Off to the WAF races

PCI DSS called for implementation of code reviews and web-application firewalls (WAF’s) in order to continue compliance and fight off the Breach Boogieman. Organizations can also conduct code reviews, as outlined in section 6.

Some ‘experts’ believe the web firewalls are just another piece of technology being thrown on the bonfire, while others believe you will never find all the potential bugs and flaws in an organization’s custom code, let-alone commercial software.

Interestingly, there continue to be heated discussions debating the usefulness of WAF’s, where they have to be deployed, what they are supposed to inspect, and whether businesses should be distracted by WAF’s in the first place.  The most important aspect of all this is the functionality that is to be provided by this technology. The WAF requirements outlined in requirement 6.6:

  • Verify that an application-layer firewall is in place in front of web-facing applications to detect and prevent web-based attacks.

Make sure any WAF implementation meets the full extent of the requirement because “detect and prevent web-based attacks” can get a little sticky. As technology goes, there are a few variations in how WAF’s have been developed. Some products use reverse proxying to interrupt the web session for the ‘detect’ and accomplish the ‘prevent’ by only allowing valid sessions. This validation is being done in variations just like typical IDS/IPS’s operation: you get your choice of signatures, anomaly detection, protocol inspection, and combinations thereof. Some of the available products skip the proxy function and monitor the web traffic like a traditional IDS/IPS for known or suspicious threats either in-line or via a SPAN or TAP. Companies can not only choose their type of technology but can also decide on using open-source software or commercially supported products or a cross between the two.

The open-source route offers mod_security for apache and if companies need commercial support, you can get an appliance running mod_security. I found it interesting, in a recent Oracle Application deployment, Oracle recommends the use of mod_security to service as an application-layer firewall and URL-filtering firewall for DMZ-deployments. If mod_security doesn’t fit your needs, Guardian is also an open-sourced software with detection and prevention capabilities. Both have commercial support and product options.

mod_security has some other interesting options. It is possible to take the SNORT web signatures and convert them to mod_security rules via a script provided with mod_security. There are also several groups that provide signatures / rules for mod_security to identity new threats.

Outside the open-source space, there are products like Imperva’s SecureSphere gateways that use anomaly detection and profiling to determine whether something should or should not be allowed to access a web server. This company’s product line features an interesting twist, the dynamic profiling technology relied upon to ‘detect and prevent’ comes from none other than the man that developed ‘stateful packet inspection’ in CheckPoint firewalls.

Along with Imperva, are F5, Cisco, CheckPoint, and the usual list of security vendors ready to snatch up your “bail-out” funding 🙂 . As with any security technology, only after a review of your organizations needs and a thorough pilot of the prospective technology will identify the best-fit for any organization.

At the end of the day, the use of WAF technology to mitigate web application security is but one of the many defenses an organization should have in place to provide data security and data privacy.

What do you use to guard the security of your web applications?

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Posted on May 7, 2009, in Security / Risk, Security Management and tagged , , , , . Bookmark the permalink. Leave a comment.

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