The first half of November 2012 has been undoubtedly characterized by Hacktivism. Not only the month has begun with the ProjectBlackStar by the infamous Team Ghostshell (2.5 million accounts leaked belonging to different Russian sectors), but also the long-awaited November 5 has brought an unprecedented wave of Cyber Attacks against organizations all over the world, including Symantec and the UK Ministry Of Defence (more than 3,000 accounts leaked in both cases).
Update June 4 2012: May 2012 Cyber Attacks Timeline (Part II)
As usual here it is the timeline of the Main Cyber Attacks occurred in May (at least according to my evaluation criteria).
This first half of the month has seen the arrival of a new hacking collective, “The Unknowns”, who has performed an impressive trail of attacks during the first days of May, targeting Space Agencies, Universities, and several other organizations. Although these events appear to be closer to cyber crime actions rather than hactivistim-driven attacks, they have not been the most remarkable ones of these days: as a matter of fact chronicles report of a massive breach at the Hangzhou Dianzi University, targeting approximately 150.000 acccounts.