On February 6 2017, a bug bounty hunter called madrobot published a report about domain takeover in Ubiquiti.
madrobot discovered that one of Ubiquiti's subdomains was pointing to the following Google IP address:
216.58.203.243 moderator.ubnt.com 216.58.203.243 ghs.google.com 216.58.203.243 ghs.l.google.com
The DNS register for the sub-domain was illustrated in the follow-up evidence, as shown in the following screenshot:
So, when the user entered the sub-domain moderator.ubnt.com from the web browser, it showed Google's page instead, as shown in the following screenshot:
As we can see, any user can claim the sub-domain for themselves and use it to damage Ubiquiti.
If you want to read more about this bug, visit the following link: https://hackerone.com/reports/181665.