Lightbulb – Framework for Auditing Web Applications Firewalls

LightBulb is an open source python framework for auditing web application firewalls and filters. Web Applications Firewalls (WAFs) are fundamental building blocks of modern application security. For example, the PCI standard for organizations handling credit card transactions dictates that any application facing the internet should be either protected by a WAF or successfully pass a code review process.

Lightbulb-framework - Tools for Auditing WAFS
Lightbulb-framework – Tools for Auditing WAFS

Nevertheless, despite their popularity and importance, auditing web application firewalls remains a challenging and complex task. Finding attacks that bypass the firewall usually requires expert domain knowledge for a specific vulnerability class. Thus, penetration testers not armed with this knowledge are left with publicly available lists of attack strings, like the XSS Cheat Sheet, which are usually insufficient for thoroughly evaluating the security of a WAF product.

The framework consists of two main algorithms:

  • GOFA: An active learning algorithm that infers symbolic representations of automata in the standard membership/equivalence query model. Active learning algorithms permits the analysis of filter and sanitizer programs remotely, i.e. given only the ability to query the targeted program and observe the output.
  • SFADiff: A black-box differential testing algorithm based on Symbolic Finite Automata (SFA) learning Finding differences between programs with similar functionality is an important security problem as such differences can be used for fingerprinting or creating evasion attacks against security software like Web Application Firewalls (WAFs) which are designed to detect malicious inputs to web applications.

In case the user looking to have a GUI solution there is an extension for Burp Suite which can be a straightforward to run the testing.

Examples of Basic Functionalities

  • Filter Auditing using GOFA
  • Differential Testing using SFADiff
  • Browser and WAF (Evasion)
  • Browser Filter and WAF (Evasion)
  • MySQL and WAF (Evasion)
  • WAF and WAF (Fingerprint)
  • Browser and Browser (Fingerprint)

You can read more and download this tool over here:

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