Figure 1.9: Sybil Attack

Such manipulations can result in a 51% attack in the Bitcoin or

similar networks running with a PoW consensus. Such attacks can

be prohibited in a permissioned Blockchain after a background

verification of each participant.

1.7.3 DDoS Attack

Figure 1.10 illustrates the DDoS or a distributed denial of service,

which is a cyber-attack where the hacker uses bots to send a huge

number of requests to the specific server and totally consume all of

its resources, as shown as follows: