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Security Strategies

C
O
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Making your SAP systems available through the

platforms and devices in which your users already

spend their time is a boon to business growth —

however, it also presents the challenge of ensuring

secure, seamless access to your data. To help, SAP

offers SAP NetWeaver Gateway, a development

framework that allows you to expand the reach of

your SAP software across a wide range of devices

and platforms, including mobile, collaborative,

and social media environments, and to do so with

speed, ease, and at a low cost.

Based on market standards,1 SAP NetWeaver

Gateway allows non-SAP developers to use the

development tool of their choice to quickly

create and deploy rich applications that connect

users, via services, to SAP back-end software.

SAP NetWeaver Gateway also secures network

communications to help keep data protected

and works with several types of authentication

mechanisms, including those that enable single

sign-on (SSO), to create a more seamless user

experience. In this article, we’ll provide you with

an overview of how SAP NetWeaver Gateway

security works, and the options available for

authentication and SSO.2

Understanding SAP NetWeaver
Gateway Security
Network communications and user authorizations

are critical to maintaining control over your data.

1 This includes the Open Data Protocol (OData), which was
recently submitted to OASIS for standardization.

2 See “SAP NetWeaver Gateway Extends the Reach of SAP
Business Applications” by Adi Kavaler in the July-September
2011 issue of SAPinsider (sapinsider.wispubs.com).

Fortunately, SAP NetWeaver Gateway supports

the infrastructure you already have in place for

network security and user authorizations, so you

don’t have to reinvent the wheel.

Network and Communication Security
Instead of using proprietary protocols, the com-

munication between SAP NetWeaver Gateway

and the consumer (the browser-based or cloud

application, mobile device, etc.) is based on the

OData Protocol. This is an HTTP-based protocol

in which the interaction between the client and

the SAP NetWeaver Gateway server resembles

how an end user would browse web pages. The

communication is facilitated via the Internet

Communication Manager (ICM) process of SAP

NetWeaver Application Server, using handlers in

the Internet Communication Framework (ICF).

This means that SAP NetWeaver Gateway sup-

ports the same authentication options offered

by the underlying SAP NetWeaver Application

Server ABAP runtime. The communication

exchange can be easily encrypted using HTTPS

and secured using a reverse proxy, such as the

SAP Web Dispatcher, which provides protection

on the protocol level.

Communication between SAP NetWeaver

Gateway’s server and the SAP Business Suite

back-end system is based on SAP remote func-

tion calls (RFCs). The trusting/trusted system

relationship established by the RFC connection

enables SSO between the server and the back-end

systems. The SAP NetWeaver Gateway infrastruc-

ture also includes token-based CSRF (Cross-Site

Request Forgery) protection, which checks all

Take Advantage of Cross-Platform,
Cross-Device Access While
Keeping Your Data Secure
with SAP NetWeaver Gateway
by André Fischer and Genady Podgaetsky, SAP AG

Genady Podgaetsky (genady.
[email protected]) is a
Security Expert for
SAP NetWeaver Gateway
and Duet Enterprise prod-
ucts. Genady has been with
SAP since 2005 and has 16
years of experience in the
computer industry.

André Fischer (andre.
[email protected]) is a Product
Manager for SAP NetWeaver
Gateway who joined SAP in
2004. André often speaks
at SAP TechEd and has
published numerous articles
and blogs about SAP security-
related topics.

This article appeared in the Jul n Aug n Sep 2012 issue of
SAPinsider (http://sapinsider.wispubs.com) and appears
here with permission from the publisher, WIS Publishing.

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modifying requests from a user’s browser to the

SAP NetWeaver Gateway server for a valid CSRF

token. In addition, virus scanning can be per-

formed on incoming update and create requests

for SAP NetWeaver Gateway services that are

used to upload documents to the back-end SAP

Business Suite system.

User Management and Authorizations
Since you can deploy SAP NetWeaver Gateway

as an add-on to the ABAP runtime of SAP

NetWeaver Application Server, SAP NetWeaver

Gateway is able to leverage the user management

and authorization concepts that are currently in

place in your back-end SAP systems so you don’t

have to maintain a separate configuration for

SAP NetWeaver Gateway authorizations and

user management.

It is also possible to define ABAP authorization

roles in the SAP NetWeaver Gateway system to

control access to SAP NetWeaver Gateway ser-

vices using a “white list” approach. This means

only users assigned to a predefined role in the

SAP NetWeaver Gateway system can access the

services. With this approach, even if user access is

granted at the service level, the SAP user authori-

zations are checked in the back-end system against

the assigned ABAP authorizations.

