Enhancing Boofuzz Process Monitoring for Closed-Source SCADA System Fuzzing

Abstract

Past cyber-attacks have demonstrated that Industrial Control and SCADA Systems are high-value targets for modern threat actors. In order to defend these classes of systems, it is necessary to detect and eliminate any pre-existing vulnerabilities before they can be leveraged into zero-day exploits. Different methods exist to find exploitable vulnerabilities in the software that runs these systems, one of which is known as fuzzing – wherein a system under test is exposed to a variety of input streams while simultaneously observed for unexpected behaviours, exceptions, or crashes. The aim of this research is to extend the Boofuzz network protocol-based fuzzing framework in order to effectively monitor a closed-source SCADA HMI endpoint during fuzz testing. Effective monitoring in this context is defined as the automated detection of target crashes during fuzzing which are recorded with an exception description, reproducing steps, and call stack trace. This data minimizes the time required for vulnerabilities discovered during fuzzing to be reproduced, investigated, and rectified by the software vendor. In order to accomplish this aim, our SCADA HMI is first analyzed to identify the fuzzing target and its runtime behaviours. A protocol fuzzer is then custom built for it using Boofuzz, with the existing target process monitor class extended to introduce new log file and debugger-based monitors. These extensions are then tested through fuzz tests of the SCADA HMI, the results from which demonstrate that vulnerabilities can be both automatically detected and recorded with the sufficient level of detail to expedite rectification.