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Distributed Firewall Policy Validation

Distributed Firewall Policy Validation. by Kyle Wheeler. 1. Introduction Justification Requirements 2. Design Approaches Architecture. 3. Implementation Requirements Graphing Example Policy Example 4. Conclusions. Outline. Security is IMPORTANT. Computer-based attacks are increasing

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Distributed Firewall Policy Validation

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  1. Distributed Firewall Policy Validation by Kyle Wheeler

  2. 1. Introduction Justification Requirements 2. Design Approaches Architecture 3. Implementation Requirements Graphing Example Policy Example 4. Conclusions Outline

  3. Security is IMPORTANT • Computer-based attacks are increasing • Code Red: 2000 hosts/minute (2001) • Slammer: 55 million scans/second (2003) • Attacks are becoming more damaging • CISCO’s IOS code stolen • Valve’s HalfLife 2 code stolen • Trend Micro says: • $13 billion in 2001 • $20 billion in 2002 • $55 billion in 2003 (source)

  4. Security is HARD • Firewalls • Most popular security method • Rules can and do become very complex • Not only method, however • Large networks have: • Many different administrators • Diverse software • Security of large networks requires: • Centralized control • Uniform software • No unified method of verifying security policy implementation • For example, The University of Notre Dame network

  5. Rules for the Solution • Few Requirements • Network-connectivity independent • Mostly system-setup independent • Cannot require root access • Independent of firewall implementations • Flexible Testing • Out-of-order data collection (some support) • Non-uniform distribution of testing nodes • Define a testable security policy language

  6. Analysis Approaches • Static Vulnerability Analysis • Splint • Threat Modeling • Regression Testing

  7. The Good Avoids logical ambiguity Avoids common loopholes and mistakes Easy to understand The Bad Requires detailed knowledge of the implementation Implementation-specific Does not address system interactions Static Vulnerability Analysis

  8. The Good Models entire system Views system as an attacker would Determines vulnerability “surface” The Bad Requires full knowledge of all system details Threat Modeling

  9. The Good Does not need implementation-specific details Easy to understand The Bad Effectiveness is tied to the completeness of the policy Can miss some vulnerabilities Regression Testing

  10. Data Collection Framework • Hierarchical organization • Handles complex networks • Allows asynchronous operation • Wizard • Big picture management, handles policy testing setup • Manager • Organization, Coordination, Retrieval • Prober • Low-level testing, yes/no answers

  11. Managers & Probers • Good Features • Subordinate Managers • Commands can be any length • Key Features • Hierarchical Naming • Maildir-like communication

  12. Hierarchical Naming • Names contain routing information • Names are given or assigned • Network must be laid out intelligently • No auto-discovery • Manually connectable • Must be a root to the tree (base) • Three kinds of sub-names • base.m1.m1.p2.t1.t • Example, slide 17, 12

  13. Maildir-like Algorithm • Benefits • No locks: NFS safe • No partial-files • No new communication server to secure • Two-step file creation • Create in tmp, then move to new • Need unique new name • Use pid and random • Could use more (inode#, for example) • Waiting For Results Requires Polling

  14. Given a complex network… Administrator’s Console Firewall Firewall Prober Manager Prober Manager Firewall Prober Prober Prober Prober Prober Prober Prober Manager Prober Prober

  15. … Handled Nicely Administrator’s Console Firewall Firewall Prober Manager Prober Manager Firewall Prober Manager Prober Prober Prober Prober Prober Prober Prober Prober

  16. Or, More Realistically… 192.168.0.131 192.168.0.131 192.168.0.131 24.11.249.68 internet 129.74.155.226 129.74.152.6 129.74.152.2 172.16.0.16 172.16.0.17

  17. ... Which Can be Organized 192.168.0.130 Wizard & Manager base 129.74.155.226 Manager - base.m1 Prober - base.p3 192.168.0.132 Prober base.p1 192.168.0.131 Prober base.p2 24.11.249.68 Prober base.p4 129.7.152.6 Manager - base.m1.m1 Prober - base.m1.p1 129.74.152.2 Prober base.m1.p2 172.16.0.17 Prober base.m1.m1.p2 172.16.0.16 Prober base.m1.m1.p1

  18. The Implementation • Requirements: • ttcp installed in PATH • Binary connection testing • bash available, in PATH • Written in bash • SSH access, without password • Security issue • Impact can be reduced with careful administration • Graphing with Graphviz

  19. Raw Manager Capability • Hosts, fully connected: • wopr.memoryhole.net • iss.cse.nd.edu • salinan.cse.nd.edu • itisfast.cse.nd.edu • Legend: • Black line = confirmed connection • Dotted line = one side reported connection • Red line = one side reported, one side denied

  20. The Wizard • Interchangeable element • Interprets policy language • Generates and spawns tests • At least three per assertion • Otherwise 50% of all possible • Interprets results of tests • Must have control of “base” Manager

  21. Example Policy network iss 172.16.0.0 255.255.0.0 network nd 127.74.0.0 255.255.0.0 network brk 192.168.0.0 255.255.0.0 brk -> nd brk -> iss via 129.74.152.6 nd -> brk via 24.11.249.168 nd -> iss via 129.74.152.6 iss -X nd iss -X brk 16

  22. Conclusions • Design is feasible • Implementation works as expected • Being generic is hard • Future Work • Investigate long-running “continuous” testing • Policy language needs further flexibility • Speed of testing

  23. Any Questions?

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