  Audit logs serve as a critical component in enterprise business systems and
are used for auditing, storing, and tracking changes made to the data. However,
audit logs are vulnerable to a series of attacks enabling adversaries to tamper
data and corresponding audit logs without getting detected. Among them, two
well-known attacks are "the physical access attack," which exploits root
privileges, and "the remote vulnerability attack," which compromises known
vulnerabilities in database systems. In this paper, we present BlockAudit: a
scalable and tamper-proof system that leverages the design properties of audit
logs and security guarantees of blockchain to enable secure and trustworthy
audit logs. Towards that, we construct the design schema of BlockAudit and
outline its functional and operational procedures. We implement our design on a
custom-built Practical Byzantine Fault Tolerance (PBFT) blockchain system and
evaluate the performance in terms of latency, network size, payload size, and
transaction rate. Our results show that conventional audit logs can seamlessly
transition into BlockAudit to achieve higher security and defend against the
known attacks on audit logs.
