Blockchain systems become increasingly attractive targets for cybercrime due to the rising amount of value transacted in respective systems. However, researchers and practitioners alike lack a comprehensive overview of existing attacks and a directive discussion of resulting implications. Employing a structured literature review, we an-alyze academic research concerning malicious attacks on blockchain systems. We ex-tract 87 relevant attacks and structure those using the attack tree notation. Our re-sults show that the academic discourse revolves mainly around the analysis of a few individual attacks, and most publications deal with attacks on either Bitcoin or Ethereum. We further find that most attacks target the on-chain application logic component (smart contracts) of the blockchain technology stack as well as consensus mechanisms. A majority of attacks are mitigable, and socio-technical components play an important role in both attacks and applying effective countermeasures