Anyway I can give you the skinny of the situation:

1) Backtrack 2 did not have an installer, it was a live-CD. But that doesn't stop you installing it by just copying the live environment to a disk (with some mount-binding and grub install, you're all good!) There were guides for doing this although they all had large warnings and the backtrack maintainers cautioned heavily against doing it.

2) because it was a liveCD there was no package update mechanism, it was not based on debian at the time so there was no apt or anything similar, even if there was there was no repositories, backtrack was a "tool" not a distro really.

3) sshd is one of the services that gets started on system boot for backtrack2.

4) someone at defcon unveilled an sshd exploit, a pretty nasty one, they had disclosed responsibly and everyone had been patched for at least 6 months, except the people who went against recommendations and installed backtrack2. They all got rooted.

Bonus: everyone who ran backtrack2, without exception, ran it with the root user; as that was the default and they had patched software that normally complains about such things to not complain. xD