Some SAP customers may choose to run

SAP NetWeaver Gateway on a separate SAP

NetWeaver Application Server to protect their

SAP back-end systems from malicious requests

coming from the outside. In scenarios like this,

SAP NetWeaver Gateway can be easily connected

to an existing central user administration or iden-

tity management system landscape for user/role

synchronization.

Now that you understand how user manage-

ment and network communication is secured

with SAP NetWeaver Gateway, let’s review the

options available for authentication.

Authentication Options with
SAP NetWeaver Gateway
There are different methods for implementing

authentication with SAP NetWeaver Gateway,

depending on the scenario in which you want to

use it. For example, to ensure the security of your

back-end data, a web application that is external

to your SAP landscape requires a different type

of authentication to SAP NetWeaver Gateway

than a native client-side or desktop application

that resides within your system landscape.

To meet the needs of different scenarios, SAP

NetWeaver Gateway supports several authentica-

tion options, including options that enable SSO.

SAP NetWeaver Gateway at a Glance
SAP NetWeaver Gateway is an add-on to the ABAP technology platform that
can be deployed either on a separate server or locally on an SAP Business Suite
system. SAP NetWeaver Gateway also integrates with Sybase Unwired Platform
and Duet Enterprise.

As shown in the figure below, SAP NetWeaver Gateway forms a bridge
among various consumer channels (mobile and non-mobile clients, such as
browser-based applications, smartphones, tablets, the cloud, and enter-
prise software) and the business layer of an existing SAP solution landscape.
Through SAP NetWeaver Gateway, SAP Business Suite data can be exposed
by services that support the Open Data Protocol (OData) , which is a simple
HTTP-based protocol for accessing data that is commonly used by mobile
applications and HTML5 web applications.

Browser-based
applications

Mobile
devices Cloud

Consumer
devices

Enterprise
software

SAP Business Suite

CRM SRM SCM PLM ERP

Sybase Unwired
Platform

Duet Enterprise

SAP NetWeaver Gateway

 SAP NetWeaver Gateway connects devices, environments, and platforms to

SAP software solutions

Note: To enable a trusted RFC connection between the

SAP NetWeaver Gateway system and back-end systems,

you must ensure that the usernames are identical in both.

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Browser-Based SAML 2.0 Authentication
Security Assertion Markup Language (SAML),

currently in version 2.0, is an XML-based open

standard that allows you to enable SSO with SAP

NetWeaver Gateway using the authentication

options you already have in place. A typical

SAML setup includes an identity provider (IdP)

from solutions (such as SAP NetWeaver Single

Sign-On3 or Microsoft Active Directory Federa-

tion Services) that create SAML assertions and a

service provider (such as SAP NetWeaver Gate-

way) that receives the SAML assertions. The

consumer can authenticate to the IdP using one

of the authentication options supported by the

IdP, receive a SAML assertion, and forward it to

SAP NetWeaver Gateway to enable login.

Browser-based SAML 2.0 authentication does
not require deployment of client certificates, mak-

ing it an ideal authentication option for web-based

SSO access — users in such scenarios cannot be

expected to install software or certificates in their

environments. You can also use browser-based

SAML 2.0 authentication in intranet scenarios by

leveraging Integrated Windows Authentication to

authenticate the IdP and achieve SSO.

X.509 Client Certificate Authentication
X.509 client certificates are widely accepted and

supported as the standard for identity authenti-

cation. In this method, a digital certificate with

the user’s public key is sent to the server, which

then validates the certificate and allows login.

X.509 client certificates usually require a public

key infrastructure (PKI) to handle the certificates.

Customers that do not have a PKI in place can

use SAP NetWeaver Single Sign-On, which cre-

ates short-lived certificates in the user’s certificate

store to enable SSO to SAP NetWeaver Gateway.

Note that, when using SAP NetWeaver Single

Sign-On, users have to be authenticated against

the SSO infrastructure of the secure login com-

ponent. This authentication can be performed

seamlessly by reusing the user’s Windows login

credentials. The secure login server issues a client

certificate that it pushes to the Windows Certifi-

cate Store; this certificate can then be used for SSO

to SAP NetWeaver Gateway.

3 SAP NetWeaver Single Sign-On allows users to assign
identity credentials that support single sign-on mechanisms.
The solution is not, however, a panacea to all single sign-on
needs; rather it enables a variety of authentication scenarios.

SAP Logon Tickets
When using logon tickets for authentication, a

user’s ticket is stored as a non-persistent cookie

in the user’s web browser. This cookie contains

the username; therefore to ensure security, we

recommend that you protect the web client’s

cookie cache and employ transport layer security

mechanisms, such as secure socket layer (SSL).

