The importance of threat protection for RESTful web services

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. Any REST web service using those XML parsing libraries could have easily been crippled. In fact, I would expect many deployments out there still using vulnerable versions of those XML parsers today.

Despite fixes applied to parsing libraries to address such vulnerabilities, many potential content-level attacks continue to pose a threat. Consider for example external entity attacks, where a parser is tricked into resolving a resource from a malicious source. Also, SQL injections which were recently at the center of the largest data breach in US history . Many other threats specifically targeting XML enabled services exist such as recursive payloads, schema poisoning and coercive parsing to name a few.

Of course, REST is not bound to XML only. Threat protection for RESTful web services has to potentially consider a number of other content-type specific threats such as for JSON.

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3 Responses to The importance of threat protection for RESTful web services

  1. Janice Gaines says:

    Anyone else here reading “I.T. WARS”? I had to read parts of this book as part of my employee orientation at a new job. The book talks about a whole new culture as being necessary – an eCulture – for a true understanding of security, being that most identity/data breaches are due to simple human errors. It has a great chapter on security. Just Google “IT WARS” – check out a couple links down and read the interview with the author David Scott. (Full title is “I.T. WARS: Managing the Business-Technology Weave in the New Millennium”).

  2. [...] Naturally, I’m concerned about REST-born threats, so I will configure the code injection assertion to scan for all the usual suspects. This can be tuned so that it’s not doing unnecessary work that might affect performance in a very high volume situation: [...]

  3. [...] Schema validation for RESTful Web services In 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 [...]

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