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DIVERSYS DIVErse Rejuvenation SYStem

DIVERSYS DIVErse Rejuvenation SYStem. Miguel Garcia , Nuno Neves and Alysson Bessani. Faculdade de Ciências - Universidade de Lisboa. Outline. Motivation Replication Diversity Recovery DIVERSYS Conclusions Limitations Future work. Motivation.

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DIVERSYS DIVErse Rejuvenation SYStem

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  1. DIVERSYSDIVErse Rejuvenation SYStem Miguel Garcia, NunoNeves and AlyssonBessani Faculdade de Ciências - Universidade de Lisboa

  2. Outline • Motivation • Replication • Diversity • Recovery • DIVERSYS • Conclusions • Limitations • Future work Miguel Garcia

  3. Motivation Softwareverification and validation is extremely hard and expensive Everysoftware has bugs or vulnerabilities when comprises security When vulnerabilities are exploited, the system can behave abnormally AVI model: attack + vulnerability→ intrusion→ fault Miguel Garcia

  4. Motivation So…we need to live with vulnerabilities and faults. If we cannot defeat or prevent them we must tolerate intrusions. How? Replication is the key to build intrusion-tolerant systems Miguel Garcia

  5. ReplicationIntrusion-tolerant systems Internet Miguel Garcia

  6. Diversity System without diversity ExploitA OS k System compromised ExploitA OS k ExploitA OS k ExploitA OS k Miguel Garcia

  7. Diversity System with diversity ExploitC OS k System compromised OS y ExploitB OS z OS i Miguel Garcia

  8. Diversity • They play a important part in replicated systems • There are plenty of opportunities available • A substantial part of the code of a replica is the OS • People will resort to an OS rather than build their own Why operating systems? Miguel Garcia

  9. Rejuvenations OS recycling Exploit X:1 Patch X:1 Discovery X:1 time Detect Intrusion X:1 RecoveryNew life cycle for Y:1 new life cycle for X:2 Hard problem Miguel Garcia

  10. DIVERSYS and related work • Manages OS diversity [Roeder10] and recoveries [Castro02,Sousa10] • For intrusion-tolerant systems [Sousa10] [Castro02,Sousa10,Roeder10] make strongtimeassumptions. Miguel Garcia

  11. DIVERSYS • Weak time assumptions • Configurable based on the criticality • Self-maintained • Maximize diversity • Develop a new recovery manager that models better the system’s risk Goals: Miguel Garcia

  12. DIVERSYS Risk level • We developed a metric to evaluate the system risk, the Risk level. • Each OS has a risk level which increases over the time (degradation time). • Every OScontributes to the system’s Risk level. • If some IDS or BFT protocol detects abnormalbehavior, DIVERSYS increases the Risk level. • When the Risk level reachesα,DIVERSYS triggers a recovery. And the Risk level decreases. Miguel Garcia

  13. Risk level R1 recovery R2 recovery R3 α R2 Risk R1 R0 0 time Risk level Miguel Garcia

  14. Risk level • To calculate the Risk level we need data that correlates every different OS. • Based on the idea that diversity is good DIVERSYS selects OSes by their commonality value, i.e., their common vulnerabilities (CV) [Garcia11]. • The Risk level is bigger for OS pairs with more CV. Miguel Garcia

  15. Risk level α= -15 Recovery, Windows2008 left, Windows2003 join. Miguel Garcia

  16. DIVERSYS architecture OS pool safe Hyp0 Hyp1 Hyp … Hyp n-1 Risk level Risk level Risk level Risk level unsafe Replica 0 Replica 1 Replica … Replica n-1 Internet Miguel Garcia

  17. Conclusions • DIVERSYS is a management application for OS diversity. • Selects operating systems maximizing the diversity in order to avoid common failures. • Performs recoveries based on a metric: Risk level. Miguel Garcia

  18. Limitations • The data that feeds DIVERSYS needs to be prepared, refined and updated. • Since the number of OSes (distributions, versions) is finite, we assume that eventually a patch is available to update vulnerable OSes. • Find vulnerability life-cycle data. Miguel Garcia

  19. Future work • Gather vulnerability and patch data automatically into DIVERSYS. • Apply those patches automatically in the DIVERSYS OS pool. • Validate and refine the Risk level metric, in order to give more confidence. Probably using more parameters from OSes. Miguel Garcia

  20. Questions? mhenriques@lasige.di.fc.ul.pt Miguel Garcia

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