Jason Macy, CTO
Forum Systems, Inc
Introduction
A common industry misconception is understanding the differences between an XML Gateway and a Web Application Firewall. These technologies are sometimes confused as being competitive, but in fact they are complementary technologies that together provider the foundation of modern-day network perimeter security infrastructure.
Key Areas of Comparison
To better understand the distinctions between these product technologies, the primary areas of comparison are as follows:
Topology
- Deployment Modes
- Standards
- Protocols
- Threat Mitigation
- Transaction Privacy
- Transaction Integrity
- Access Control
- SSO
- Workflow
- Transformation / Mapping
WAF technology has several deployment modes, but it is an important distinction from a gateway product that over 50% of WAF deployments are in non-inline mode, also known as passive mode. The modes of deployment are:
- Non-Inline Mode (50% of deployments)
- Transparent Proxy
- Layer 2 Bridge
- Reverse Proxy
XML Gateway Topology
XML Gateways are always deployed in a reverse-proxy configuration where the gateway component terminates the connection and provides the security, identity, governance, and mediation functions at TCP Layer 4-7. The reverse-proxy deployment paradigm is necessary since XML Gateways serve as a protocol break intermediary for traffic flow and have the ability to restrict and block traffic flow as needed. Thus, the mode of deployment for XML Gateway is always:
- Reverse Proxy
- Service Mode (Request/Response directly to Gateway, which performs the business function)
Protocols and Message Formats
A WAF product focuses on different set of protocols and message formats than an XML Gateway technology product. This follows the logical expectation based on what types of systems and infrastructure these technology products focus on.
A WAF focuses on the following technologies:
WAF Standards
WAF Protocols
- HTTP, HTTPS
- SSL / TLS
XML Gateway technology needs to have a much more comprehensive set of technology standards and formats it supports since it is an inline deployment which requires the need to bridge technology protocols and messaging standards in order to be the "gateway" conduit of message flow.
XML Gateway Standards
- XHTML, XML, SOAP, JSON, AS2, XML-Sec, WS-Sec, WSDL, XSD,
- ebXML, SAML, OAuth, WS-Federation, WS-Trust, XACML
- WS-Addressing, WS-RM, WS-Policy, Xpath, XSLT
XML Gateway Protocols
- HTTP, HTTPS
- SSL / TLS
- JMS (IBM, Tibco, JBoss, Oracle, Active MQ)
- AMQP
- FTP/FTPS
- SFTP
- SMTP
Security
As WAF and XML Gateway products are both security products by trade, there are 3 primary areas of Security that these technology target.
- Threat Mitigation
- Transaction Privacy
- Transaction Integrity
Threat mitigation is the ability to identify, detect, and re-mediate potential threat vectors in the traffic patterns.
A WAF product mostly focuses on HTML and HTTP based traffic paradigms whereby vendor specific static vulnerability patterns can be detected, as well as other aspects of request/response patterns pertaining to HTTP traffic flow. The primary vectors for threat mitigation for WAF technology:
- HTML Content Aware
- Intrusion Detection and Prevention (URI patterns)
- URI rate-based heuristics
- Vendor Vulnerabilities
- URL cloaking / rewrite
- Parameter Inspection
- Learning mode (false positive / false negative behavior modeling)
An XML Gateway performs deep-content inspection and parsing of the messages at the application layer of the message pattern. Since an XML Gateway is a protocol-break intermediary, it consumes the message, inspects the contents, and then re-assembles for sending to the back-end service infrastructure. This puts a much higher technology burden on XML Gateway technology to understand and be able to parse a much broader variety of protocols and message formats as well as ensure adherence to industry messaging standards and formats.
The primary vectors for threat mitigation for XML Gateway technology are:
- XML/SOAP/REST Content Aware
- Intrusion Detection and Prevention (parsing and deep-inspection)
- Rate-based, Size-Based heuristics
- Schema Validation
- Virus detection on XML/SOAP payloads
- URL cloaking / rewrite
- XML Parser Attacks
Security: Transaction Integrity
Threat integrity is the ability to ensure conformance can be verified and tampering has not occurred.
