NAXSI – Open-Source WAF For Nginx


NAXSI is an open-source WAF for Nginx (Web Application Firewall) which by default can block 99% of known patterns involved in website vulnerabilities. NAXSI means Nginx Anti XSS & SQL Injection

NAXSI - Open-Source WAF For Nginx

Technically, it is a third party Nginx module, available as a package for many UNIX-like platforms. This module, by default, reads a small subset of simple (and readable) rules containing 99% of known patterns involved in websites vulnerabilities. For example, <, | or drop are not supposed to be part of a URI.

Being very simple, those patterns may match legitimate queries, it is NAXSI's administrator duty to add specific rules that will whitelist those legitimate behaviours. The administrator can either add whitelists manually by analyzing Nginx's error log, or (recommended) start the project by an intensive auto-learning phase that will automatically generate whitelisting rules regarding website's behaviour.


In short, NAXSI behaves like a DROP-by-default firewall, the only job needed is to add required ACCEPT rules for the target website to work properly. I love Nginx and use it for everything, so having a bit of extra protection for it, without too much hassle is great.

Why is it Different?

On the contrary of most Web Application Firewall, Naxsi doesn't rely on a signature base, like an antivirus, and thus cannot be circumvented by an "unknown" attack pattern. Another main difference between NAXSI and other WAF, NAXSI filters only GET and POST resquests, is a Free software (as in freedom) and free (as in free beer) to use.

Do note though, this model requires a bit more effort as you have to whitelist to get things to work but it will block more obfuscated and uncommon attacks without updates or modifications.

You can download the latest version of the module source code here:

naxsi-0.54.zip

But it's most easily installed with an optional distro friendly NAXSI included version of Nginx, which you just need to tweak the config for. On Ubuntu systems for example you'd just do:

One downside of this is you won't get the newest version of NAXSI (or most likely the latest Nginx either) but it will be stable. As Nginx doesn't support runtime module loading you can't update NAXSI outside of recompiling Nginx (not ideal).

You can also read more here.

Posted in: Countermeasures, Security Software

,


Latest Posts:


ZigDiggity - ZigBee Hacking Toolkit ZigDiggity – ZigBee Hacking Toolkit
ZigDiggity a ZigBee Hacking Toolkit is a Python-based IoT (Internet of Things) penetration testing framework targeting the ZigBee smart home protocol.
RandIP - Network Mapper To Find Servers RandIP – Network Mapper To Find Servers
RandIP is a nim-based network mapper application that generates random IP addresses and uses sockets to test whether the connection is valid or not with additional tests for Telnet and SSH.
Nipe - Make Tor Default Gateway For Network Nipe – Make Tor Default Gateway For Network
Nipe is a Perl script to make Tor default gateway for network, this script enables you to directly route all your traffic from your computer to the Tor network.
Mosca - Manual Static Analysis Tool To Find Bugs Mosca – Manual Static Analysis Tool To Find Bugs
Mosca is a manual static analysis tool written in C designed to find bugs in the code before it is compiled, much like a grep unix command.
Slurp - Amazon AWS S3 Bucket Enumerator Slurp – Amazon AWS S3 Bucket Enumerator
Slurp is a blackbox/whitebox S3 bucket enumerator written in Go that can use a permutations list to scan externally or an AWS API to scan internally.
US Government Cyber Security Still Inadequate US Government Cyber Security Still Inadequate
Surprise, surprise, surprise - an internal audit of the US Government cyber security situation has uncovered widespread weaknesses, legacy systems and poor adoption of cyber controls and tooling.


2 Responses to NAXSI – Open-Source WAF For Nginx

  1. Vladimir Smitka March 22, 2016 at 2:30 pm #

    Nginx 1.9.11 and newer supports runtime module loading ;-)

    https://www.nginx.com/blog/dynamic-modules-nginx-1-9-11/

    • Darknet March 22, 2016 at 5:09 pm #

      Oh nice, no wonder the separate nginx-nasxi package isn’t going to be supported any more. Current Ubuntu LTS version is only at nginx 1.4.6 tho – so a fair way behind.