1. INSTITUTE FOR CYBER SECURITY 1 The PEI Framework for Application-Centric Security Prof. Ravi Sandhu Executive Director and Endowed Chair Institute for Cyber Security University of Texas at San Antonio May 2009 ravi.sandhu@utsa.edu www.profsandhu.com © Ravi Sandhu PEI = Policy, Enforcement, Implementation

2. INSTITUTE FOR CYBER SECURITY Application Context Our Basic Premise There can be no security without application context Orange Book and Rainbow Series era (1983-1994) Opposite Premise Application context makes high assurance security impossible to achieve  May need to settle for “reasonable” assurance or “good- enough” security  Its about “mission assurance” not “information assurance” © Ravi Sandhu2

3. INSTITUTE FOR CYBER SECURITY Rainbow Series 34 titles listed in Wikipedia as the “most significant Rainbow series books” Only 1 addresses applications  Trusted Database Interpretation (TDI)  Scope: “Trusted Applications in general and database management system in particular” © Ravi Sandhu3

4. INSTITUTE FOR CYBER SECURITY Application Context Software- ArchitectProject% TimeLabel AliceVista25%U AliceSecureVista75%S BobXP100%U What precisely is Secret?  There exists a SecureVista project  Alice works on SecureVista  Alice’s effort on SecureVista is 75%  All or some of the above How do we maintain integrity of the database?  Depends © Ravi Sandhu4 Much work and $$$ by researchers and vendors, late 80’s-early 90’s

5. INSTITUTE FOR CYBER SECURITY Orange/Rainbow Fatal Flaws Enforcement of 1-way information flow in a lattice is not the dominant concern for most applications Avoiding covert channels is not the highest priority for most applications Exclusion of cryptography is not a smart decision for securing distributed systems © Ravi Sandhu5 The Common Criteria, an ISO standard, and successor to the Orange Book has its own problems

6. INSTITUTE FOR CYBER SECURITY Post-Orange Era Firewalls, patch cycle, vulnerability scanners, intrusion detection, intrusion prevention, Identity Management, Federation, SSL, VPNs, PKI, etc Emergence and dominance of RBAC over MAC and DAC Emergence of highly motivated, sophisticated and innovative attackers © Ravi Sandhu6

7. INSTITUTE FOR CYBER SECURITY Emerging Application-Centric Era (ACE) © Ravi Sandhu7 ECE Enterprise-Centric Era (Orange/Rainbow Era Post-Orange Era) ACE Application-Centric Era Applications are cyber analogs of previously existing enterprise-centric applications on-line banking brokerage e-retail auctions search engines Future applications will be fundamentally different ?

8. INSTITUTE FOR CYBER SECURITY ACE Characteristics Multi-party interests Fuzzy security objectives Attack/threat models © Ravi Sandhu8

9. INSTITUTE FOR CYBER SECURITY PEI Models: 3 Layers/5 Layers © Ravi Sandhu9

10. INSTITUTE FOR CYBER SECURITY Secure Information Sharing (SIS) A fundamental problem in cyber security – Share but protect Current approaches not satisfactory Classic models (DAC/MAC/RBAC) do not work Recent approaches Proprietary systems for Enterprise Rights Management Many solutions: IBM, CA, Oracle, Sun, Authentica, etc. Interoperability is a major issue Many languages have been standardized XrML, ODRL, XACML, etc. Primarily, dissemination or object centric © Ravi Sandhu10

11. INSTITUTE FOR CYBER SECURITY Dissemination Centric Sharing Attach attributes and policies to objects  Objects are associated with sticky policies  XrML, ODRL, XACML, etc. provide sticky policies AliceBobCharlieRaviShashi Attribute + Policy Cloud Object Attribute + Policy Cloud Object Attribute + Policy Cloud Object Attribute + Policy Cloud Object Dissemination Chain with Sticky Policies on Objects Attribute Cloud © Ravi Sandhu11

12. INSTITUTE FOR CYBER SECURITY Group Centric Sharing (g-SIS) Advocates bringing users & objects together in a group  In practice, co-exists with dissemination centric sharing Never Group Subject Leave Current Group Subject Past Group Subject Join Never Group Object Remove Current Group Object Past Group Object Add Two useful metaphors – Secure Meeting/Document Room Users’ access may depend on their participation period E.g. Program committee meeting, Collaborative Product Development, Merger and Acquisition, etc. – Subscription Model Access to content may depend on when the subscription began E.g. Magazine Subscription, Secure Multicast, etc. © Ravi Sandhu12

