Measuring and Defeating Anti-Instrumentation-Equipped Malware

Malware authors constantly develop new techniques in order to evade analysis systems. Previous works addressed attempts to evade analysis by means of anti-sandboxing and anti-virtualization techniques, for example proposing to run samples on bare-metal. However, state-ofthe-art bare-metal tools fail to provide richness and completeness in the results of the analysis. In this context, Dynamic Binary Instrumentation (DBI) tools have become popular in the analysis of new malware samples because of the deep control they guarantee over the instrumented binary. As a consequence, malware authors developed new techniques, called antiinstrumentation, aimed at detecting if a sample is being instrumented. We propose a practical approach to make DBI frameworks more stealthy and resilient against anti-instrumentation attacks. We studied the common techniques used by malware to detect the presence of a DBI tool, and we proposed a set of countermeasures to address them. We implemented our approach in Arancino, on top of the Intel Pin framework. Armed with it, we perform the first large-scale measurement of the anti-instrumentation techniques employed by modern malware. Finally, we leveraged our tool to implement a generic unpacker, showing some case studies of the antiinstrumentation techniques used by known packers.