Hardware-Assisted Isolated Computing Environments Instructor: Kun Sun, Ph.D

Hardware-Assisted Isolated Computing Environments

Instructor: Kun Sun, Ph.D.

Introduction Related Work Our Work on Hardware-assisted ICE

x86 platform SecureSwitch: OS level isolation [NDSS12]

ARM platform TrustICE: Flexible ICE [under submission]

Summary

Outline

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Bring your own device (BYOD) Risk of data breaches Require an ICE to separate

sensitive code and data Suspicious code or data

Trojan, e.g., BitCoinMiner, Keylogger

Run the code in an ICE to protect the host environment

Malware analysis Rootkits compromises OS Protect the analysis tools in an

ICE

Why Isolated Computing Environment?

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http://www.technologyreview.com/sites/default/files/legacy/belt_b_x220.jpg

http://b.vimeocdn.com/ts/419/611/419611391_640.jpg

Lampson Red/Green System Model

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Red/Green system: Policy + Isolation + Accountability +Freedom* Butler Lampson, Accountability and Freedom Slides, Microsoft, Sept.,2005




Summary

Outline

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Software-based ICE Solutions

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VMM-based OS-based Browser-based

Isolation Level

OS level User/Process level Applet level

Example Xen, VMware, QEMU, UML

FreeBSD Jail, Linux OpenVZ, Solaris Container

Adobe Flash, Java applets, Silverlight

Security concerns

VMM vulnerabilities*,Covert Channel

VMM vulnerabilities,OS vulnerabilities

VMM vulnerabilities,OS vulnerabilities,Browser vulnerabilities

* From 1999 to 2009, 373 vulnerabilities affecting virtualization solutions. --- “IBM X-Force 2010 Mid-year trend and risk report”

Multiple Computers

Multi-boot VT-x / SVM(DRTM)

SMM

Isolation Level

Whole physical computer

OS level; Instruction level;

Instruction level;

Examples Bootloader:LILO, Grub

Flicker [2],TrustVisor [3]

SICE [5],HyperCheck [6]

Problems Cost, inflexible

Long switching time

Software compatibility

Software compatibility

Hardware-based ICE Solutions

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Summary

Outline

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BIOS-assistant OS Level Isolation

no data leakage between two OS environments

without using any mutable software layer (e.g., hypervisor)

no changes of the OS source code

fast switching time, around 6 seconds

SecureSwitch Architecture

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App3App2App3App2

Trusted OS

BIOS CPU, VGA, NIC, I/O

App1

Untrusted OS

App1

Trusted Computing Base (TCB) only contains the BIOS.

Basic Input/Output System (BIOS) Initializing hardware components. Stored in non-volatile ROM chips.

Unified Extensible Firmware Interface (UEFI) A new software interface between OS and

firmware. Partially open source

Coreboot (formerly as LinuxBIOS) Similar functionality as UEFI Open source

BIOS, UEFI, and Coreboot

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Advanced Configuration and Power Interface (ACPI) OS-directed configuration; Power/thermal management

Global System States G0 --- Working (System Operational) G1---Sleeping (CPU stopped) G2 ---Soft Off G3 ---Mechanical off (Physical off switch)

Sleeping States in G1: S0 – S5 S3: also called Standby, Suspend to RAM

DRAM still maintained S4: also called Hibernation or Suspend to Disk

DRAM not maintained Device Power States: D0 – D3

D0 - Fully-On D3 -- Power off to device

ACPI Sleeping States

Assumption BIOS and option ROM on devices can be trusted. No physical access to the protected machine

Attacks from the untrusted OS Spoofing Trusted OS attacks: faking trusted OS Data exfiltration attacks: stealing sensitive data Cache-based side channel attacks: extracting sensitive

data

Out of the scope Denial of Service attacks Network attacks on trusted OS

Attack Model

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Secure Switching State Machine

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Protect against Spoofing trusted OS attacks by assuring users that they are working with the OS they intend to use.

1. Protecting system variables OS_Flag: records which OS should be woken next Where to save it?

2. Untrusted OS should be truly suspended. hardware controlled power LED lights up when

system is powered on, and blinks in the sleep mode.

3. BIOS should be entered. Press the power button.

Trusted Path

OS_Flag: physical jumper, e.g., Parallel port connector

Secure Switching Process

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Untrusted OS(running)

Trusted OS(ACPI S3 sleep)

(1) Suspend

Trusted OS(ACPI S3 sleep)

Untrusted OS(ACPI S3 sleep)

Power Button

(2) press button

(4) hardware configuration

CPU, RAM, Hard Disk

(5) wake up trusted OS

Trusted OS(running)

Untrusted OS(ACPI S3 sleep)

(6) wake up

BIOS

OS_FLAG

(3) read OS_FLAG

CPU Isolation: two OSes never run concurrently. Memory Isolation: physical-level isolation Hard disk isolation: encrypted hard disk, RAM disk Other I/O isolation: clean the buffers/states in

devices.

System Isolation

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CPU Memory Hard Disk VGA NIC

ACPI S3

BIOS

A motherboard may have more than one dual in-line memory module (DIMM) slot.

