Windows Azure Security
Agenda
Introduction
Azure™ Compute Security Azure Storage Security
SQL Azure™ Security Questions
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
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Security Threats
Azure
Customer Tenant
Customer Admin User
From Subscription Portal
•
Create a Compute Tenant•
Create a Storage Account•
Create a SQL Azure DatabaseOnce created, they are managed via separate mechanisms Customer authenticates to Subscription Portal using LiveID
Agenda
Introduction
Azure Compute Security Azure Storage Security
SQL Azure Security Questions
Underlying Hardware
Rack-mounted serversEach rack has a collection of identical nodes
Each node (currently) has 2 CPU chips with 4 cores each 16 Gig of memory
Disks for local storage
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Hypervisor and VM Sandbox
All Guest access to network and disk is mediated by Root VM (via the Hypervisor)
Hypervisor Network/Disk R o o t V M G u e s t V M G u e s t V M G u e s t V M G u e s t V M G u e s t V M G u e s t V M G u e s t V M
What Does the World Look Like to a
Guest VM?
1, 2, 4, or 8 CPUs; up to 14 GB of memory Three disk drives:
•
C:\ (for temps; initially populated with config file)•
D:\ (for application code; initially as supplied by customer admin)•
E:\ (for OS code; initially as supplied by Azure)Network connectivity to Internet via NAT and to other VMs of same tenant
Guest agent accepts incoming HTTP/RPC connections from Root OS
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Handling Attacks by a Tenant
Not dependent on the security of Windows®
Instead, dependent on the security of the Hypervisor and the exposed network and disk drivers
C:\, 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
Root OS Services
Disk I/O remapping and bandwidth quota enforcement Network Packet Filter and bandwidth quota enforcement
•
No forging of IP address or false responses to ARPs•
Connectivity only to Internet, peer VMs within tenant, and a small set of specific services (e.g., DNS)12
Azure Network Services
For scalability, customer tenants can be divided into roles
•
(e.g., front end, back end)Roles can have multiple instances
Azure will divide incoming connections among front-end role instances
When a new role instance is created, its disks (C:\, D:\, and E:\) are initialized. When a role instance is discarded, the contents of its disks are discarded. Compute holds only ephemeral data – permanent data must be kept in Azure Storage, SQL Azure, or an external customer-provided store.
High availability is achieved through fast failover. Individual VMs can be discarded and reinitialized at any time.
Recovery from Any Sort of Failure
If a customer VM fails, the Root VM can reboot it or – ifnecessary – reinitialize all of its on-disk state
If a Root VM fails or an entire node fails, the Fabric Controller can power cycle the node, reboot it from the network, and reinitialize all of its actual disks
All customer VMs can be migrated to other nodes while the node is being tested before it is returned to service or queued for manual repair
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Handling Attacks by a Customer
Administrator
Customer Administrator gets to specify:
•
How many roles in a tenant, how many instances of each role, and what size VM each runs on•
The application software that runs in each VM and its configuration•
Certificates, passwords, and secret keys each VM can use to authenticate to other entitiesRequests go through the Developer Portal (browser based) or Developer API (RPC over HTTP over SSL)
Authentication to Developer API uses a certificate and private key registered through the Developer Portal
Protecting the Fabric Controllers
Guest Agent Guest VM Fabric Agent Root VM Hypervisor Fabric Controller Developer API Developer Portal16
Handling Attacks by an End User
Azure divides incoming connections among front-end role instances
Customer has all the facilities of Windows to protect the VM against end-user attacks
Azure must deal with DDoS (bandwidth) attacks that could overwhelm all of Azure
Customer must deal with DDoS attacks that could overwhelm the customer front ends
Internet Gateways
Gateways are shared with other Microsoft properties (e.g., Hotmail®, MSN®, Live, …)
Very high speed links at multiple locations worldwide
Not impossible to overload, but one of the highest capacity targets deployed today
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One More Problem to Worry About…
Azure could be used as a platform for attacking other Internet sites
A customer tenant could be recruited into a bot army to spread spam or participate in DDoS attacks
A customer could intentionally participate in such things
We have to be responsive to complaints from other Internet sites that they are under attack from one of our tenants
Agenda
Introduction
Azure Compute Security Azure Storage Security SQL Azure Security
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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
•
Fine-grained access controls are not implemented•
A customer wanting fine-grained access controls canimplement a front-end compute tenant that has full access to the storage account but mediates access to data items
Azure Storage Scalability
To reduce the need for locks when dealing with a conventional file system, Azure storage implements the primitives: blobs, tables, and queues.
For backwards compatibility, it also implements an XDrive with disk semantics for applications that have not been
converted.
The customer is responsible for coordinating the assignment of XDrives to VMs. An XDrive can only be open from one VM at a time.
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Azure Storage Security
Data from many customers is mixed in a single pool
Access to data in a specific account is only granted to entities having the secret key for that account
Storage 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 rollover
Access Control Extensions
To deal with some common cases:•
Blobs can be marked as “world readable”, which allows them to be read without authentication by anyone knowing their name•
Queries can be HMAC signed with some of their parameters unspecified. Passing such a query and its signature to aAgenda
Introduction
Azure Compute Security Azure Storage Security SQL Azure Security Questions
Azure SQL
As with storage, runs on separate hardware with no
connectivity to compute except (logically) over the Internet Subscription portal can create databases
Data from many customers is pooled in a single SQL instance, but they are treated as separate and access controlled
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