Fine grained access control for cloud-based services

© 2012, Axiomatics AB 1

Fine-Grained Authorization for Cloud-based Services

David BrossardAxiomatics

@davidjbrossard - @axiomatics

© 2012, Axiomatics AB 2

3 strategies to extend authorization to the CloudWe’re in London, we definitely need this strategy

What it means forcustomersSaaS providers

What you will learn

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Access control or authorization (AuthZ)Who can do what?“The authorization function determines whether a particular entity is authorized to perform a given activity, typically inherited from authentication when logging on to an application or service.”

What’s authorization?

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Heard enough about SSO, federation and SAML?Authentication: Hi, I prove who I say I am

One-off processFocus: user’s identity and the proof of identityStandards: OpenID, OAUTH, SAML…

Authorization: Hi, can I transfer this amount?From code-driven to policy-drivenStandard: XACML

Authorization comes after Authentication

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The issue with Authorization today

The black box challenge

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System growth leads to AuthZ challenges

App

App

App

Cost

Brittleness

Static

Risk

Lack of visibility

Lack of audit

Violation of SoD

SaaS

SaaS

SaaS

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What happens to my data?Who can access which information?How do I comply with (what the auditor will ask for)

Regulations? E.g. Export Control

Contractual obligations?

Going to the cloud doesn’t make it easierDo I need a different approach for cloud?

The Authorization Challenge

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Export ControlKnow the user (citizenship, location, affiliation)Know the end use (end location, purpose of use)

Example: Manufacturing in the cloud

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Fine-grained authorization to the rescue

Attribute-based access controlXACML

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Authorization is nearly always about

Who?

Identity + role (+ group)

Role-based

Access

Control

Credits: all icons from the Noun Project | Invisible: Andrew Cameron

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Authorization should really be about…

When?What? How?Where?Who? Why?

Attribute-

based

Access

Control

Credits: all icons from the Noun Project | Invisible: Andrew Cameron, | Box: Martin Karachorov | Wrench: John O'Shea | Clock: Brandon Hopkins

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eXtensible Access Control Markup LanguageOASIS standardXACML is expressed as

A specification document (a PDF) andAn XML schema

Policy-based & attribute-based languageImplement authorization based on object relationsOnly employees of a given plant can see technical data linked to items assigned to the plant

Behold XACML, the standard for ABAC

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Refresher: the XACML architecture

DecidePolicy Decision Point

ManagePolicy Administration Point

SupportPolicy Information PointPolicy Retrieval Point

EnforcePolicy Enforcement Point

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XACML Transparent & Externalized AuthZCentrally managed policy: ”PERMIT user with clearance X to read document classified as ….”“DENY access to classified document if…”

User Application

Informationasset

I want…

PERMITorDENY?

PERMITorDENY?

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XACML Anywhere AuthZ & Architecture

Datacenter

App AService A

Service D

Service E

Service M

Service O

SaaS SaaSPrivate Cloud

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Fine-grained Authorization for the Cloud

Three strategies for externalized authorization in the cloud

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A SaaS provider should offerFunctional APIs (their core business)Non-functional (Security) APIs

Let customers push their own XACML policiesApply the administrative delegation profile

http://docs.oasis-open.org/xacml/3.0/xacml-3.0-administration-v1-spec-en.html

Option #1 – tell your provider to adopt XACML

SaaS provider

Option #1 – Architecture

Central IT:Company A

SaaS Admin delegates rights to manage access control provided to customer A. The rights are restricted to only the applications and resources provided to this particular customer’s users.

Customer A’s admin can manage access for their staff on its own by providing XACML policies and attributes

Customer A users use the SaaS application

18© 2012, Axiomatics AB

App#1

App#2

App#3

Func

tiona

l API

XACML Mgmt

API

1.

2.

3.

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ProsConsistent access controlFine-grainedRisk-awareFuture-proofSaaS vendor benefit

multi-tenancy

ConsNot many SaaS vendors support XACML today

Option #1 – Pros & Cons

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If you can restrict access to SaaS applications from within the corporate network…All access to SaaS apps could be made to tunnel through a proxy

Option #2 – Proxy your cloud connections

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Option #2 – Architecture

SaaS App #1

SaaS App #2

SaaS App #3

VPN

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ProsWorkaround current SaaS limitationsEasy to deployAvailable today

ConsNo direct access to SaaS app

Forces users to go via VPN

Access may not be as fine grained as Option #1

Lack of visibility into the SaaS data

Option #2 – Pros & Cons

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What if the provider is reluctant to adopt XACML?“If the application won’t go to XACML then XACML will go to the application”

Eve Maler, Forrester

You still getCentrally managed authorizationStandards-based (XACML)

ApproachConvert from XACML to expected SaaS formatPush via SaaS management APIs

Option #3 – Policy Provisioning based on XACML

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SaaS provider

Option #3 – Architecture

Central IT:Company A

Convert XACML policies to the native format expected by the SaaS provider

Customer A users use the SaaS application

App#1

App#2

App#3

Func

tiona

l API

Native API

Authorization constraints / permissions in the format expected by the SaaS provider

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ProsFeasible todayViable solutionExtends the customer’s XACML-based authorization system’s reach

ConsPossible loss of XACML richness in access controlLoss of dynamic nature

Option #3 – Pros & Cons

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Cloud requires eXtensible AuthorizationFine-grainedExternalized

Traditional approaches#1: tell your SaaS provider to adopt XACML.#2: proxy your cloud connections.

Extended approach#3: Policy Provisioning based on XACMLAlso works for business apps (SharePoint, Windows)

To summarize

Every cloud has a XACML lining

Questions?Contact us at info@axiomatics.com