1 Group-Centric Models for Secure and Agile Information Sharing Ravi Sandhu Executive Director and Endowed Professor April Joint work with ICS colleagues Ram Krishnan, Jianwei Niu and Will Winsborough © Ravi Sandhu World-Leading Research with Real-World Impact! Institute for Cyber Security

2 Application Context  Basic premise  There is no security without application context  Opposite premise  Orange Book and Rainbow Series Era ( )  Application context makes high-assurance impossible o Good-enough security is good enough o Mission-assurance not information-assurance  Towards the end of this era applications had to be addressed: Trusted Database Interpretation (TDI)  Firewall Era ( )  Perimeter security, vulnerability scanning, penetrate and patch, intrusion prevention, secure coding, etc © Ravi Sandhu World-Leading Research with Real-World Impact!

3 Application Context  What precisely is Secret?  There exists a SecureWin7 project  Alice works on SecureWin7  Alice’s effort on SecureWin7 is 75%  All or some of the above  How do we maintain integrity of the database  Depends Data and security model are intertwined Much work and $$$ by researchers and vendors, late 80’s-early 90’s Software ArchitectProject% TimeLabel AliceWin725%U AliceSecureWin775%S BobVista100%U © Ravi Sandhu World-Leading Research with Real-World Impact!

4 Application Centric Security  Modern applications  Multi-party  Different objectives and responsibilities, often in conflict  Ongoing projects at ICS  Secure information sharing  Social networking  Critical infrastructure assurance  SaaS in the Cloud/Intercloud  Smart grid  New ACM Conference on Data and Application Security and Privacy (CODASPY)  Feb 21-23, 2011, San Antonio, Texas   Papers due: Sept 15 th 2010 © Ravi Sandhu World-Leading Research with Real-World Impact! The future is application centricThe future is data and application centric

5 PEI Models Security and system goals (objectives/policy) Policy models Enforcement models Implementation models Necessarily informal Specified using users, subjects, objects, admins, labels, roles, groups, etc. in an ideal setting. Security analysis (objectives, properties, etc.). Approximated policy realized using system architecture with trusted servers, protocols, etc. Enforcement level security analysis (e.g. stale information due to network latency, protocol proofs, etc.). Technologies such as Cloud Computing, Trusted Computing, etc. Implementation level security analysis (e.g. vulnerability analysis, penetration testing, etc.) Software and Hardware Concrete System © Ravi Sandhu World-Leading Research with Real-World Impact!

6 Secure Information Sharing (SIS) Goal: Share but protect  Containment challenge  Client containment  High assurance infeasible (e.g., cannot close the analog hole)  Low to medium assurance achievable  Server containment  Will typically have higher assurance than client containment  Policy challenge  How to construct meaningful, usable SIS policy  How to develop an intertwined information and security model © Ravi Sandhu World-Leading Research with Real-World Impact!

7 SIS Policy Construction  Dissemination Centric (d-SIS)  Sticky policies that follow an object along a dissemination chain (possibly modified at each step)  Group Centric (g-SIS)  Bring users and information together to share existing information and create new information  Metaphors: Secure meeting room, Subscription service  Benefits: analogous to RBAC over DAC  Why not use existing access control (AC) models?  Discretionary (DAC): fails containment  Lattice-based (LBAC or MAC): no agility  Role-based (RBAC): too general  Attribute-based (ABAC): too general © Ravi Sandhu World-Leading Research with Real-World Impact!

8 g-SIS Model Components  Operational aspects  Group operation semantics o Add, Join, Leave, Remove, etc o Multicast group is one example  Object model o Read-only o Read-Write (no versioning vs versioning)  User-subject model o Read-only Vs read-write  Policy specification  Administrative aspects  Authorization to create group, user join/leave, object add/remove, etc. © Ravi Sandhu World-Leading Research with Real-World Impact! Users Objects Group Authz (u,o,r)? join leave add remove

9 g-SIS Models  Isolated groups model  No subject level info flow between groups  Groups are information sinks  Connected groups model  Connected groups with some type of relationship o E.g. Subordination (read, write, create subject, move subject), conditional membership, mutual exclusion, etc.  Subject level info flow governed by relationship semantics Isolated Connected Isolated + ABAC Connected + ABAC g-SIS Models Anticipate to be straight-forward Work in Progress © Ravi Sandhu World-Leading Research with Real-World Impact!

10 Isolated Group Model (g-SIS i )  Abstract model specification = Stateless (vis-à-vis Stateful)  Specify without worrying about state structure o No data structure to maintain user/object attributes  Use many sorted, first-order linear temporal logic (FOTL) o FOTL = LTL with parameters, constants, variables and quantifiers  Entities in the isolated group model  Users, subjects, object versions, groups and permissions  Operations in the isolated group model  User membership operations o Join(u,g), Leave(u,g)  Object membership operations o Add(o,v,g), Remove(o,v,g) o CreateO(o,v,g)  Subject operations o createS(u,s,g), killS(u,s,g), read(s,o,v,g), update(s,o,v1,v2,g)  Authorization to exercise a permission p on an object version  Authz(u,o,v,g,p)  AuthzS(s,o,v,g,p) © Ravi Sandhu World-Leading Research with Real-World Impact! CreateO(o,v init,g) update (s,o,v init,v 1,g) update (s,o,v init,v 2,g) update (s,o,v 1,v4,g) update (s,o,v 1,v 3,g)

11 g-SIS i Operation Semantics GROUP Authz (u,o,r)? Strict Join Strict Leave Liberal Add Liberal Remove Liberal Join Liberal Leave Strict Add Strict Remove Users Objects Strict Create Liberal Create update Read-only Model Read-Write Model GROUP Authz (u,o,r)? Join Leave Add Remove Users Objects Create update © Ravi Sandhu World-Leading Research with Real-World Impact!

