Last updated at Wed, 03 Jan 2024 21:05:00 GMT

At Rapid7 we love a good pen test story. So often they show the cleverness, skill, resilience, and dedication to our customer’s security that can only come from actively trying to break it! In this series, we’re going to share some of our favorite tales from the pen test desk and hopefully highlight some ways you can improve your own organization’s security.

Rapid7 was tasked with testing a provider website in the healthcare industry. Providers had the ability on the website to apply for jobs, manage time cards, connect with employers needing help at hospitals, apply for contracts, as well as manage certificates and documents that were needed to perform duties. The provider website was interested to see if their web application had any flaws that could be leveraged as an attacker, as the application was heavily customized.

I began by testing input fields for any vulnerabilities. If an input field does not sanitize user input correctly this could open the web application for potential attacks that allow an attacker to inject code. The vulnerable form with injected code could then be used to attack the web application or target users. An input field can be anything that allows you to enter information into the web application, like your name or email address. I discovered a field that was not correctly sanitizing input and when submitted, was viewed by accounts with administrative access.

Using the leverage gained from the vulnerable field I was able to perform a Cross Site Scripting (XSS) attack which stores JavaScript in a vulnerable form and returns the JavaScript to users. When a user views a vulnerable form with injected code, the code is executed inside the victim's browser. An XSS payload was created that, when viewed by users, sent a refresh token to a server under our control. This allowed us to collect administrative tokens for accounts that viewed the vulnerable form, resulting in account takeovers. I also discovered that the refresh token was misconfigured and allowed indefinite access to the web application once obtained. With said refresh token in hand I could log in to the account indefinitely even if the password was changed.

I then turned my attention to authorization issues on the web application. As a non-privileged user, I discovered a dashboard that allowed providers to view expiring documents. The request was vulnerable to Broken Object-Level Authorization and Insecure Direct Object Reference (IDOR). so I was able to manipulate the request to access streams of all uploaded documents for all end users with accounts on the web applications. These documents included all healthcare documents uploaded to the application including background checks, Social Security information, addresses, physician documents, and more.

Further analysis of the application showed that unprivileged users could access calls that were being utilized by administrative users. These calls disclosed sensitive information including usernames and passwords for vendors and staff associated with contracted hospitals on the application. As a non-privileged user account, I utilized this authorization issue in combination with an IDOR vulnerability to scrape usernames and passwords from the vulnerable endpoint for over 15,000 accounts in minutes.

Chasing a hunch that there would be more misconfigurations to exploit, I discovered that candidates for hospital positions at multiple locations had cleartext Social Security numbers stored in an administrative portion of the web application. An API endpoint was used to retrieve the information, and the endpoint was vulnerable to IDOR. I performed a brute force attack to retrieve names and cleartext Social Security numbers from hundreds of accounts being stored in the application.

This test highlighted some issues present in a large amount of web applications. We demonstrated just how quickly adversaries could exfiltrate sensitive data from an application that did not have safeguards in place. We also demonstrated just how important ensuring user input is sanitized correctly in an application and how failing to do so correctly can put users and the company at risk. Ensuring users are isolated and authorization is implemented appropriately is another major factor to consider when operating in the healthcare industry, as protecting client data is critical when dealing with protected health information and personally identifiable information.

The client was shocked at the results of testing the security of the application. The test disclosed some serious vulnerabilities that were not previously discovered by past testing from other security vendors, highlighting the importance of continuous testing especially for a customized application that was constantly evolving.