Have you ever heard of the phrase “Sybil Attack”? May the process of making multiple accounts threaten your security? What do you think!?

To be historically analyzed, the phrase “Sybil Attack” comes from a case study about a woman named Sybil Dorsett who had an Identity Disorder called Multiple Personality.
In the world of cryptocurrency, a relevant example is where somebody runs multiple nodes on a blockchain network. 

But how can it lead to bad impacts on account security?

1)Attackers may be able to out-voting the honest nodes on the network if they create enough fake identities which are the Sybil Identities. Thus, then they can refuse to receive or transmit blocks, effectively blocking other users from a network.

2)In a large scale of Sybil Attack where the attackers manage to control the majority of the network computing power, they can carry out a 51% attack. In such cases, they may change the transaction order, and prevent it from being confirmed. They may even reverse transactions that they made while in control, which causes double-spending!

So how can an account be protected from Sybil Attacks?

Many blockchains use different consensus algorithms to defend against Sybil Attacks. Proof of Work and Proof of Stake are two of them.
Although these consensus algorithms can’t utterly prevent Sybil Attacks, they just make it very incapable of being successfully carried out by the attackers.

As a result, if you are somehow involved with the cryptocurrency world, better consider the danger of attackers and watch it out!