Friday, February 1, 2008

Tangible ROI of a Web Application Firewall (WAF)

One of the challenges facing organizations that need to increase the security of their web applications is to concretely provide appropriate "Return On Investment" (ROI) for procurement justification. Organizations can only allocate a finite amount of budget towards security efforts therefore security managers need to be able to justify any commercial services, tools and appliances they want to deploy. As most people who have worked in information security for an extended period of time know, producing tangible ROI for security efforts that address business driver needs is both quite challenging and critically important.

The challenge for security managers is to not focus on the technical intricacies of the latest complex web application vulnerability or attack. C-level Executives do not have the time, and in most instances the desire, to know the nuances of an HTTP Request Smuggling attack. That is what they are paying you for! Security managers need to function as a type of liaison where they can take data from the Subject Matter Experts (SMEs) and then translate that into a business value that is important to the C-level Executive.

One, almost guaranteed, pain point to most executives are vulnerability scan reports that are presented by auditors. The auditors are usually being brought in from and reporting to a higher-level third party (be it OMB in the Government or PCI for Retail). Executives like to see "clean vulnerability scan reports." While this will certainly not guarantee that your web application is 100% secure, it can certainly help to prove the counter-argument. And to make matters worse, nothing is more frustrating to upper Management than auditor reports list repeat vulnerabilities that either never go away or pull the "Houdini" trick (they disappear for awhile only to suddenly reappear). Sidebar - see Jeremiah Grossman's Blog post for examples of this phenomenon. These situations are usually attributed to breakdowns in the Software Development Life Cycle (SDLC) where code updates are too time consuming or the change control processes are poor.

This is one of the best examples of where a Web Application Firewall can prove its ROI.

At Breach Security, we receive many inbound calls from prospects who are interested in WAF technology but are lacking that "Big Stick" that helps convince upper management to actually make the purchase. The best scenario we have found is to suggest a Before and After; comparison of a vulnerability scan report while they are testing the WAF on their network. The idea is to deploy the WAF in block mode and then initiate a rescan of a protected site. The difference in the reduction of findings is an immediate, quantitative ROI.

Here is a real example. One of our current customers followed this exact roadmap and this is a summary (slightly edited to remove sensitive information) of the information they sent back to us:

Our WAF is installed and running. I have tested its impact on and it is operating very admirably. This morning I had the vulnerability scanning team run an on-demand scan to test the efficacy of the appliance, and I was very impressed with the results. Our previous metrics for in the last scan were 64 vulnerabilities, across all outside IP addresses (including,,, etc.) and with the Breach appliance in place, the metric from today's scan was 5 vulnerabilities, with details:

- High vulnerabilities dropped from 38 to 0

- Medium vulnerabilities dropped from 12 to 0

- 1 low vulnerability remains due to simply running a web server (we will eliminate this via exception)

- 1 low vulnerability due to a file/folder naming convention that is typical and attracts unwanted attacks (will be eliminated via rule addition)

Bear in mind that I have applied the appliance with a basic (almost strictly out-of-the-box) configuration and ruleset to protect only ( in the report), and the 35 warnings that remain are for the other websites, and would similarly disappear when protected by the appliance. In my opinion, this was a very successful test that indicates the effectiveness of the appliance.

So, looking at the report after the WAF was in place, the web site removed 38 high and 12 medium vulnerabilities and left only 2 low ones (which are really just informational notices). That is pretty darn good and that was just with the default, generic detection ModSecurity rule set! Hopefully this information has helped to provide a possible use-case testing scenario to show tangible ROI of a WAF.

In a future post, I will discuss how custom WAF rule sets can be implemented to address more complex vulnerability issues identified not by a scanner but by actual people who have performed a web assessment/pentest.

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