13. INSTITUTE FOR CYBER SECURITY Core g-SIS Properties JoinAdd Authz AddJoin Authz 1. Provenance: Authorization can only originate during a simultaneous period of membership 2. Bounded Authorization: Authorization cannot grow during non- membership periods 3. Persistence: Authorization cannot change if no group event occurs

14. INSTITUTE FOR CYBER SECURITY g-SIS Operation Semantics 14 GROUP Authz (S,O,R)? Join Leave Add Remove Subjects Objects GROUP Authz (S,O,R)? Strict Join Strict Leave Liberal Add Liberal Remove Liberal Join Liberal Leave Strict Add Strict Remove Subjects Objects © Ravi Sandhu14

15. INSTITUTE FOR CYBER SECURITY Operation Semantics (Continued) Strict Join (SJ): Only access objects added after Join time Liberal Join (LJ): Also access objects added before Join time Strict Leave (SL): Lose access to all objects Liberal Leave (LL): Retain authorizations held at Leave time © Ravi Sandhu15

16. INSTITUTE FOR CYBER SECURITY Operation Semantics (Continued) 16 Strict Add (SA): Only accessible by existing subjects Liberal Add (LA): No such restrictions Strict Remove (SR): All subjects lose access Liberal Remove (LR): Subjects who had authorization at Remove time can retain access

17. INSTITUTE FOR CYBER SECURITY Family of g-SIS Models 17 Most Restrictive g-SIS Specification: Traditional Groups: Secure Multicast:

18. INSTITUTE FOR CYBER SECURITY PEI Models: 3 Layers/5 Layers © Ravi Sandhu18

19. INSTITUTE FOR CYBER SECURITY Concept of Stale-Safety AIP ADP AEP AIP: Authorization Information Point Update ADP: Authorization Decision Point AEP: Authorization Enforcement Point © Ravi Sandhu19

20. INSTITUTE FOR CYBER SECURITY g-SIS Enforcement Architecture/Models Allows offline access Assumes a Trusted Reference Monitor (TRM)  Resides on group subject’s access machine  Enforces group policy  Synchronizes attributes periodically with server Objects available via Super-Distribution  Encrypt once, read wherever authorized © Ravi Sandhu20

21. INSTITUTE FOR CYBER SECURITY g-SIS Never Group Subject Current Group Subject Past Group Subject Join Add Join Never Group Object Current Group Object Past Group Object Add Remove Leave Time of Join NULL Join-TS Leave-TS Time of Join Time of Leave Time of Add NULL Add-TS Remove-TS Time of Add Time of Remove Authz (s,o,r) Add-TS(o) > Join-TS(s) & Leave-TS(s) = NULL & Remove-TS(o) = NULL Subject Attributes Object Attributes © Ravi Sandhu21

22. INSTITUTE FOR CYBER SECURITY g-SIS Architecture CC GA Group Subjects TR M … 1. Read Objects 5.1 Request Refresh 5.2 Update Attributes 3.1 Subject Leave (s) 4.1 Object Remove (o) 3.2 Set Leave-TS (s) 4.2 Add o to ORL CC: Control Center GA: Group Administrator Subject Attributes: {id, Join-TS, Leave- TS, ORL, gKey} ORL: Object Revocation List gKey: Group Key Object Attributes: {id, Add- TS} Refresh Time (RT): TRM contacts CC to update attributes © Ravi Sandhu22

23. INSTITUTE FOR CYBER SECURITY Staleness in g-SIS RT 0 RT 1 RT 2 RT 3 Join (s) Add (o1) Add (o2) Leave (s) Request (s, o1, r) Request (s, o2, r) Authz (s,o,r) Add-TS(o) > Join-TS(s) & Leave-TS(s) = NULL & o NotIn ORL Was authorized at recent RT Was never authorized RT: Refresh Time RT 4 © Ravi Sandhu23

24. INSTITUTE FOR CYBER SECURITY Stale-Safe Security Properties Weak Stale-Safety  Allows (safe) authorization decision to made without contacting the CC  Achieved by requiring that authorization was TRUE at the most recent refresh time Strong Stale-Safety  Need to obtain up to date authorization information from CC after a request is received  If CC is not available decision cannot be made 24

25. INSTITUTE FOR CYBER SECURITY Properties RTPerform Stale-unsafe Decision RequestPerform Request Perform Weak Stale-Safety: Strong Stale-Safety: 25 Formula JoinAdd Authz

26. INSTITUTE FOR CYBER SECURITY Conclusion Security tools for a brave new world ACE PEI UCON © Ravi Sandhu26