Pentest: 0day in iTop 2.4.0 gave me Domain Admin privileges

This article describes exploitation of a 0day RCE in webapp iTop 2.4.0. After getting a shell, I inserted credential sniffer, and next day walked away with a password of domain administrator.

Further you will find a step-by-step writeup and a link to Metasploit module.

TL;DR:

• If you face iTop < 2.4.1 and log in with an unprivileged account, you can run my Metasploit module that will upload a shell for you.
• Vendor issued a patch and allowed me to publish the article.

iTop is a solution for IT Service Management. It allows administrators to manage user requests, incidents, and service catalog in a single web application. If you request a new SSD from IT Department, it will most likely appear as a ticket in iTop. When you will collect your hardware, system administrator will log into iTop and change status of SSD: “assigned to user httpsonly, desk 1337”.

Step 1: Log in by any means
During reconnaissance, I found a domain helpdesk.company.com:

 

According to Documentation, Administrator of iTop can create local users or configure domain authentication:



In my case, I already had credentials of a domain user. Nothings stops you from trying to bruteforce passwords of local users: test:test, 111:111, user1:user1, backup:backup and so on.



Cool! I am logged in as a low-level user.


Step 2: Exploit Indirect Object Reference

Low-level user can access any profile by specifying user id. Here we query user with id=1, which will likely have administrator rights. Server answers with a 302 redirect, but shows the content of the requested page.


Cool! We have the username: “admin”.


Step 3: Change password of administrator
According to Documentation, iTop provides a powerful CSV Import feature to assist end-users (and administrators) in massively creating or updating objects in iTop.

Our low-level user does not have right to create users. Error about insufficient rights appears.
There is no error of insufficient rights if we update a password of existing user. 0day! (take a look at the patch).

Let’s try to exploit it.
During update, iTop’s parsing system correlates all POST data (first name, last name, email, login, etc) with parameters in a database: non-empty database parameters must match POST parameters. Sad, but we do not know all attributes of user admin (e.g. group membership) and cannot specify them.

Trick: if you tell iTop to copy all parameters from a given profile, it will set all non-empty parameters from profile with a given id – think of this action as a pointer to object with property “profileid=1”.


Password changed! You can find full HTTP query in my metasploit module.


Step 4: Login as admin
After we have changed administrator’s password, we can log in using new password:
 
 


Step 5: RCE
Administrator can achieve RCE through ConfigEditor (functionality for editing iTop configuration file). You will be able to execute RCE and leave original configuration file unmodified.



After having RCE, I edited authentication script to record successful login attempts. The following string was added:

./application/loginwebpage.class.inc.php:


Few days later, I got domain admin’s password in log.txt.