Windows Azure Security Features and FunctionalityVivek Bhatnagar WW Lead Technical Sales Windows Azure Microsoft Corporationvivekbh@live.com

Windows Azure Security…

Windows Azure Combines Three Components

Compute – Think Stateless CPU in the Cloud(Rented by the CPU - hour)

Storage – Like a file system, but structured differently to support scalability and parallelism

(Rented by the Gigabyte - Month)SQL Azure – Another form of storage, accessed with SQL queries rather than file-like operations

Can be used separately, but more commonly a Compute tenant is layered atop Storage, SQL Azure, or both

There will likely be more components in the future

Responsibility for Threat Mitigation

There are many threats to a traditional serverThere are some additional threats in the case of cloud computingSome threats are handled by Windows Azure; others remain the responsibility of the customer

Threats We Worry About

Windows Azure

Customer Tenant

Customer Admin Users

External Web Site

Physical AttacksOn ServersCentral Admin

Attacks against Windows Azure

A successful attack on the infrastructure could compromise all of our customersWindows Azure must secure its facilities against unauthorized accessWindows Azure must secure its interfaces against attacks over the network

Customer tenants breaking out of their VMsAttackers successfully impersonating customer administrators or Windows Azure administratorsCustomer administrators affecting other than their own tenants

Windows Azure

Customer Tenant

Customer AdminUsers

Physical AttacksOn Servers

Abuse of Privilege by Windows Azure AdministratorsWindows Azure administrators could

make unauthorized access to customer data

Procedures involving customer consent when such access is necessarySeparation of Duty to prevent abuse by a single rogue administratorAuditing to assure that unauthorized access will be discovered

Windows Azure

Customer Tenant

Central Admin

Using Windows Azure as a Platform for Attacking

OthersWe will receive complaints of misbehavior by Windows Azure tenantsWe proactively monitor outbound access to detect common cases (port scans, spam)If a good customer’s tenant has been compromised (botted), we work with the customer to resolve the problemIf a customer intentionally attacks others, we ban them

Windows Azure

Customer Tenant

External Web Site

Threats Customer Still Must Worry About

Windows Azure

Customer Tenant

Customer Admin Users

Attacks on a Customer’s Tenant

A tenant is much like a physical server. If there are bugs in its code, it can be compromised over the networkWe can look for symptoms in some cases, but it is ultimately the customer’s responsibility

Windows Azure

Customer Tenant

Users

Abuse of Privilege by a Customer Administrator

Customer administrators are authorized to update the code and access the data belonging to any customer tenantCustomer administrators are authenticated with cryptographic keys that the customer must protectCustomers should implement deployment practices as carefully as they would for applications in their own data centers

Windows Azure

Customer Tenant

Customer Admin

Windows Azure Security LayersManaged Code Access Security: partial trust

Windows Account: running with least privileges

Windows FW (VM): rules based on service model

Virtual Machine: fixed CPU, memory, disk resourcesRoot Partition Packet Filter: defense in depth against VM “jailbreaking”Network ACLs: dedicated VLANS for tenant nodes

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How does it work?

For Windows Azure Storage and SQL Azure, like any other shared service

Storage or SQL account owned by some customer who sets access policyAccess policy is enforced by the code that parses and satisfies requests

For Windows Azure Compute, we create customer owned VMs, isolated by a hypervisor

Underlying Hardware

Rack mounted serversEach rack has a collection of identical nodesEach node (currently) has 2 CPU chips with 4 cores each

16 Gig of memoryDisks for local storageNetwork Interface to a Top of

Rack Switch

Hypervisor & VM Sandbox

All Guest access to network and disk is mediated by Root VM (via the Hypervisor)

Hypervisor

Network/Disk

Root VM

Guest VM

Guest VM

Guest VM

Guest VM

Guest VM

Guest VM

Guest VM

Managing it all through the Fabric Controllers

What does the world look like to a Guest VM?

1, 2, 4, or 8 CPUs; up to 14 GB or memory

Three disk drives:

C:\ (for temps; initially populated with config file)

D:\ (for OS code; initially as supplied by Windows Azure)

E:\ (for application code; initially as supplied by customer admin)

Network connectivity to Internet via NAT and to other VMs of same tenant

Guest agent accepts incoming HTTP/RPC connections from Root OS

Handling Attacks by a Tenant

Not dependent on the security of WindowsInstead, dependent on the security of the Hypervisor and the exposed network and disk driversC:\, D:\, and E:\ are not really disks. They are VHD files in the root OS’s file system.Attack surface is minimized by accepting few commands and supporting only a few hardware devices

Windows Azure Storage

Runs on separate hardware with no network connectivity to compute except (logically) through Internet

Requests run over HTTP and optionally over SSL with server authentication

Storage is organized into storage accounts

A single customer may have many storage accounts

A single secret key controls all access to a storage account

Access Control

Some accommodation to more fine-grained access controls:• Some data can be marked as world-

readable• Shared access signatures supports

some forms of limited delegationA customer wanting fine-grained access controls can implement a front end compute tenant that has full access to the storage account but mediates access to data items

Windows Azure Storage Scalability

To reduce the need for locks when dealing with a conventional file system, Windows Azure storage implements the primitives: blobs, tables, and queues.For backwards compatibility, it also implements an virtual drive with disk semantics for applications that have not been converted.The customer is responsible for coordinating the assignment of virtual drives to VMs. A virtual drive can only be open for write from one VM at a time.

Windows Azure Storage Security

Data from many customers is mixed in a single poolAccess to data in a specific account is only granted to entities having the secret key for that accountStorage keys are randomly generated when the storage account is created (or later at the request of the customer)A storage account may have two active keys at any given time to support key rolloverStorage keys are used to HMAC sign each access request

SQL Azure

As with storage, runs on separate hardware with no connectivity to compute except (logically) over the InternetDeveloper portal can create databases and set an administrator passwordSQL administrator can create additional user accounts, each authenticated with a passwordData from many customers is pooled in a single SQL instance, but they are treated as separate and access controlled independently

Defenses Inherited by Windows Azure Tenants

SpoofingTampering & Disclosure

Port Scanning/ Service

Enumeration

Elevation of

PrivilegeLoad-balanced Infrastructure

Network bandwidth throttling

CiscoGuard enabled on Storage nodes

Configurable scale-out

Denial of Service

Service Definition file, Windows Firewall, VM switch packet filtering

VM switch hardening

Certificate Services

Shared-Access Signatures

HTTPS

Sidechannel protections

VLANs

Top of Rack Switches

Custom packet filtering

Partial Trust Runtime

Hypervisor custom sandboxing

Virtual Service Accounts

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