When WAFs Go Wrong

Although web application firewalls (WAFs) are an established staple of enterprise application security strategies, the fact is that most organizations struggle to get the most out of them. 

A new survey out last week indicates that a significant number of web application attacks bypass the WAF, organizations struggle to tune them, and they're not well-integrated into broader security functions. This only serves to bolster warnings made by analysts and other studies over the past 18 months that WAF protection mechanisms need to evolve and can't be the only mainstay for an AppSec program.

The latest study comes by way of Neustar International Security Council, which found four in 10 security professionals reported that at least half of application-layer attacks lobbied against them end up bypassing the WAF. A shocking one in 10 said it's more like 90% of attacks cruising by WAF defenses. 

Meanwhile, one in three security pros said some 50% of network requests made in the past 12 months have been labeled as false positive. That matches up with the study's findings that a similar proportion of organizations are finding it hard to appropriately tune their WAFs. Approximately 30% reported they have difficulty altering WAF policies to guard against new application-layer threats. Furthermore, 40% of organizations are unable to fully integrate their WAFs into other application security or broader security functions. 

These results echo a 2019 study conducted by Ponemon Institute that showed 60% of organizations were dissatisfied with their WAFs. That study similarly found organizations battling with a significant percentage of application-layer attacks bypassing the WAF, as well as administrative struggles from the burden of tuning and false positives. Ponemon Institute found the average organization employed 2.5 security administrators, who spent 45 hours per week processing WAF alerts and an additional 16 hours per week writing new rules for the WAF.

What WAFs Aren't Catching
The issues dug up by these studies has definitely hit the radar at analyst firms, which are indicating that the WAF market is due for some considerable shake-ups in the near future. 

"Organizations want more from their WAF providers — and the degree of negative feedback from vendor-supplied references warns that, unless vendors adapt quickly, the WAF market is ripe for disruption," according to Sandy Carielli, principal analyst at Forrester Research, who led the firm's most recent market research on the WAF market this spring.

The Forrester report shows that organizations are particularly struggling as their current WAF deployments are unable to handle a broader range of application attacks, particularly client-side attacks, API-based attacks, and bot-driven attacks.

On the API (application programming interface) front, for example, an increasing number of server-side request forgery (SSRF) are made possible due to how cloud architectures use metadata APIs and webhooks.

"The WAF may not necessarily be deployed in-line to monitor the outbound HTTP requests made by the web application. Many SaaS companies offer some form of web hook product which makes an http request on behalf of the user and cannot be easily differentiated from an SSRF attack," explained Jayant Shukla, CTO and co-founder of K2 Cyber Security, in an analysis earlier this year of the 2019 Capital One breach, which started with an SSRF attack that took advantage in a weakness in the organization's WAF. "These factors expose the fundamental limitations faced by WAFs in trying to defend against SSRF attacks."

The AppSec Wounds Showing Through WAF Band-Aids
Many experts believe the struggles with WAFs indicate more systemic weaknesses in AppSec strategy and execution. For example, a study out from Radware last fall surmised that WAFs are one of several products, such as RASP and code review products, that constitute a "spaghetti-on-the-wall" approach where organizations are throwing product at a problem that requires a more fundamental change in how organizations develop and remediate software. 

For many years, an increasing number of organizations have used WAFs as a stand-in for having a working AppSec program that works on continuously improving the security posture of software based on risk-driven prioritization. Rather than using a WAF as a backstop as improvements are made, they put it as a frontline defense measure. The problem is — as the Neustar and Ponemon studies show — a WAF hamstrung by how quickly the team can create rules to thwart new attack techniques. 

At the end of the day, the dissatisfaction with WAFs may be that many organizations are simply pinning too many of their hopes on them. Instead, some experts say it should simply be seen as a speed bump for attackers while an organization works on actually fixing code.

"If you're going to use a WAF, you won't be protecting your products from attack indefinitely," said Tim Jarrett, senior director of product management of Veracode. "So use the time a WAF gives you wisely; figure out where the underlying vulnerabilities are in your application and fix them." 

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