Hacker Earns $8,500 for Vulnerability in HackerOne Platform

A white hat hacker has earned $8,500 for a serious vulnerability that exposed the email addresses of HackerOne users.

Earlier this month, a hacker who uses the online moniker msdian7 discovered that a new feature introduced by the HackerOne bug bounty platform had resulted in a vulnerability that could have been exploited to obtain any HackerOne user’s email address.

The feature was introduced on February 10 and msdian7 found the vulnerability the next day. The vulnerability was patched within a few hours by HackerOne, and by the end of the day the company had sent out notifications to two individuals whose email addresses were exposed during the tests conducted by msdian7.

The security hole, described by HackerOne as an improper authorization issue, was related to the platform’s invitation system, which allows bug bounty program administrators to send out invitations to users. These invitations can be sent out to invite someone to a private program, to claim bounties, or be added to a program.

Invitations can be sent out to a username or an email address, but if a user is invited based on their username, the sender is not given access to that user’s email address for privacy purposes. This rule was enforced with access control lists (ACLs), but when HackerOne introduced a new protection layer the ACL rule was not properly implemented, thus exposing user email addresses.

The vulnerability could have been exploited for malicious purposes through HackerOne’s demo programs.

“HackerOne provides demo programs for customers to experience the product as well as hackers to test against our production system. When you are a team member in a demo program, you can demo the report interface. In the report interface, you can invite an external participant to the report, which could be any user on the platform. By generating that invitation with a username and then viewing the invitation, the user’s email could have been exposed,” HackerOne explained.

HackerOne awarded a $7,500 bounty for this vulnerability, along with a $1,000 bonus because the flaw was discovered less than 24 hours after the problematic feature was introduced. Details of the vulnerability were disclosed by HackerOne last week.

This is not the first time HackerOne has awarded a significant bounty for a vulnerability found in its platform. Last year, the company awarded a $20,000 bounty after a white hat hacker demonstrated that he could access private vulnerability reports.

Related: HackerOne Surpasses $82 Million in Paid Bounties

Related: Researcher Gets $5,000 for Severe Vulnerability in HackerOne