DIMM Mask and DQS Setting BIOS uses “DIMM_MASK”variable to

control which DIMMs to be enabled. BIOS sets “data strobes”(DQS)

parameters to enable DDR RAM memory access.

Memory Isolation

Physical-level memory isolation ensured by BIOS Two OS environments run in separate DIMMS.

BIOS only enables one DIMM for each OS. Two DQS settings for two OSes “DIMM_MASK” controlled by the physical jumper.

System software, except the BIOS, cannot initialize or enable DIMMs after the system boots up Transient state of DQS setting If “DIMM_MASK”has conflicts with DQS setting,

system crashes

Memory Isolation

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Hard disk encryption Two hard disks, one for each OS Disk lock in ATA specification Need TPM to save the encryption key

RAM disk For browser-based application, save a small

amount of temporary data in the RAM

Hard Drive Isolation

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> Hardware> Motherboard: ASUS M2V-MX_SE> CPU: AMD Sempron 64 LE-1300> DDR2: Kingston HyperX 1GB> HDD: Seagate 500GB

> Software> BIOS: Coreboot + SeaBIOS> Trusted OS: Linux (Centos 5.5)> Untrusted OS: Windows XP

Prototype

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Performance Analysis

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Linux Suspend Time Breakdown

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User Space : 1517.33 ms Kernel Space: 1590.14 ms

Linux Wakeup Time Breakdown

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User Space: 621.04 ms Kernel Space: 1537.22 ms




Summary

Outline

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Two isolated domains Secure/un-secure CPU States Virtual MMU/Secure Memory TrustZone-Aware interrupt

controller Traditional solutions

Rich OS and un-secure apps in normal domain

Secure OS and secure apps in secure domain

Limitations Trusted Computing Base (TCB) is

large No flexible

No isolation between secure Apps.

No protection on non-secure Apps.

ARM TrustZone

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Traditional Solutions

Basic Idea: Create ICEs in normal domain, instead of secure domain

A Trusted Domain Controller (TDC) enforces the isolation and secures the switching

Benefits: Small TCB: TDC + Secure boot Multiple ICEs

Self-contained code Microkenel with necessary modules full-featured OS

Flexible Easy to deploy third-party software Vendor Apps still in secure domain

TrustICE: Flexible ICEs

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Summary

Outline

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Our Work on Hardware-assisted ICE SecureSwitch: BIOS-based ICE on x86

platform OS level isolation with small TCB Small switching time

TrustICE: TrustZone-based ICE on arm platform

Flexible multiple ICEs Small TCB

Summary

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1. P. Barham, B. Dragovic, K. Fraser, S. Hand, T. Harris, A. Ho, R. Neugebauer, I. Pratt, and A. Warfield. Xen and the art of virtualization. In SOSP ’03: Proceedings of the nineteenth ACM symposium on Operating systems principles, pages 164–177, New York, NY, USA, 2003. ACM Press.

2. J. McCune, B. Parno, A. Perrig, M. Reiter, and H. Isozaki. Flicker: An execution infrastructure for TCB minimization. In Proceedings of the 3rd ACM SIGOPS/EuroSys European Conference on Computer Systems 2008, pages 315–328. ACM, 2008.

3. J. M. McCune, Y. Li, N. Qu, Z. Zhou, A. Datta, V. Gligor, and A. Perrig. TrustVisor: Efficient TCB reduction and attestation. In Proceedings of the IEEE Symposium on Security and Privacy, 2010.

4. Amit Vasudevan, Bryan Parno, Ning Qu, Virgil D. Gligor, Adrian Perrig. Lockdown: Towards a Safe and Practical Architecture for Security Applications on Commodity Platforms. TRUST 2012.

5. Ahmed Azab, Peng Ning, Xiaolan Zhang, SICE: A Hardware-Level Strongly Isolated Computing Environment for x86 Multi-core Platforms, in Proceedings of 18th ACM Conference on Computer and Communications Security (CCS11), October 2011.

6. Fengwei Zhang, Jiang Wang, Kun Sun, Angelos Stavrou, "HyperCheck: A Hardware-Assisted Integrity Monitor," IEEE Transactions on Dependable and Secure Computing, 17 Dec. 2013. IEEE computer Society Digital Library.

7. Kun Sun, Jiang Wang, Fengwei Zhang, and Angelos Stavrou, SecureSwitch: BIOS-Assisted Isolation and Switch between Trusted and Untrusted Commodity OSes. In the Proceedings of the 19th Annual Network & Distributed System Security Symposium (NDSS), San Diego, California, 5-8 February 2012.

8. Y. Fu and Z. Lin. Space Traveling across VM: Automatically bridging the semantic gap in virtual machine introspection via online kernel data redirection. In Proceedings of the 33rd IEEE Symposium on Security and Privacy, 2012.

9. X. Jiang, X. Wang, and D. Xu. Stealthy malware detection through vmm-based out-of-the-box semantic view reconstruction. In Proceedings of the 14th ACM conference on CCS, 2007.

10. T. Leek, M. Zhivich, J. Gin, and W. Lee. Virtuoso: Narrowing the semantic gap in virtual machine introspection. In Proceedings of the 32nd IEEE Symposium on Security and Privacy, 2011.

References

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Hardware-Assisted Isolated Computing Environments Instructor: Kun Sun, Ph.D