How I Found My First Easy P3 Vulnerability in HackerOne Bug Bounty‍

I recently completed my first bug bounty, and I wanted to share the experience and key lessons I learned along the way. This journey has been eye-opening, not just from a technical perspective but also in understanding how valuable even seemingly minor vulnerabilities can be to an organization’s security posture.

While testing a web application for a vulnerability, I noticed that several email addresses associated with system administrators were visible. These were part of the admin accounts, which often have elevated privileges compared to normal users. Here’s why this is a problem:

Admin Emails: A Target for Attackers
Administrator email addresses are high-value targets for attackers. These email accounts usually belong to individuals who have greater control over systems and sensitive data. Exposing such information makes it easier for attackers to launch targeted phishing attacks or other forms of social engineering.Email Structure: Insight into the Organization’s Infrastructure
Beyond just email addresses, I noticed that the domain names used — such as example.com and domain.example.com—were visible, along with a server reference (xxxx03). This information, though seemingly harmless on its own, could provide attackers with clues about the underlying infrastructure of the organization. By understanding the server structure and domain naming conventions, an attacker can start mapping the internal network, which can lead to more sophisticated attacks down the line.

After identifying the vulnerability, I reported it to the organization through their bug bounty program. I was thrilled to receive the following response:

“Thank you for your submission! We were able to validate your report and have submitted it to the appropriate remediation team for review. They will let us know the final ruling on this report, and when/if a fix will be implemented. Please note that the status and severity are subject to change.”

This was a big moment for me! Knowing that my discovery was validated and that the report was escalated for remediation made all the effort worth it.

Even Small Leaks Matter: Initially, I wasn’t sure if exposed email addresses would be considered critical enough for a bug bounty, but it turns out that even these minor details can lead to larger vulnerabilities. Never underestimate the power of small leaks.Think Like an Attacker: When testing systems, always consider how an attacker might use the information at hand. What seems insignificant to a developer or system admin can be a valuable clue for someone looking to exploit the system.Persistence Pays Off: The bug bounty process can be slow, but persistence and patience are key. You may not always get an immediate response, but your findings can have a real impact on improving security.