Distributed protocols are the foundation for the modern internet, and therefore ensuring their correctness and security is paramount. To this end, formal methods, the use of mathematically rigorous techniques for reasoning about software, has been increasingly employed to analyze and study distributed protocols. Historically, formal methods has been employed for reasoning about concurrency and the correctness of distributed systems, and in recent years formal methods has been employed to reason about the security of cryptographic protocols and primitives. However, no previous formal methods tools offered an effective solution for studying denial of service attacks on protocols.

To fill this gap we introduce \korg, a tool for synthesizing attacks on distributed protocols that implements the theoretical framework proposed in Hippel et al. In particular, \korg targets the communication channels between the protocol endpoints, and synthesizes attacks to violate arbitrary linear temporal logic (LTL) specifications. \korg either synthesizes attack, or proves the absence of such via an exhaustive state-space search. \korg is sound and complete, meaning if there exists an attack \korg will find it, and \korg will never have false positives. \korg supports pre-defined attacker models, including attackers that can replay, rearrange, or drop messages on channels, as well as custom user-defined attacker models. Although \korg best lends itself for reasoning about denial of service attacks, it can target any specification expressable in LTL. We present a variety of case studies illustrating the employability and usefulness of \korg.