12 Core Properties  Authorization Persistence  Authorization cannot change unless some group event occurs © Ravi Sandhu World-Leading Research with Real-World Impact!

13 Core Properties (contd)  Authorization Provenance  Authorization can begin to hold only after a simultaneous period of user and object version membership  Bounded Authorization  Authorization cannot grow during non-membership period © Ravi Sandhu World-Leading Research with Real-World Impact!

14 Core Properties (contd)  Version Authorization Uniformity  A current user should be authorized to read and write either all versions of locally created objects or none of them © Ravi Sandhu World-Leading Research with Real-World Impact!

15 g-SIS i Specification  A g-SIS specification specifies the precise conditions under which Authz(u,o,v,g,p) and AuthzS (s,o,v,g,p) may hold  A g-SIS specification must satisfy all of the core properties  That is: © Ravi Sandhu World-Leading Research with Real-World Impact!

16 Membership Semantics  Strict Vs Liberal operations  User operations:,  Object operations:, and u not authorized to access objects added prior to join time Users joining after add time not authorized to access o u retains access to objects authorized at leave time Users authorized to access o at remove time retain access © Ravi Sandhu World-Leading Research with Real-World Impact!

17 Membership Renewal Semantics  Lossless Vs Lossy Join  Lossless: Authorization from past membership not lost  Lossy: Some authorization lost at re-join time  Restorative Vs Non-Restorative Join  Restorative: Authorizations from past membership restored  Non-Restorative: Past authorizations not restored on re-join  Gainless Vs Gainful Leave  Restorative Vs Non-Restorative Leave © Ravi Sandhu World-Leading Research with Real-World Impact!

18 The π-system Specification  Allows any variation of membership semantics  Strict and Liberal versions of user and object operations  Allows selected membership renewal semantics  Lossless and Non-Restorative Join  Gainless and Non-Restorative Leave © Ravi Sandhu World-Leading Research with Real-World Impact!

19 The π-system Specification (contd) © Ravi Sandhu World-Leading Research with Real-World Impact!

20 The π-system Specification (contd) © Ravi Sandhu World-Leading Research with Real-World Impact!

21 Formal Analysis  The core properties are mutually independent  The core properties are consistent  The π-system satisfies the core properties  Used a model checker to prove these results for a small carrier case  Extended this result using manual proof for large carrier case © Ravi Sandhu World-Leading Research with Real-World Impact!

22 Connected Groups Model (g-SIS c )  Groups connected by some type of relationship  Conditional membership (users/objects)  Subordination o Read, write, subject create, subject move  Mutual exclusion  Cardinality  Relationships are reflexive by definition  Transitivity and anti-symmetry must be explicitly defined if needed  Relationships vary over time in SIS scenario G2G3 G1 G5G6 G4 condM subordR subordC subordM condM subordW © Ravi Sandhu World-Leading Research with Real-World Impact!

23 Configuring Classic Policies  LBAC in g-SIS c A sample lattice Equivalent g-SIS c Configuration © Ravi Sandhu World-Leading Research with Real-World Impact! Not an equivalent g-SIS c configuration (trusted pipeline from G_ L to G_H via G_M1 or G_M2)

24 Configuring Classic Policies (contd)  Domain and Type Enforcement (DTE) in g-SIS DTE for trusted pipeline from L to H via M1 or M2 Equivalent g-SIS c Configuration Objects Subjects © Ravi Sandhu World-Leading Research with Real-World Impact! LBAC in DTE A sample lattice subor dW

25 LBAC Inadequate for Agile Sharing  What if H users from Org A and S users from Org B want to collaborate on a mission?  What if Org B does not want H users to create subjects in S and write to S objects? o E.g. Org B wants to share intel with Org A but do not want them to modify their data o Categories work only if pre-determined Org AOrg B subordR Org AOrg B LBACg-SIS C © Ravi Sandhu World-Leading Research with Real-World Impact! subordR

26 LBAC Inadequate (contd) subordC subordR subordW subordC subordR subordW subordC subordR subordW TS S G1 G2 H L condM Export subordR Export allowed only by Trusted Subjects SJ/LJ, SL/LL SA/LA, SR/LR SJ/LJ, SL/LL SA/LA, SR/LR Export allowed only by Trusted Subjects SJ/LJ, SL/LL SA/LA, SR/LR SJ/LJ, SL/LL SA/LA, SR/LR SC/LC Publish group for TS objects Publish group for S objects © Ravi Sandhu World-Leading Research with Real-World Impact! Can use all isolated group operation semantics

27 Conclusion  No security without application context  Group-Centric Secure Information Sharing is a promising approach  Still in early days  We project the need for Application Centric security models in many emerging arenas  Goal: have a methodology and conceptual framework for this purpose  PEI, Stateless-Statefull specifications, Stale-safe enforcement, etc © Ravi Sandhu World-Leading Research with Real-World Impact!