As more and more systems are controlled by computers and connected to the Internet, a tremendous amount of activity is generated when these systems interact with each other and with their users. The continuous stream of data related to such Internet-connected and computer-controlled systems is known as Big Data and introduces problems at new scales. Computer security and privacy can both benefit and suffer from Big Data, as tools and techniques are made readily available to process security-event streams and as attacks are harder to detect in the huge volume of event data. The BADGERS'12 workshop is a forum for discussing the challenges in and potential solutions for taking advantage of Big Data for improving computer security and privacy. The workshop builds on the successful first edition of BADGERS which was held in conjunction with the EuroSys 2011 conference in Salzburg, Austria .