Basic Authentication
Basic authentication is the simplest form of

authentication. In this case, the consumer appli-

cation simply provides a user name and password

when making a request to SAP NetWeaver Gate-

way. Using basic authentication is generally

not recommended for authentication to SAP

NetWeaver Gateway, since it does not support

SSO, and requires the consuming application to

provide secure storage for the login credentials

and handle initial and expired passwords.

This option is also risky because users can be

locked out due to distributed denial-of-service

(DDoS) attacks. Basic authentication is a valid

option in a business-to-consumer scenario in which

a web server connects to SAP NetWeaver Gateway

on behalf of all service users. In this scenario, the

user’s credentials would be known only to the call-

ing web server rather than to the end users.

So when does it make sense to use which

authentication option with SAP NetWeaver

Gateway? Let’s take a look.

Choosing the Right Option
for Authentication
Choosing the appropriate authentication option

for your company depends on your particular

SAP NetWeaver Gateway scenario. Figure 1 on

the next page summarizes which authentication

SSO offers an array of benefits in an environment that uses

SAP NetWeaver Gateway. A user only needs to remember a

single set of credentials, regardless of the UI, which helps increase

productivity. SSO also means that all authentication-related

information is centralized on a single security service provider,

which helps enterprise administrators enforce a consistent

authentication policy throughout the identity management process.

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options SAP NetWeaver Gateway supports, and

which are recommended (shaded in green), for

some of the most common scenarios.

Web Applications
In this scenario, the consumer is any client-

side web application that is based on HTML5,

Silverlight, or Flex, and accesses the service

that exposes the back-end SAP data on the SAP

NetWeaver Gateway server directly from the

user’s browser. Since the application runs in

the browser, it can leverage the authentication

options that are available for browser-based

access out of the box (basic authentication, X.509

client certificate authentication, and browser-

based SAML 2.0 authentication).

While all of the authentication options are sup-

ported in this scenario, the recommended option

for SSO with SAP NetWeaver Gateway in this case

is browser-based SAML 2.0 authentication. In

contrast to X.509 client certificate authentication,

no certificates need to be distributed to the user

environment by a PKI or other software solution,

and unlike basic authentication, there is no risk

of users being locked out due to a DDoS attack.

SAML 2.0 is also suitable for kiosk scenarios

because it can use various authentication options

simultaneously. For example, SAML can use an IdP

(such as Microsoft Active Directory Federation

Services or SAP NetWeaver SSO) and leverage

the user’s Windows domain username and pass-

word to enable smoother SSO. SAP logon tickets

are the method of choice if the web application is

published via SAP NetWeaver Portal.

Desktop Applications
Client-side desktop applications typically run on

an employee’s desktop in the company intranet,

and development platforms can include, among

others, .NET and Java. The most logical approach

to achieving SSO in a client-side environment is

to leverage the initial authentication when a user

logs on to the corporate network, because the user

only has to remember one password. In most cases,

this will be Windows domain user authentication,

which uses Kerberos. SAP NetWeaver Gate-

way currently does not support Kerberos-based

authentication out of the box (future releases

could change that; see sidebar), but the user can

acquire tokens from the initial authentication

that SAP NetWeaver Gateway accepts for login.

You can choose browser-based SAML 2.0

authentication if the IdP supports Kerberos-

based authentication, which is the case for SAP

NetWeaver Single Sign-On and Microsoft Active

Directory Federation Services. Strictly speaking,

however, browser-based SAML 2.0 authentication

is supported only for applications that run inside

a browser and perform redirects, handle cookies,

and manage security sessions. To use browser-

based SAML 2.0 authentication, the client code

for the desktop application needs to ensure that

it behaves like a browser when handling HTTP

redirects, managing forms, and processing cook-

ies. With the upcoming support of OAuth (see

sidebar), this will no longer be necessary.

From a developer’s perspective, it is more

straightforward to use X.509. However the use of

X.509 requires that certificates be rolled out using

either a PKI infrastructure or the secure login

component of SAP NetWeaver Single Sign-On if

there is no PKI in place.

Mobile Applications
Managing the vast array of mobile devices

and applications throughout an enterprise is a

challenge. But mobile enterprise application plat-

forms, such as Sybase Unwired Platform, make it

easy to quickly develop and deploy mobile solu-

tions across the mobile workforce.

With Sybase Unwired Platform, which is lev-

eraged by new mobile applications such as SAP

Consumer
Basic

authentication
SAP logon tickets

X.509 client certificate
authentication

Browser-based SAML 2.0
authentication

Web application (HTML5/
Silverlight/Flex) (When published via

SAP NetWeaver Portal)

Desktop application
(.NET/Java)

Mobile application
(When running on Sybase

Unwired Platform)
(When not running on

Sybase Unwired Platform)

FIGURE 1  Authentication

options in SAP NetWeaver

Gateway (recommended

options are shaded in green)

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