Biblio

Finding identical digital objects (or artifacts) during a forensic analysis is commonly achieved by means of cryptographic hashing functions, such as MD5, SHA1, or SHA-256, to name a few. However, these functions suffer from the avalanche effect property, which guarantees that if an input is changed slightly the output changes significantly. Hence, these functions are unsuitable for typical digital forensics scenarios where a forensics memory image from a likely compromised machine shall be analyzed. This memory image file contains a snapshot of processes (instances of executable files) which were up on execution when the dumping process was done. However, processes are relocated at memory and contain dynamic data that depend on the current execution and environmental conditions. Therefore, the comparison of cryptographic hash values of different processes from the same executable file will be negative. Bytewise approximation matching algorithms may help in these scenarios, since they provide a similarity measurement in the range [0,1] between similar inputs instead of a yes/no answer (in the range 0,1). In this paper, we introduce ProcessFuzzyHash, a Volatility plugin that enables us to compute approximation hash values of processes contained in a Windows memory dump.

During the last years, criminals have become aware of how digital evidences that lead them to courts and jail are collected and analyzed. Hence, they have started to develop antiforensic techniques to evade, hamper, or nullify their evidences. Nowadays, these techniques are broadly used by criminals, causing the forensic analysis to be in a state of decay. To defeat against these techniques, forensic analyst need to first identify them, and then to mitigate somehow their effects. In this paper, wereview the anti-forensic techniques and propose a new taxonomy that relates them to the initial phase of a forensic process mainly affected by each technique. Furthermore, we introduce mitigation techniques for these anti-forensic techniques, considering the chance to overcome the anti-forensic techniques and the difficulty to apply them.