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NFV Attestation Survey. Xitao Wen. Attestation Architecture. Excerpted from [1] “Principles of remote attestation” in International Journal of Information Security, 10(2):63–81, 2011. Chain of Trust. Trusted booting: TPM -> BIOS -> Boot Loader -> OS
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NFV Attestation Survey Xitao Wen
Attestation Architecture Excerpted from [1] “Principles of remote attestation” in International Journal of Information Security, 10(2):63–81, 2011.
Chain of Trust • Trusted booting: TPM -> BIOS -> Boot Loader -> OS • Former entity measures the integrity of binary and config of latter entity, and sign the hash in a certificate • A sequence of certificates are provided to appraiser as evidence of system integrity • Appraiser verifies hashes with a list of trustworthy implementations/configs
Trust Base • Service • Endorsement key • Memory curtaining • Data sealing • Implementation • Hardware: Trust Platform Module (TPM), measurement hardware • Software: Secure kernel, secure hypervisor
Attestation Service Provider (ASP) 1. Most based on code execution Attestation • BIND [2]: critical code only; bind data/code integrety • Pioneer [3]: no hardware trust base • Schellekens et al. [4]: use TPM for fewer constraints • Nexus [5]: hypervisor-style seperation • Three categories • Integrity attestation (earliest) • Property-based Attestation • Behavior-based Attestation [17] 2. Specific Purpose Attestation • CoPilot [6] • Gu et al. [7]
Property-based Attestation (PBA) • ASP signs properties rather than binary hashes • How to Determining Properties? • Delegation [12][13][14]: delegate hash-property mapping to a trusted third party • Behavior control [15][20][18]: behavior-based access control or measurement • Code analysis [11][16]: semantic code analysis • Extend trust chain to verify the trustworthiness of property measurement • Enhanced boot loader [19]
PBA – Behavior Control • Attest the behavior of security policies • Usage control policy model [15] • Dynamic OS properties [18] • Verify security policies based on behavior modeling • Enforcement mechanism also needs attestation
PBA – Code Analysis • [11] extends Java VM to conduct byte-code analysis and attestation • [16] proposes attest properties via proof-carrying code
Attestation in NFV, Cloud and Virtual Networks All workshop papers, no real implementations, just high-level ideas • Verifiable NFO [8] • Framework to verify functionality, performance and accounting for NFV • Very high-level roadmap • TCCP [9] • Framework to ensure confidentiality and integrity of computation in cloud • Depends on trusted VM monitor and trusted coordinator • Simply apply attestation to cloud environment • Accountability in hosted virtual network [10] • Account software integrity and functionality • Two approaches • Violation detection with measurement • Verify software integrity with attestation SDN/NFV Verification has some work on policy correctness [21-31]
Uniqueness in NFV/SDN Environment • Network policies + network functions • Service composition/chaining • Multiple distributed VNFs
Properties to Attest in NFV/SDN • Correctness of NFV functionality [21][22] • Policy correctness and enforcement • Guaranteed traversal for packets • Correct order of service chains • Virtual Network Function (VNF) state consistency • Intra-VNF property • Inter-VNF property [32] • VNF version compatibility in a service chain • Performance monitoring (throughput, latency) • Resource accounting (memory, bw, CPU cycles) • Traffic confidentiality (seems impossible to prevent…)
Potential Topics • For the unique properties, what info and system support are needed? • SDN policy, controller, OS, network traffic, NFV software • Two levels: read / write • Focus more on systems than PL. • What verification/attestation tools can be used? (Bo) • What NFV code can be used? (Bo) • Load balancer, security middleboxes, cache, TCP performance enhancer/acceleration, Web Content Optimization (WCO)
NFV/SDN Attestation Architecture Attestation Procedure: 0. Trust establishment 1. Attestation request 2. Measurement setup 3. Measurement collection 4. Attestation report SDN Controller 1. Attestation request Trusted Delegate 4. Attestation report Client attester 3. Measurement collection 2. Measurement setup Internet Client network Data path Trusted measurement points Control path SDN switch Secure attestation channel
Trusted Measurement Points • VNF monitoring module in VM hypervisor • Check VNF binary/config before launching • Monitor runtime config change • Measure flow and utility statistics • Process FlowTag [34] • Trusted module in SDN switch agent or SDN controller • Take snapshot of rules • Setup rules for measurement tasks • Data-plane logging/injection points • Insert testing packets • Log trajectory and timestamp of testing packets
Per-property Verification Technique • VNF correctness (use existing tech) • Attest binary/config of VNF • Verify functionality of binary/config offline • Policy correctness • Conduct incremental header space analysis on flow table snapshot (use existing tech) • Inject test traces to test data-plane behavior • Rule property • Order, priority -> test explosion problem! • Dependency graph for rescue? • Incremental testing, depends on # of sub-space? • VNF state consistency • Asymmetric routing lead to inconsistent forwarding for a security VNF • Strong/eventual consistency • Fast and efficient attestation/detection of such problem • Formulate as certain version of model checking? State machine inference?
Per-property Verification Technique • Version compatibility • Combine VNF version with external compatibility information • Checked by trusted delegate • Performance monitoring • Latency: time sample packet at NFV hypervisor • Throughput: measured by hypervisor • Resource accounting • Depend on trusted hypervisor module • Traffic confidentiality • In network: encryption? • On NFV: Terra [35]?
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