Computer Science Cloud Computing Infrastructure Security Peng Ning With Ahmed Azab, Xiaolan Zhang, Wu Zhou, Xuxian Jiang, and Zhi Wang. June 29, 2012 1 ACNS 2012 Supported by the US NSF under grant # 0910767, the US ARO under the grant # W911NF-08-1-0105, and IBM under Open Collaboration Research (OCR) Awards.
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Computer Science Cloud Computing Infrastructure Security Peng Ning With Ahmed Azab, Xiaolan Zhang, Wu Zhou, Xuxian Jiang, and Zhi Wang. June 29, 20121ACNS.
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ACNS 2012 1
Computer Science
Cloud Computing Infrastructure Security
Peng Ning
With Ahmed Azab, Xiaolan Zhang, Wu Zhou, Xuxian Jiang, and Zhi Wang.
June 29, 2012
Supported by the US NSF under grant # 0910767, the US ARO under the grant # W911NF-08-1-0105, and IBM under Open Collaboration Research (OCR) Awards.
Computer Science ACNS 2012 2
Outline
• Background• Security threats to cloud computing• Security of cloud computing infrastructure
– Driven by a new security architecture for cloud computing– Hypervisor-based security services– Offline VM image security services– Hypervisor integrity services– Isolation that can bypass hypervisor control
• Conclusion
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Computer Science ACNS 2012 3
What is Cloud Computing
• Wikipedia– Cloud computing is a paradigm of computing in which
dynamically scalable and often virtualized resources are provided as a service over the Internet
– Users need not have knowledge of, expertise in, or control over the technology infrastructure in the "cloud" that supports them
– Reduction in hardware, operational and administrative costs
• Virtualization is a key to cloud computing– Scalability– Ease of use– Affordable pricing
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Computer Science ACNS 2012 4
Example: Amazon Elastic Compute Cloud (EC2)
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EC 2 Management ConsoleStart an InstanceSet up the InstanceLaunch the InstanceVerify the Instance
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Security Threats in Cloud Computing
External threats
Guest-to-guest threats
Guest-to-cloud threats
Cloud-to-guest threats
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Cloud Computing Infrastructure Security
• Our proposal – A security architecture for compute clouds
• Focus on Infrastructure as a Service (IaaS)
– Addition of security architecture components• Hypervisor-based security services• Offline VM image security services• Hypervisor integrity services• Isolation mechanisms that can bypass the hypervisor
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A Typical Compute Cloud
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Virtualization-based Runtime Security Services
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HIMA [ACSAC ’09]HookSafe [CCS ’09]
Computer Science ACNS 2012
Example Service: HIMA
• HIMA: Hypervisor based Integrity Measurement Agent
• Validation of VMs with runtime guarantees– Measure the VM OS and applications loaded into guest VMs– Actively monitor all guest events that could change measured
applications• Time of Check to Time of Use (TOCTTOU) consistency
• Prototypes– Initial implementation works for Xen (para-virtualization)– Ported to support KVM (hardware assisted virtualization)
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Ahmed M. Azab, Peng Ning, Emre C. Sezer, and Xiaolan Zhang, "HIMA: A Hypervisor Based Integrity Measurement Agent," in Proceedings of ACSAC 2009, December 2009.
Example Service: Nüwa(女娲)• Nüwa – Offline Patching of VM Images• Motivation
– Dormant VM images usually contain vulnerabilities– Offline patching service
• A desirable security service in compute clouds
• Technical challenge– Current patching system: Designed for running systems– Pre- and post-processing scripts– Examples: Stop/start daemons; Conditional updates
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Computer Science ACNS 2012 12
Nüwa Approach
• Two phases– Phase 1: Automatic script rewriting – Phase 2 (Leftovers): Resort to online updates– Our research focus is on script rewriting
• Variations– Standalone Nüwa: Offline patching of individual VM
images in emulated environments– Mirage-based Nüwa: Batched offline patching using the
Mirage VM image library
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Wu Zhou, Peng Ning, Xiaolan Zhang, Glenn Ammons, Vasanth Bala, Ruowen Wang, "Always Up-to-date -- Scalable Offline Patching of VM Images in a Compute Cloud," in Proceedings of ACSAC 2010, December 2010.
