Usually, binary Sybil/non-Sybil classifiers have
high false positives; thus, manual inspection
needs to be involved in the decision process for
suspending an account. SybilRank [20] aims to
efficiently derive a Sybil-likelihood ranking; only
the most suspicious accounts need to be inspected
manually. It is based on efficiently computable
early-terminated RWs and is suitable for
parallel implementation on a framework such as
Map Reduce, uncovering Sybils in OSNs with
millions of accounts. SybilRank is deployed and
tested in the operation center of Tuenti, which is
the largest OSN in Spain with 11 million users.
Almost 100 and 90 percent of the 50K and 200K
accounts, which SybilRank regards as the most
suspicious, are indeed fake. In contrast, the hit
rate of the current user-report-based approach is
only 5 percent. Thus, SybilRank represents a significant
step toward practical Sybil defense.