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Virtualisation – Security’s Friend or Foe?

• Virtualisation is set to consign traditional hardware appliances to the dustbin of computing history”

Roger Howorth, IT Week

• http://www.itweek.co.uk/itweek/comment/2162238/future-appliances-virtual

Virtualization Requirements• Scheduler• Memory Management• VM State Machine• Virtualized Devices• Storage Stack• Network Stack• Binary Translators (optional)• Drivers• Management API

Old: Virtual Server ArchitectureProvided by:

Windows

ISV

Virtual Server

Guest Applications

GuestsHost

Ring 1: Guest kernel mode

Ring 0: Kernel mode

IIS

Virtual Server

WebApp Virtual Server Service

Windows Server 2003/Windows XP

Kernel Device

Driver

Server Hardware

VMM Kernel

Ring 3: User mode

Windows (NT4, 2000, 2003)

VM additions

New: Hyper-V Architecture

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Ring “-1”

Provided by:

Rest of Windows

ISV

Hyper-V

New: Hyper-V Architecture

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Ring “-1”

Provided by:

Rest of Windows

ISV

Hyper-V

Hackers

Why not get rid of the parent?• No defence in depth• Entire hypervisor running in the most privileged mode of

the system

Ring “-”1

UserMode

KernelMode

UserMode

KernelMode

UserMode

KernelMode Ring 0

Ring 3

Virtual Machine Virtual Machine

Virtual Machine

• Scheduler• Memory Management• Storage Stack• Network Stack• VM State Machine

• Virtualized Devices• Binary Translators• Drivers• Management API

Hardware

Micro-kernelized Hypervisor• Defence in depth• Using hardware to protect• Hyper-V doesn’t use binary translation

• Further reduces the attack surface

Ring -1

VM State MachineVirtualized DevicesManagement API

Storage StackNetwork Stack

Drivers

UserMode

KernelMode

UserMode

KernelMode Ring 0

Ring 3

Virtual Machine Virtual Machine

Parent Partition

• Scheduler• Memory Management

Hardware

Security Assumptions• Guests are untrusted• Trust relationships

• Parent must be trusted by hypervisor

• Parent must be trusted by children

• Code in guests can run in all available processor modes, rings, and segments

• Hypercall interface will be well documented and widely available to attackers

• All hypercalls can be attempted by guests

• Can detect you are running on a hypervisor• We’ll even give you the

version• The internal design of the

hypervisor will be well understood

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Security Goals• Strong isolation between

partitions• Protect confidentiality and

integrity of guest data• Separation

• Unique hypervisor resource pools per guest

• Separate worker processes per guest

• Guest-to-parent communications over unique channels

• Non-interference• Guests cannot affect the

contents of other guests, parent, hypervisor

• Guest computations protected from other guests

• Guest-to-guest communications not allowed through VM interfaces

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Isolation• No sharing of virtualized

devices• Separate VMBus per VM to

the parent • No sharing of memory

• Each has its own address space

• VMs cannot communicate with each other, except through traditional networking

• Guests can’t perform DMA attacks because they’re never mapped to physical devices

• Guests cannot write to the hypervisor

• Parent partition cannot write to the hypervisor

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Hyper-V Security Hardening• Hypervisor has separate

address space• Guest addresses !=

Hypervisor addresses• No 3rd party code in the

Hypervisor• Limited number of channels

from guests to hypervisor• No “IOCTL”-like things

• Guest to guest communication through hypervisor is prohibited

• No shared memory mapped between guests

• Guests never touch real hardware I/O

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Hyper-V & Secure Development Lifecycle• Hypervisor built with

• Stack guard cookies (/GS)• Address Space Layout

Randomization (ASLR)• Hardware Data Execution

Prevention• No Execute (NX) AMD• Execute Disable (XD)

Intel• Code pages marked read only• Memory guard pages• Hypervisor binary is signed

• Hypervisor and Parent going through SDL• Threat modeling• Static Analysis• Fuzz testing & Penetration

testing

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Hyper-V Security Model• Uses Authorization Manager

• Fine grained authorization and access control

• Department and role based• Segregate who can manage

groups of VMs• Define specific functions for

individuals or roles• Start, stop, create, add

hardware, change drive image

• VM administrators don’t have to be Server 2008 administrators

• Guest resources are controlled by per VM configuration files

• Shared resources are protected• Read-only (CD ISO file)• Copy on write (differencing

disks)

Guest Applications

Child Partition

Parent Partition

Ring 3: User mode

Ring 0: Kernel mode

Virtualisation Stack

VM Service

WMI Provider

VM Worker Process

es

VM Worker Process

es

VM Worker Process

es

Server Core

Virtualization Service Providers

(VSPs)Windo

ws Kernel

Device

Driver

Windows hypervisor

Server Hardware

Virtualization Service

Clients (VSC’s)

VMBus

OSKernel

Enlightenments

Windows Server Core• Windows Server frequently deployed for a single role

• Must deploy and service the entire OS in earlier Windows Server releases

• Server Core a new minimal installation option• Provides essential server functionality• Command Line Interface only, no GUI Shell

• Benefits• Fundamentally improves availability• Less code results in fewer patches and reduced servicing

burden• Low surface area server for targeted roles• More secure and reliable with less management

Windows Server Core

What tools can help secure the Environment?• IPSec for host authentication• Use the principle of least privilege• Only install software you have a reason to trust• Ensure policy compliance – Network Access Protection

can be a huge help• Keep things as simple as possible• Add functionality as high up the stack as possible

How to proceed?• Virtualisation is not a silver bullet for security

problems• Nor is it a nightmare• It just changes the threat landscape

• Carefully consider the impact on trust boundaries and the knock-on effect of compromised security at layers underneath the applications – the deeper down the stack, the worse the impact

What is Microsoft Forefront?• Microsoft Forefront is a comprehensive line of

business security products providing greater protection and control through integration with your existing IT infrastructure and through simplified deployment, management, and analysis.

EdgeClient and Server OS

Server Applications

IT Service Management

Data Protection Manager ‘Service

Desk’ Capacity Planner Reporting

Manager Operations Manager Client

Data

Storage &

RecoveryProblem

ManagementCapacity Management

IT ReportingClient Operations

Management

Configuration Manager

Operations Manager

Performance & AvailabilityMonitoring

Software Update &

Deployment

Microsoft System Centre

Enabler for Microsoft’s Best Practices

Microsoft Operations Framework

Infrastructure Optimization

Next steps• Receive the latest Security news, sign-up

for the:• Microsoft Security Newsletter • Microsoft Security Notification Service

• Assess your current IT security environment• Download the free Microsoft Security

Assessment Tool

• Find all your security resources here http://www.microsoft.com/uk/security/infosec2008

Session Evaluation• Hand-in you session evaluation on your way out

• Win one of 2 Xbox 360® Elite’s in our free prize draw*

• Winners will be drawn at 3.30 today

• Collect your goody bag which includes.  • Windows Vista Business (Upgrade), • Forefront Trials, • Forefront Hand-On-Labs• Security Resources CD

• I’ll be at the back of the room if you have any questions

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