I interviewed Gnosis, they wouldn't go into any specific detail as to how they gained entry.
From what I have found out, it looks like they used a vulnerability found within a three year old Minify script that hadn't been upgraded. This gave them access to other parts of the server:
I just found it interesting that after reading plenty of "news sources" on the subject, I didn't get one authoritative post on HOW the hackers did it and WHY. The readme helped out but to hear directly from the hackers was quite informative. This post did. Then again, now that you bring it up, I'm not sure there's any way we can know if it's "authoritative" or not.
