Sybil Attack

We define a Sybil attack per

In a Sybil attack, the attacker subverts the reputation system of a network service by creating a large number of pseudonymous identities and uses them to gain a disproportionately large influence. It is named after the subject of the book Sybil, a case study of a woman diagnosed with a dissociative identity disorder.

https://en.wikipedia.org/wiki/Sybil:attacken.wikipedia.org