Blogs & Stories

SpiderLabs Blog

Attracting more than a half-million annual readers, this is the security community's go-to destination for technical breakdowns of the latest threats, critical vulnerability disclosures and cutting-edge research.

ModSecurity for Java - BETA Testers Needed

Soc-logo-300x200image from www.modsecurity.orgOver the course of the summer of 2013, the ModSecurity team participated in Google's Summer of Code (GSoC) program through OWASP. We helped by mentoring Mihai Pitu who developed a port of ModSecurity for Java!

The main problem this project solves is that you will no longer have to front-end your Java app servers with a reverse proxy in order to gain ModSecurity protections! ModSecurity
standalone code uses JNI to hook into Java servers (Tomcat, Spring, Stuts, etc...) as a Servlet Filter
. We need BETA testers to help us ensure that the code is working properly. Please see the steps below and send us feedback.

Installation Steps

Step 1: Compile ModSecurity native library

Install required packages for compilation. For example, on Debian/Ubuntu like systems:

sudo apt-get install g++ make automake autoconf libtool

Install required dependent packages:

sudo apt-get install libxml2 libxml2-dev libxml2-utils libaprutil1 libaprutil1-dev apache2-prefork-dev

The native libraries (.so, .dll, etc.) needed for ModSecurity for Java are:

  1. zlib1 (Windows only)
  2. libxml2
  3. pcre
  4. libapr-1
  5. libapriconv-1 (Windows only)
  6. libaprutil-1
  7. ModSecurityJNI (JNI wrapper for mod_security code)

These native libraries are used by the ModSecurityFilter.

Download mod_security source code from GitHub, compile and install:

git clone https://github.com/mihaipitu/ModSecurity.git
cd ModSecurity/
./configure --enable-standalone-module --enable-java-module

Copy compiled library in a convenient folder:

sudo cp ./java/.libs/libModSecurityJNI.so /usr/lib/

The libModSecurityJNI.so file is the connector that plugs the "standalone" ModSecurity code into the Java application as a Filter.

Step 2: Add ModSecurity Java/Class Files to the App

To use the ModSecurity filter in your Java web application, you will need to copy either the source .java files or the compiled .class files into your application.

Scenario 1: Add ModSecurity source java files to application and create WAR

If you would like to add ModSecurity into your application and create a WAR file, then you should copy the source files from the ModSecurity/java/ModSecurityTestApp/src/java/org directory into your app directory structure and then create the WAF file:

# pwd
# ls -R
apache modsecurity



DefaultFileItemFactory.java DiskFileUpload.java FileUploadBase.java MultipartStream.java
DefaultFileItem.java FileItemFactory.java FileUploadException.java package.html
DeferredFileOutputStream.java FileItem.java FileUpload.java ThresholdingOutputStream.java

ModSecurityFilter.java MsHttpServletRequest.java MsHttpServletResponse.java MsOutputStream.java
ModSecurity.java MSHttpServletRequestWrapper.java MsHttpTransaction.java MsWriter.java
[root@localhost org]#

Scenario 2: Add ModSecurity compiled class files to an already compiled app

If you already have a compiled app and you would like to add in ModSecurity filtering without recompiling a new WAF file, you can instead use the compiled .class files. Simple unpack the ModSecurityTestApp.war file and copy the files into the running app's directory structure.

# jar xvf ModSecurityTestApp.war
created: META-INF/
created: WEB-INF/
created: WEB-INF/classes/
created: WEB-INF/classes/org/
created: WEB-INF/classes/org/apache/
created: WEB-INF/classes/org/apache/commons/
created: WEB-INF/classes/org/apache/commons/fileupload/
created: WEB-INF/classes/org/modsecurity/
extracted: META-INF/context.xml
extracted: WEB-INF/classes/org/apache/commons/fileupload/DefaultFileItem.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/DefaultFileItemFactory.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/DeferredFileOutputStream.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/DiskFileUpload.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileItem.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileItemFactory.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileUpload.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileUploadBase$InvalidContentTypeException.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileUploadBase$SizeLimitExceededException.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileUploadBase$UnknownSizeException.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileUploadBase.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/FileUploadException.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/MultipartStream$IllegalBoundaryException.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/MultipartStream$MalformedStreamException.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/MultipartStream.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/ThresholdingOutputStream.class
extracted: WEB-INF/classes/org/apache/commons/fileupload/package.html
extracted: WEB-INF/classes/org/modsecurity/ModSecurity.class
extracted: WEB-INF/classes/org/modsecurity/ModSecurityFilter.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletRequest$1.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletRequest$BodyDiskServletInputStream.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletRequest$BodyMemoryServletInputStream.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletRequest$InterceptServletInputStream.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletRequest$Parameter.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletRequest.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpServletResponse.class
extracted: WEB-INF/classes/org/modsecurity/MsHttpTransaction.class
extracted: WEB-INF/classes/org/modsecurity/MsOutputStream.class
extracted: WEB-INF/classes/org/modsecurity/MsWriter.class
extracted: WEB-INF/web.xml
extracted: help.html
extracted: index.jsp
# cp -R /tmp/ModSecurity/java/ModSecurityTestApp/dist/WEB-INF/classes/org/* /opt/apache-tomcat-7.0.42/webapps/WebGoat/WEB-INF/classes/org

Step 3: Activate the ModSecurityFilter in web.xml

The next step add the following entry for the filter tag in your web.xml file:

                <!-- Path to the main configuration file of ModSecurity. You can activate the core 
                     rules by including in modsecurity.conf file:
                        Include modsecurity_crs_10_setup.conf
                        Include activated_rules\*.conf
OPTIONAL parameters for loading native libraries from absolute paths. This is an alternitive to specifying
-Djava.library.path=/path/to/libs/ variable to the JVM which

zlib1 and libapriconv-1 are Windows only libraries
--> <init-param>
</init-param> </filter> <filter-mapping> <filter-name>ModSecurityFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

Step 4: Configure ModSecurity Settings

In the web.xml file, you added a path to the main modsecurity.conf file holding directives such as SecRuleEngine, SecAuditEngine, etc... You should update this file as needed for your environment.

