FirstBlood-#164Can know who are attending an HackerBack event
This issue was discovered on FirstBlood v1.0.0



On 2021-05-11, codersanjay Level 3 reported:

The following endpoint is present in source code.

It seems like it will show status of attendees who are attending an event.

But after sending POST/GET request to this end point, it was throwing 200OK but no content.

I then realised, may be a header should be added which I saw in the source code drpanel.

Sent a modified request.

It was leaking info of who are attending the event.

I also see the ID of old event.Tried sending same request with old event id.

Impact

PII info leak.

P1 CRITICAL

Endpoint: /attendees/event.php?q=560720

Parameter: x-site-req

Payload: nil


FirstBlood ID: 13
Vulnerability Type: Information leak/disclosure

/attendees/event can be seen on the HackerBack.html page but has a blank response. Upon further inspection and from making use of the web app, you will notice you can add certain headers in order to interact with this endpoint. An old event ID leaks PII information about attendees.