Back Orifice 2000 (BO2K) debuted in 1999 by US hacker group Cult of the Dead Cow. It was the successor to their Back Orifice remote administration tool, released the previous year.
Whereas the original Back Orifice was limited to the Windows 95 and Windows 98 operating systems, BO2K also supported Windows NT. In addition, BO2K was released open source.