Computer Science ACNS 2012
Some Evaluation Results
• Standalone Nüwa– Base VM image
• 64-bit Ubuntu 8.04; 406 patches (collected on 10/26/2009)• 402 patches can be applied offline (99%)
– Failure cases• Mono-gac package and three others that depend on it
• Mirage-based Nüwa– 100 VM images based on 32-bit Ubuntu 8.04
• Using 100 randomly selected subsets of basic Ubuntu tasks
– Top 8 security updates from Ubuntu Security Notices• Ranked by Ubuntu popularity contest• All data collected on 01/18/2010
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Computer Science ACNS 2012
Some Evaluation Results (Cont’d)
• Performance gain by standalone Nüwa– About 4 times speedup
* “Average” refers to the average of all 402 packages.
Computer Science ACNS 2012
Some Evaluation Results (Cont’d)
• Additional speedup by Mirage-based Nüwa– Another 2 – 10 times
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10 20 30 40 50 60 70 80 90 100
0
2
4
6
8
10
12
Speedup of Mirage-based batch patching over one-by-one patching
dbus
dash
libdbus
libfreetype6
Libpng12-0
libglib2.0-0
libxml2
udev
Number of images patched
Sp
ee
du
p
Computer Science ACNS 2012 16
Hypervisor Integrity Services
June 29, 2012
HyperSentry [CCS ’10]
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Example Service: HyperSentry
• Why HyperSentry?– Hypervisor is the highest privileged software– Compromise of hypervisor compromise of the system– Hypervisors cannot be blindly trusted
• Example #1: Xen owning trilogy [BlackHat 2008]
• Example #2: VM Ware ESX 3.x– 6/18/12: 67 Secunia advisories; 562 vulnerabilities; 7%
Secunia advisories not patched
– Hypervisor's code base is growing More vulnerabilities?
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HyperSentry
• HyperSentry– Stealthy and in-context measurement of hypervisor integrity
• Challenges– A fundamental problem
• How to measure the integrity of the highest privileged software?
– Hypervisor has full control of the software system (most of the time)• Scrubbing attacks• Tampering with the measurement agent• Tampering with the measurement results
– Relying on a higher privileged software goes back to the same problem
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Computer Science
The HyperSentry Approach
• HyperSentry– A generic framework to stealthily measure the integrity of a
hypervisor in its context
• Key ideas– Allow the measurement software to gain the highest
privilege temporarily– Measurement is triggered stealthily
• Scrubbing attacks
– Isolate measurement results from the hypervisor
June 29, 2012 ACNS 2012 19
Ahmed M. Azab, Peng Ning, Zhi Wang, Xuxian Jiang, Xiaolan Zhang, Nathan C. Skalsky, "HyperSentry: Enabling Stealthy In-context Measurement of Hypervisor Integrity,” in ACM CCS 2010, October 2010.
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Case Study: Verifying the Integrity of Xen
• Integrity measurement– Code: SHA-1 hash of Xen's code; Control flow verification– Date: Detect unauthorized sharing of physical pages across guest VMs
• Performance (on IBM HS21 XM blade server)– End-to-end execution time: 35ms– Periodical measurement: Every 8s: 2.4%; every 16s: 1.3%
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Isolated Execution Bypassing Hypervisor Control
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SICE[CCS ’11]
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VM VM VM
SICE: Strongly Isolated Computing Environment
June 29, 2012 ACNS 2012
Legacy Host(Hypervisor/OS)
Hardware
Virtualized Platform
VM VMVM/
Workload
Legacy Host(Hypervisor/OS)
Hardware
Virtualized Platform with SICE
SICE
Ahmed Azab, Peng Ning, Xiaolan Zhang, “SICE: A Hardware-Level Strongly Isolated Computing Environment for x86 Multi-core Platforms,” in Proceedings of ACM CCS 2011, October 2011.
Computer Science 23
Foundation of SICE
• System Management Mode (SMM)– x86 operating mode for system management functions– Single entry point: System Management Interrupt (SMI)– SMRAM: Isolated from the rest of system
• Not accessible by the system software (e.g., hypervisor)
– AMD processors implementation• Resizing the SMRAM at runtime• Separate SMRAM range for each CPU core
– Main challenges• SMM has escalated privileges• The CPU runs slowly and has limited functionality
June 29, 2012 ACNS 2012
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Foundation of SICE (Cont’d)
• Trusted/Secure boot
– Building the trust chain during system initialization• C-RTM BIOS Boot loader Initial hypervisor/OS image
– Secure hardware extensions (e.g., the TPM)• Seals and authenticates the measurement output
– Main challenge• Trust cannot be sustained due to potential runtime attacks