There is no doubt in my mind that some very strong experts out there have put WAF or WAF-like technology to good use. However, WAF is dead and dying regardless.
I think that very large-installation, Internet-facing web applications require Anti-DDoS technology in the form of an appliance, preferably one that does rate-based behavior detection. I often feel that those same organizations also require SLB appliances, although I prefer to see these integrated with a switch fabric in a chassis-based, large backplane network switch. In a year’s time, SLB Layer-2 technology could be replaced by VMware DRS clustering and/or an equivalent like Microsoft PRO. I was always a fan of Anycast to replace SLB at Layer-3. I continue to suggest these models/architectures today.
Can whitelist WAF technology be used by those same devices in the short-term (Anti-DDoS or SLB appliance)? Absolutely, as long as it’s done by an expert and tuned to the applications. Should these devices sometimes be separated out of a traditional operational role, due to auditability and for compliance scoping purposes? Probably not. Should they perform monitoring, debugging capability, or solving hard production problems? Probably not.
The reason that the first question is a yes, and the others are a no is because Anti-DDoS and SLB devices are already performance-ready-capable of providing WAF whitelisting functionality (note: not in all cases, but this works especially well for devices that provide rate-based behavior detection before mitigation). Monitoring does NOT require an inline device. All it requires is network taps (or potentially port-mirroring, but most professionals recommend taps over SPAN ports). Also, infrastructure is changing rapidly, so it’s not wise to invest in a dying model.
Additionally, I know that companies like Sourcefire and Reflex Systems are integrating at the VMsafe API layer, which is a hypervisor introspection layer much like XenAccess. This is really where much of the AV/IDS/IPS/HIMS/DLP/WAF/blacklisting-whitelisting technology belongs. VNET will also change the introspection layer (in addition to almost completely eliminating the physical network layer and SIM/SEM/SIEM/NMS/EMS moves & changes), as it simply adds to introspection functionality. I have already alluded to Cisco AXG becoming a VNET “module”, but what if Reflex Systems or StoneSoft start integrating WAF not only as a VNSS (Virtual Network Security System), but also at the hypervisor introspection layer?
Fortunately, for application security, server virtualization and the evolutions it’s bringing with it e.g VNET and VMsafe, are going to dominate traditional networks and cut their existing budgets. Unfortunately for application security, the new virtualization evolution also brings with it tons of object reuse (there are at least two new controls channels available to adversaries), and new ways of establishing covert channels.
This means a few things. First of all, the word “firewall” is dead, and therefore, the word “web application firewall” and the associated acronym, WAF, are also dead. Imagine today if there existed a control channel that, when taken over by adversaries, it became a covert channel that had unlimited object reuse control of every physical RAM on every computer in existence all at once. This is cloud computing, but virtualized.
Not only that, but we are saying that adversaries have already bypassed traditional firewalls by using the application layer i.e. Hacking Intranets from Jeremiah Grossman. Thus, this master, covert control channel is already on its way to being built (at least as man-in-the-browser). Imagine for a second that you don’t use NoScript with Firefox and additionally implement the features of Chrome by using multiple Firefox profiles. Imagine for a second that you are a regular user, with all of those Clickjacking and modern application attacks available to anyone who wants to get to you.
Like many of us used the words “brick-and-mortar” to describe backwards-companies during the dotCom bubble, I think “fire-and-wall” well-describes organizations that continue to cling to traditional networks and network security as answers to Internet, Enterprise IT, and any operational risk.
Do I intend to sell you on the idea that we should all instead jump to Fortify RTA or Microsoft SRE? No. There are potential consequences to any of this. This is only the functionality required to reduce risk to applications, not the assurance that risks have been removed.
TCSEC says that we need to balance functionality and assurance. But nobody ever bothered to do any assurance. Assurance is the Microsoft SDL, SDL Pro, and SDL-IT. @Stake and Foundstone are gone and have split into tons of fractured security evaluation and risk assessment boutiques that have 1-300 developer-security-tester guru’s that mix SAST and DAST with expert review.
But the SAST+DAST market is less than $100M, while WAF is at least 20% more than that (although probably inflated).
I hate to be the bearer of bad news, but you don’t just say “DO BOTH” because nobody will do the SAST+DAST work. We tried that last time, when tcp_wrappers and the DEC firewall came about The underground that wanted to keep their covert control channels alive started dumping rootkits on pre-pwned Unix machines. Then Dildog and others made it possible to easily access Windows machines, and after that – botnets and the like have reigned. There are already backdoors in our web applications. OWASP Scrubbr is not going to save us all by itself.
Who did the work back then? OpenBSD? Certainly not Microsoft, and even today their SDL appears to be failing by some, but imagine if it did not exist at all. We obviously have to do better with assurance practices.
Can functionality-based controls work easier, better, and faster than assurance ones? Are they that less complex and easier to train? Or is there just more written about them because it’s easier to SELL them by baking them into products rather than customizing them to an ISV organization or an Enterprise development team?
If you are part of the group that is spending $120M on WAF technology, then you are hurting the SAST+DAST market because you’re taking away that spending. Clearly, risk analysis is not taking place and people are spending based on familiarity in addition to PCI-DSS requirement 6.6, which all but forces the inequality to happen.
Look at the best in exploitation-countermeasure functionality-based controls that work on object reuse problems e.g. DEP, ASLR, SafeSEH, SafeInt, et al. Are adversaries still bypassing these? Security researchers in the offensive-research space are. These countermeasures are closer to the code (even HIPS is closer than network-based IPS), like many WAF suggestions. Is is true that we still require assurance even after 15 years of exploitation-countermeasure optimization? I remember when stack-guard protections were first coming out – they were seen as a huge joke (i.e. toy/researcher technology), much like Fortify RTA, CORE GRASP, Microsoft AntiXSS-SRE/AntiCSRF, GDS Security GPF, and HDIV are seen now.
I know to many of you out there, this looks like a rant, and I really could go on forever about this topic. So, go to the datacenter, give your WAFs a hug, and continue to buy into the “functionality is better than assurance” argument. You’ll feel better in the morning, right after you forget that you just opened up your database to any talented people who want to make money from the data in it.
Also, pen-testing is dead. We no longer need to prove that applications are insecure. We know they’re insecure – no matter how many functionality controls you layer on top of them. Unless YOU prove that the applications that YOU are responsible for ARE secure, you are working against the rights of users, consumers, cardholder data, personally identifiable information tied to healthcare and financial records, trade secrets, and the ability to control our critical infrastructure. Enjoy.
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