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Web Application Security: We Need Web Application Firewalls To Work. Better.

By Rich

Jeremiah Grossman is just finishing up his keynote at the SANS conference on web application security. Jeremiah and I have talked a few times about the future of web application security, and we both agree that many current approaches just can’t solve the problem. It’s increasingly clear that no matter how good we are at secure programming (SDLC) , and no matter how effective our code scanning and vulnerability analysis tools are, neither approach can “solve” our web application security problem.

We not only develop code at a staggering pace, we have a massive legacy code base. While many leading organizations follow secure software development lifecycles, and many more will be adopting at least some level of code scanning over the next few years thanks to PCI 6.6, it’s naive to think that even the majority of software will go through secure development any time soon. On top of that, we are constantly discovering new vulnerability classes that affect every bit of code written in the past. And, truth be told, no tool will ever catch everything, and even well-educated people still make mistakes.

Since these same issues affect non-web software, we’ve developed some reasonably effective ways to protect ourselves on that side. The key mantra is shield and patch. When we discover a new vulnerability, we (if possible) shield ourselves through firewalls and other perimeter techniques to buy us time to fix (patch) the underlying problem. No, it doesn’t always work and we still have a heck of a lot of progress to make, but it is a fundamentally sound approach.

We’re not really doing this much in the web application world. The web application firewall (WAF) market is growing, but has struggled for years. Even when WAFs are deployed, they still struggle to provide effective security. If you think about it, this is one big difference between a WAF and a traditional firewall or IPS. With old school vulnerabilities we know the details of the specific vulnerability and (usually) exploit mechanism. With WAFs, we are trying to block vulnerability classes instead of specific vulnerabilitie s . This is a HUGE difference. The WAF doesn’t know the details of the application or any application-specific vulnerabilities, and thus is much more limited in what it can block.

I don’t think stand-alone external WAFs will ever be effective enough to provide us the security we need for web applications. Rather, we need to change how we view WAFs. They can no longer be merely external boxes protecting against generic vulnerabilities; they need tighter integration into our applications. In the long term, I’ve branded this Application and Database Monitoring and Protection (ADMP) as we create a dedicated application and database security stack that links from the browser on the front end, to the DB server on the back.

There are a few companies exploring these new approaches today. Jeremiah’s company, WhiteHat Security, has teamed up with F5 to provide specific vulnerability data from a web application to the F5 WAF. Fortify is moving down the anti-exploitation path with real-time blocking (and other actions) directly on the web application server. Imperva is tying together their WAF and database activity monitoring. (I’m sure there are more, but these are the web-application specific companies taking this path I can remember offhand). They are all taking different approaches, but all recognize that “static” WAFs or code scanning alone are pretty limited.

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WAFs, DB sec, and packaged app sec are different customers, processes, infrastructure components, etc.  The functions will indeed collapse, but are far more likely to do so into classes that share a common buyer, have technical synergy, are deployed in a similar location / technical function, etc.  WAFs into a next-gen firewall?  Sure.  They’‘re both gateway / perimeter-oriented enforcement points, decide what gets in, are bought by the same buyer to support a common process.  WAFs into Db sec?  Different part of the infrastructure, different buyer, related but substantially different process (ex. audit).  Crossing these boundaries is possible only by the very large (ex. IBM) or industry standards.

By Ted J


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