Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing, maintained and funded by Offensive Security Ltd. Hacker has stated that the hacked subdomain is being hosted by a company called Mailman List and that, Mailman List is vulnerable to #heartbleed vulnerability which he used to gain access to the administrative account. Kali Linux team later tweeted that hacked subdomain was infact inactive. It was also a 3rd party domain with 0 volume mailing list and hence they were least worried about the hacking.