# head /root/modsecurity-apache_2.7.2/modsecurity.conf
# -- Rule engine initialization ----------------------------------------------

# Enable ModSecurity, attaching it to every transaction. Use detection
# only to start with, because that minimises the chances of post-installation
# disruption.
SecRuleEngine DetectionOnly

Step 5: Add in Rule Files

The ModSecurity filter knows how to handle "Apache Include" directives in the "conf" param value. This means that if you want to create your own rule files or utilize the OWASP ModSecurity CRS, you should add appropriate Include directives to the main modsecurity.conf file:

# tail /root/modsecurity-apache_2.7.2/modsecurity.conf
# Specify your Unicode Code Point.
# This mapping is used by the t:urlDecodeUni transformation function
# to properly map encoded data to your language. Properly setting
# these directives helps to reduce false positives and negatives.
#SecUnicodeCodePage 20127
#SecUnicodeMapFile unicode.mapping

Include /root/owasp-modsecurity-crs/modsecurity_crs_10_setup.conf
Include /root/owasp-modsecurity-crs/base_rules/*.conf

Step 6: Start Java Server and Confirm ModSecurity Initialization

# /opt/apache-tomcat-7.0.42/bin/startup.sh
Using CATALINA_BASE: /opt/apache-tomcat-7.0.42
Using CATALINA_HOME: /opt/apache-tomcat-7.0.42
Using CATALINA_TMPDIR: /opt/apache-tomcat-7.0.42/temp
Using JRE_HOME: /usr/lib/jvm/java-1.6.0-openjdk
Using CLASSPATH: /opt/apache-tomcat-7.0.42/bin/bootstrap.jar:/opt/apache-tomcat-7.0.42/bin/tomcat-juli.jar # cat /opt/apache-tomcat-7.0.42/logs/localhost*.log Sep 27, 2013 6:35:18 PM org.apache.catalina.core.ApplicationContext log INFO: ModSecurity for Java (STABLE)/2.7.5 (http://www.modsecurity.org/) configured. Sep 27, 2013 6:35:18 PM org.apache.catalina.core.ApplicationContext log INFO: ModSecurity: APR compiled version="1.3.9"; loaded version="1.3.9" Sep 27, 2013 6:35:18 PM org.apache.catalina.core.ApplicationContext log INFO: ModSecurity: PCRE compiled version="7.8 "; loaded version="7.8 2008-09-05" Sep 27, 2013 6:35:18 PM org.apache.catalina.core.ApplicationContext log INFO: ModSecurity: LUA compiled version="Lua 5.1" Sep 27, 2013 6:35:18 PM org.apache.catalina.core.ApplicationContext log INFO: ModSecurity: LIBXML compiled version="2.7.6" Sep 27, 2013 6:35:18 PM org.apache.catalina.core.ApplicationContext log INFO: ModSecurity started.

Step 7: Test Rules

The next step is to send some example attacks to your application to ensure that the it is working properly. If you send some XSS attacks for instance, you should see logs similar to the following in the Tomcat logs directory:

Screen Shot 2013-09-27 at 1.52.09 PM

Step 8: Verify Audit Logging

In addition to the short, 1-line alert messages sent to the Tomcat logs, ModSecurity will also generate appropriate Audit log entries depending on your configuration. You can review the corresponding Audit log entry for your test request(s) to see fully request/response payloads:

Screen Shot 2013-09-27 at 1.55.52 PM


Screen Shot 2013-09-27 at 1.58.51 PM

Bonus Testing: BeanShell scripting with ModSecurity

You can use BeanShell scripts in SecRule ModSecurity directives using the exec action. First you need to put the bsh.jar file (which can be downloaded from beanshell.org) into the current directory of your server (for example $CATALINA_HOME/bin in Tomcat). An example of an exec can be the following:

# Alert and Block based on Anomaly Scores
SecRule TX:ANOMALY_SCORE "@gt 0" \
    "chain,phase:2,id:'981176',t:none,deny,log,msg:'Inbound Anomaly Score Exceeded (Total Score: %{TX.ANOMALY_SCORE}, SQLi=%{TX.SQL_INJECTION_SCORE}, XSS=%{TX.XSS_SCORE}): Last Matched Message: %{tx.msg}',logdata:'Last Matched Data: %{matched_var}',setvar:tx.inbound_tx_msg=%{tx.msg},setvar:tx.inbound_anomaly_score=%{tx.anomaly_score}"
        SecRule TX:ANOMALY_SCORE "@ge %{tx.inbound_anomaly_score_level}" chain
                SecRule TX:ANOMALY_SCORE_BLOCKING "@streq on" chain
                        SecRule TX:/^\d+\-/ "(.*)" "setenv:block_session=1,exec:/usr/local/apache/conf/beanshell_script.bsh"

The environment variable set in the SecRule can be accessed in BeanShell scripts using some pseudo-code like this to instruct the app to block the current session:

import org.owasp.webgoat.session.WebSession;
if (block_session != null) {
  session.setAttribute(BLOCKED, "true");


We encourage Java application server users to test out the new ModSecurity version and to give us feedback on any issues found. If you find any bugs, please contact through one of the following: