Early Blocking is a feature that CRS will deliver with the next major release, probably Spring 2022. You can use it immediately when deploying the latest dev / nightly build. This blog post will explain the feature, how to enable it and why it is very useful. What is Early Blocking? ModSecurity, the engine below CRS, processes requests in multiple phases. The phase 1 is the request header phase, the phase 2 is the request body phase.
In one of my previous blog posts, I introduced the CRS plugin mechanism that we are rolling out for the next major release. Check out the blog post to learn how you can start using plugins immediately, without waiting for the next release (hint: really simple). Several plugins are already available. One of them is the Fake Bot Plugin that I put into production recently. It’s a neat little plugin written by CRS dev Azurit / Jozef Sudolsky and it can serve as a perfect illustration of the capabilities of CRS plugins.
The log4j mess allowed everybody to see security shortcomings of the IT industry on a big scale. It also shed light on the shortcomings of the WAF market, a highly contested field with a myriad of commercial players and - well - us, the OWASP ModSecurity Core Rule Set (CRS), the only general purpose open source Web Application Firewall option. This blog post will describe the WAF market from a CRS perspective, it will explain what we see as lacking and how we plan to improve the situation.
Plugins are not part of the CRS 3.3.x release line. They will be released officially with the next major CRS release 4.x. In the meantime, you can use them with one of the stable releases by following the instructions below. What are Plugins? Plugins are sets of additional rules that you can plug in to your web application firewall in order to expand CRS with complementary functionality or to interact with CRS.
It’s time to talk about the ModSecurity engine and to introduce you to Coraza, a new contender on the WAF front. Any rule set is nothing without a WAF engine to run it, so even if our project is focused on the rules, we need to look at the underlying engine(s) from time to time. On August 26, 2021, Trustwave, the owner of ModSecurity, announced the end of Support for ModSecurity for 2024 in a blog post.
We have been updating our detection for the infamous CVE-2021-44228 vulnerability and its siblings for several days now. With the new experimental rule 1005, we think we really have decent detection capabilities now. Read up on this development in the separate blog post CRS and Log4j / Log4Shell / CVE-2021-44228. Right before the log4j CVE was published, we took up our CRS Sandbox that lets you test payloads against various CRS installations.
This is an evolving blog post with infos about the role of CRS in defending against the log4j vulnerabilities that threatens quite all logging JAVA applications. We believe the mitigations and rules suggested below will have you covered up to and including CVE-2021-45105. In January 2022, we have consolidated our knowledge into a pull request with new rules to be merged into CRS for the next major release. The pull request can be applied to your existing installation for immediate use of the new rules.
The OWASP ModSecurity Core Rule Set project is very happy to present the CRS Sandbox. It’s an API that allows you to test an attack payload against CRS without the need to install a ModSecurity box or anything. Here is how to do this: $ curl -H “x-format-output: txt-matched-rules” “
The OWASP ModSecurity Core Rule Set team met for a one week developer retreat in the Swiss mountains to hack away at CRS together. We worked on several larger projects and ran seven additional workshops, all documented on our GitHub wiki. Why Switzerland? Switzerland is an expensive place, but most of our active developers live in Europe and then Switzerland becomes central. And we found the Hacking Villa ran by local ISP Ungleich.
Paranoia Levels are an essential concept when working with the Core Rule Set. This blog post will explain the concept behind Paranoia Levels and how you can work with them on a practical level. Introduction to Paranoia Levels In essence, the Paranoia Level (PL) allows you to define how aggressive the Core Rule Set is. Very often, I explain this with the help of a dog. In the default installation, you get a family dog that is really easy going.