Formal Modeling and Verification of Security Properties of a Ransomware-Resistant SSD

Solid-state drives (SSDs) are fast emerging as the primary choice for data storage in diverse domains. However, data protection against ransomware attacks on such storage devices is a crucial challenge. A recent research work proposed an In-SSD ransomware protection mechanism to improve SSD data security. The SSD flash translation layer (FTL), which consists of an address mapping, garbage collection, and wear leveling components, is inherently the most complex part of an SSD controller. The In-SSD ransomware protection mechanism adds a new component to the FTL, making the FTL design more complex. The new component interacts with almost all other units of FTL for recovery from a ransomware attack. Such a design would naturally require rigorous verification, which is the focus of this article. In this work, we discuss the derivation of a set of security properties related to protection from ransomware that covers the security requirements and the design; we next prove such properties using symbolic model checking.