject: - an entity capable of accessing objects. Usually a process of an application being run by a user. Note that a secure user authentication procedure is essential (pass-phase, biometrics,...). Object: - anything to which access is controlled. This includes files, portions of files, programs, segments of memory, records and fields of records in a database. Access Right: - a way in which an object can be accessed by a subject, typically read, write, and execute. Access matrix, access control list (ACL), or capability list (ticket): ways of defining access rights.

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6. 6 Multilevel Security No Read Up (Simple Security Property): - a subject can only read an object of less or equal security level. No write down (*-Property): - a subject can only write to an object of greater or equal security level (can not lower the security classification of information by writing to an object with a lower security level). You can contribute information to a higher security level report, but can not read the report. Need to Know - a subject can only access data if he is cleared for that project or category (compartmentalized sensitive information). [not in book] Reference Monitor: - a way to enforce the rules above....* Top-Secret Secret Confidential Unclassified * so secret we can’t reveal the name.

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8. 8 Alice’s program has a Trojan Horse hidden inside.

9. 9 When Bob runs Alice’s program, the Trojan writes info from Bob’s Secret file to Alice’s Confidential file (“write down”).

10. 10 Alice’s Program has to access the Secret Program through the Reference Monitor, which upgrades the level of the process to Secret. Secret Clearance Confidential Clearance

11. 11 The Security Monitor will not let the (now rated Secret) process write down to a lower level file.

12. The Computer Security Center within the National Security Agency has a Commercial Product Evaluation Program To be rated a “Trusted System” (at a certain level) and be eligible for government and DoD RFP’s, the computer must provide: Complete Mediation: Security rules are enforced on every access, not just when a file is opened. Isolation: The reference monitor and database are protected from unauthorized modification. Verifiability: The reference monitor’s correctness must be mathematically provable (that it can provide Complete Mediation and Isolation). 12

14. In January 1996, the United States, United Kingdom, Germany, France, Canada, and the Netherlands released a jointly developed evaluation standard for a multi- national marketplace. This standard is known as the "Common Criteria for Information Technology Security Evaluation" (CCITSE) usually referred to as the "Common Criteria" (CC). The Common Criteria can be used for the following purposes: (see table on next slide) Under the Common Criteria, each level of trust rating from the TCSEC can be specified as a Protection Profile (PP). A Protection Profile looks very similar to a level of trust rating but has two fundamental differences. First, where the TCSEC binds sets of features and assurances together, the Common Criteria allows Protection Profiles to combine features and assurances together in any combination. Also, the TCSEC specifies a fixed set of ratings (profiles), but the Common Criteria allows for consumers to write a customized set of requirements in a standard format. The TPEP office is currently developing Protection Profiles that map to the C2 rating referred to in the TCSEC and SBU Firewall Protection Profiles. Common Criteria evaluations are now in progress using the Firewall Protection Profiles. http://www.radium.ncsc.mil/tpep/library/ccitse/cc_over.html “Common Criteria” Security Specifications