Disclosure of h1 challenges name through the calendar
Discovered by rijalrojan on Security

This issue took 0 Days and 0 hours to triage and 0 Days and 4 hours to resolve once triaged.


It seems like the Calendar somehow grabs the name of the target for a h1 challenge even though the target name is not public.


h1challenges do not disclose the name of the target until the time it starts. For example for this challenge: █████ the name of the target is not disclosed anywhere and the page looks something like this:


However, once we import the calendar on something like Google calendar, it shows the name of the target:


This is super useful specially because sometimes program run multiple challenges in short period of time. For example, knowing more about this challenge (the name of the target), a hacker can hack and hodl bugs until the program starts.

Steps To Reproduce

  1. Add yourself to challenge like the one linked above.
  2. Link/update your Google Calendar with the hackerone events calendar.
  3. Find the date in the calendar when the challenge is set to start and you can see the name there.


Disclosure of h1c-* challenge targets.