This chapter aims to increase the understanding on the sources of
cybersecurity threats in cryptocurrency. It reviews the extant
literature to identify the most common sources of cybersecurity threats
in cryptocurrency literature, more specifically those of 51 percent
attacks, sybil attacks, eclipse attacks and spam attacks. In addition to
reviewing the literature, the chapter provides illustrative examples of
the attacks and methods to prevent the attacks. It presents future
research avenues to improve cybersecurity in cryptocurrency. The threat
of 51% attack can be fixed with new hybrids that combine proof-of-work
with PoS. There can also be side-chain scaling that prevents 51%
attacks, or more voting power can be given to trustworthy nodes.
PoW-only coins can introduce new rules that restrict the size of large
mining pools to 5 percent of the entire hash rate. The chapter
highlights that too many cryptocurrency projects rely on trust and good
faith in lead developers and pools.