A Methodology for Retrieving Information from Malware Encrypted Output Files: Brazilian Case Studies

This article presents and explains a methodology based on cryptanalytic and reverse engineering techniques that can be employed to quickly recover information from encrypted files generated by malware. The objective of the methodology is to minimize the effort with static and dynamic analysis, by using cryptanalysis and related knowledge as much as possible. In order to illustrate how it works, we present three case studies, taken from a big Brazilian company that was victimized by directed attacks focused on stealing information from a special purpose hardware they use in their environment.