The central vulnerabilities of LR, as with other mechanisms designed based on the assumption of unilateral optimization, are collusion and fraud. Collusion takes place when multiple agents act in their mutual interest to the detriment of other participants. Fraud takes place when a single citizen misrepresents herself as many.
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.