Francois Lascelles

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Top Stories by Francois Lascelles

SOA Best Practices Digest Although certain RESTful web services are of a ‘public’ nature and do not have specific security requirements such as authentication and authorization, any service that has an entry point from an untrusted network is subject to attack and proper threat protection measures are always an essential consideration. RESTful web services are closely aligned to the web itself and as such inherit all traditional threats from the web. Although network level threats are well understood and addressed by traditional firewall infrastructure, RESTful web services type APIs are also subject to content (or message) level threats. For example, consider APIs where XML payloads are POSTed and/or PUT from external requesters. A particularly dangerous threat was uncovered last summer involving a vulnerability in most XML parsing libraries used at the time. An... (more)

REST JSON to SOAP Conversion Tutorial

I often get asked about ‘REST to SOAP’ transformation use cases these days. Using an SOA gateway like SecureSpan to perform this type of transformation at runtime is trivial to setup. With SecureSpan in front of any existing web service (in the DMZ for example), you can virtualize a REST version of this same service. Using an example, here is a description of the steps to perform this conversion. Imagine the geoloc web service for recording geographical locations. It has two methods, one for setting a location and one for getting a location. See below what this would look like i... (more)

WS Security Performance

The WS Secure Conversation specification describes a mechanism letting multiple parties establish a context (using the WS Trust Request Security Token standard) and secure subsequent SOAP exchanges. Each WS Secure Conversation session has an associated shared secret. Instead of using this shared secret directly to sign and encrypt the conversation's messages, symmetric keys are derived from the secret itself. Deriving new keys for each message and different keys for signature and encryption limits the amount of data that an attacker can analyze in attempting to compromise the con... (more)

JSON Schema Validation for RESTful Web Services

In the article "The importance of threat protection for restful web services", I presented a number of content-based threats for XML. When protecting an endpoint from XML based attacks, not only are payloads scanned for code injections, malicious entity declarations and parser attacks, XML documents are actually validated against strict schemas that clearly describe expected document structures. Enforcing this type of compliance at the edge, in a SOA gateway for example, minimizes the risk of attacks of the Web service endpoint. Structure definition languages such as XML Schema ... (more)

Flexible Identity Federation XML Gateways to The Rescue

Imagine a fresh business relationship between ACME Corporation and Partner. As a result of this relationship, ACME wants to grant Partner limited access to one of its core internal applications. They do this, naturally, by exposing a Web service. Why Identity Federation? Boris (an employee at Partner) sends a SOAP request to the ACME Web service along with some password or proof-of-possession type credentials. Because Boris's identity is managed outside of ACME, those credentials cannot be authenticated using ACME's authentication infrastructure. To circumvent this issue, one cou... (more)