Erwin Huber Dohner, head of research and development at Switzerland-based WAF vendor Ergon Informatik, confirmed after seeing Ristic's presentation that the evasion methods are a problem for the industry. Ergon recently identified some similar techniques that worked against its product and have addressed them, he said.

By making his research public, Ristic hopes to kick start a discussion in the industry about protocol-level and other types of evasion. A wiki has also been set up with the purpose of building a freely available catalogue of WAF evasion techniques.

If vendors and security researchers don't document the problems and make them known, WAF developers will make the same mistakes over and over, Ristic said.

In addition, the availability of the testing tool will allow users to discover which WAF products are vulnerable and hopefully force vendors to fix them.

Vendors have different priorities and don't normally fix things unless there's a real risk to their customers, Ristic said. This research project will hopefully generate the necessary incentive for them to deal with these issues, he said.