A WAF will target the transaction integrity as it pertains to cookies, jsp files, RFC conformance, and other aspects of HTTP and HTML request/response expectations. The transaction integrity targets of a WAF are:
- Session Tracking
- Cookies, Source/Dest IPs
- HTTP RFC conformance
- HTML Form parameter checking
- Cross-Site Scripting
- Cookie Signing
An XML Gateway deals with more aspects of transaction integrity since it also has to be able to handle cryptography at the message level and be able to process and verify digital signatures and provide conformance checks across a broader spectrum of formats.
XML Gateway transaction integrity features include:
- XML-DSIG, OASIS WS-Security
- Signature Verification
- X509 Path Validation
- DTD Schema Validation
- XSD Schema Validation
- JSON Schema Validation
- HTTP RFC Conformance
- JMS Envelope and Message Conformance
Identity
Identity and Access Control are central requirements for any service-based architecture with consumers and services. It is also essential for portals and other access to information that may be sensitive or controlled. WAF technology generally does not deal with identity, but does have some lightweight features in this area.
The core differences between a WAF and an XML Gateway in this area are broad. A WAF does not have awareness of many of the identity token formats outside of traditional web and HTTP based formats.
WAF: Native Identity Integrations
Active Directory, LDAP, RADIUS
WAF: Protocol Tokens
Basic, Digest, Form Post, SSL X509, NTLM, Kerberos
XML Gateway technology conversely, is heavily dedicated to identity token consumption, generation, authentication, and authorization. By necessity of the deployment and flow control paradigm of XML Gateway technology, the protocol break interception for security and mediation also becomes the logical point of centralizing the identity enforcement and single-sign on functionality.
XML Gateway: Identity Integrations
Active Directory, LDAP, Siteminder, Tivoli AM, ClearTrust, Kerberos KDC, CoreID,
JSAM, WS-Trust, XACML, OAuth
XML Gateway: Message-Based Tokens
WS-Username, WS-Kerberos, WS-X509, SAML, DSIG
XML Gateway: Protocol Tokens
Basic, Digest, Form Post, Cookie, SSL X509, REST URI, NTLM, Kerberos
XML Gateway: Credential Translation
Message-to-Protocol, Protocol-to-Message
XML Gateway: SSO + Federation
Sessions, SAML, STS
Processing, Mediation, and Workflow
An area of stark difference between an XML Gateway and a WAF is in the arena of mediation, transaction manipulation, and workflow routing. This is again a primary difference due to the topology and deployment paradigms. Deploying a WAF in passive mode (over 50% of deployments) does not have any ability to manipulate or alter the traffic data. For the small percentage of WAF deployments that are in-line, the types of traffic that can be manipulated are effectively the HTML variants.
XML Gateway technology is designed specifically to consume the message, parse the message, apply mediation, enrichment, transformations, and finally determine the end-point target based on static or dynamic criteria. Thus, the XML Gateway technology component is often used to perform a wide variety of business functions outside of pure security processing.
For WAF technology, when deployed in in-line mode, the processing and mediation that can be enforced focuses on the following areas:
WAF: Workflow Management
- Allow/Deny
- URL Rewrite
- Compression
- Content Replacement
XML Gateway: Workflow Management
- Attribute Mapping
- Archiving
- Content-Based Routing
- Database Mapping
- Digital Signatures
- Header and Body Identification
- Identity Token Conversion
- Enrichment Data Aggregation
- Encryption
- Node Conversion and Encoding
- Transformation
Complimentary, not Competitive
A robust, resilient, secure architecture starts by ensuring the right technology components are in place. WAF technology serves an essential role in the threat and access control side of web application traffic flows. XML Gateway technology serves an essential role in the security, identity, governance, and mediation of business services, mobile devices, B2B flows, XML, SOAP, and REST messaging patterns with deep-content inspection and business-logic mediation. A WAF and an XML Gateway are fundamental components of a secure, centralized architecture strategy. These technology components focus on the TCP Layer 4-7 aspects of transaction, which comprise a much broader spectrum of the actual information flow across the corporate boundaries.
These components should be deployed where traditional Protocol Firewalls and IDS (Intrusion Detection Systems) are deployed, which provide the TCP Layer 2-3 protection.
Bottom line:
WAF + XML Gateway = Secure Architecture
