ModSecurity and owasp-modsecurity-crs about

Hi all,

First we need to know Web Application Firewall (WAF) :

A web application firewall (WAF) is an application firewall for HTTP applications. It applies a set of rules to an HTTP conversation. Generally, these rules cover common attacks such as cross-site scripting (XSS) and SQL injection.

While proxies generally protect clients, WAFs protect servers. A WAF is deployed to protect a specific web application or set of web applications. A WAF can be considered a reverse proxy.

WAFs may come in the form of an appliance, server plugin, or filter, and may be customized to an application. The effort to perform this customization can be significant and needs to be maintained as the application is modified.

What is a Web Application Firewall (WAF)?

A WAF or Web Application Firewall helps protect web applications by filtering and monitoring HTTP traffic between a web application and the Internet. It typically protects web applications from attacks such as cross-site forgery, cross-site-scripting (XSS), file inclusion, and SQL injection, among others. A WAF is a protocol layer 7 defense (in the OSI model), and is not designed to defend against all types of attacks. This method of attack mitigation is usually part of a suite of tools which together create a holistic defense against a range of attack vectors.

By deploying a WAF in front of a web application, a shield is placed between the web application and the Internet. While a proxy server protects a client machine’s identity by using an intermediary, a WAF is a type of reverse-proxy, protecting the server from exposure by having clients pass through the WAF before reaching the server.

A WAF operates through a set of rules often called policies. These policies aim to protect against vulnerabilities in the application by filtering out malicious traffic. The value of a WAF comes in part from the speed and ease with which policy modification can be implemented, allowing for faster response to varying attack vectors; during a DDoS attack, rate limiting can be quickly implemented by modifying WAF policies.

What is the difference between blacklist and whitelist WAFs?

A WAF that operates based on a blacklist (negative security model) protects against known attacks. Think of a blacklist WAF as a club bouncer instructed to deny admittance to guests who don’t meet the dress code. Conversely, a WAF based on a whitelist (positive security model) only admits traffic that has been pre-approved. This is like the bouncer at an exclusive party, he or she only admits people who are on the list. Both blacklists and whitelists have their advantages and drawbacks, which is why many WAFs offer a hybrid security model, which implements both.

What are network-based, host-based, and cloud-based WAFs?

A WAF can be implemented one of three different ways, each with it’s own benefits and shortcomings:

• A network-based WAF is generally hardware-based. Since they are installed locally they minimize latency, but network-based WAFs are the most expensive option and also require the storage and maintenance of physical equipment.
• A host-based WAF may be fully integrated into an application’s software. This solution is less expensive than a network-based WAF and offers more customizability. The downside of a host-based WAF is the consumption of local server resources, implementation complexity, and maintenance costs. These components typically require engineering time, and may be costly.
• Cloud-based WAFs offer an affordable option that is very easy to implement; they usually offer a turnkey installation that is as simple as a change in DNS to redirect traffic. Cloud-based WAFs also have a minimal upfront cost, as users pay monthly or annually for security as a service. Cloud-based WAFs can also offer a solution that is consistently updated to protect against the newest threats without any additional work or cost on the user’s end. The drawback of a cloud-based WAF is that users hand over the responsibility to a third-party, therefore some features of the WAF may be a black box to them. Learn about Cloudflare’s cloud-based WAF solution.

Now, one of the awesome WAFs is ModSecurity.

SpiderLabs/ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx that is developed by Trustwave’s SpiderLabs. It has a robust event-based programming language which provides protection from a range of attacks against web applications and allows for HTTP traffic monitoring, logging and real-time analys…

The OWASP Foundation came online on December 1st, 2001 it was established as a not-for-profit charitable organization in the United States on April 21, 2004, to ensure the ongoing availability and support for our work at OWASP. OWASP is an international organization and the OWASP Foundation supports OWASP efforts around the world. OWASP is an open community dedicated to enabling organizations to conceive, develop, acquire, operate, and maintain applications that can be trusted. All of the OWASP tools, documents, forums, and chapters are free and open to anyone interested in improving application security. We advocate approaching application security as a people, process, and technology problem because the most effective approaches to application security include improvements in all of these areas. We can be found at www.owasp.org.

SpiderLabs/owasp-modsecurity-crs is here.

OWASP ModSecurity Core Rule Set (CRS) Project (Official Repository)

some of the rules

REQUEST-900-EXCLUSION-RULES-BEFORE-CRS.conf.example
REQUEST-901-INITIALIZATION.conf
REQUEST-903.9001-DRUPAL-EXCLUSION-RULES.conf
REQUEST-903.9002-WORDPRESS-EXCLUSION-RULES.conf
REQUEST-903.9003-NEXTCLOUD-EXCLUSION-RULES.conf
REQUEST-903.9004-DOKUWIKI-EXCLUSION-RULES.conf
REQUEST-903.9005-CPANEL-EXCLUSION-RULES.conf
REQUEST-903.9006-XENFORO-EXCLUSION-RULES.conf
REQUEST-905-COMMON-EXCEPTIONS.conf
REQUEST-910-IP-REPUTATION.conf
REQUEST-911-METHOD-ENFORCEMENT.conf
REQUEST-912-DOS-PROTECTION.conf
REQUEST-913-SCANNER-DETECTION.conf
REQUEST-920-PROTOCOL-ENFORCEMENT.conf
REQUEST-921-PROTOCOL-ATTACK.conf
REQUEST-930-APPLICATION-ATTACK-LFI.conf
REQUEST-931-APPLICATION-ATTACK-RFI.conf
REQUEST-932-APPLICATION-ATTACK-RCE.conf
REQUEST-933-APPLICATION-ATTACK-PHP.conf
REQUEST-934-APPLICATION-ATTACK-NODEJS.conf
REQUEST-941-APPLICATION-ATTACK-XSS.conf
REQUEST-942-APPLICATION-ATTACK-SQLI.conf
REQUEST-943-APPLICATION-ATTACK-SESSION-FIXATION.conf
REQUEST-944-APPLICATION-ATTACK-JAVA.conf
REQUEST-949-BLOCKING-EVALUATION.conf
RESPONSE-950-DATA-LEAKAGES.conf
RESPONSE-951-DATA-LEAKAGES-SQL.conf
RESPONSE-952-DATA-LEAKAGES-JAVA.conf
RESPONSE-953-DATA-LEAKAGES-PHP.conf
RESPONSE-954-DATA-LEAKAGES-IIS.conf
RESPONSE-959-BLOCKING-EVALUATION.conf
RESPONSE-980-CORRELATION.conf

“Anomaly Scoring Mode” etc. all in theese rules…

if you get an error with

tail -f error.log

Inbound Anomaly Score Exceeded (Total Inbound Score: 5 — SQLI=0,XSS=0,RFI=0,LFI=0,RCE=5,PHPI=0,HTTP=0,SESS=0): Remote Command Execution: Unix Shell Expression Found”] [tag “event-correlation”]

maybe you can try

SecRuleRemoveById JustWriteIDHereYouWantRuleToRemoveLike900004

Good Luck!