Sybil attack
An impersonation attack is a form of security threat on an online system, when someone tries to take control of the network by creating multiple accounts, nodes or computers.
This type of attack can be as simple as someone creating a series of social media accounts.
But in the world of cryptocurrency, a more accurate example is when someone operates multiple nodes on a blockchain network.
The “Sybil” in the name of this type of attack comes from the case of a woman named Sybil Dorsett, who was treated for Dissociative Identity Disorder - also known as Multiple Personality Disorder.
What problems can impersonation attacks cause?
Attackers can win more votes than real nodes on the network if they create enough fake identities (or Sybil identities). They can then refuse to receive or send blocks and succeed in blocking other users from the network.
In very large-scale impersonation attacks, when the attacker controls the majority of the network's computing power or hash rate, they can perform a 51% attack. In such cases, they may change the orders of transactions, and prevent transactions from being confirmed. They can even reverse transactions they made while in control, which can lead to double consumption.
Over the years, computer scientists have spent a lot of time and research trying to find ways to detect and prevent impersonation attacks with varying degrees of success. Currently, there is no guaranteed defense against these attacks.
So how can blockchain mitigate Sybil attacks?
Many blockchains use different “consensus algorithms” to help defend against impersonation attacks such as Proof of Work, Proof of Stake, and Delegated Proof of Stake.
These consensus algorithms don't actually prevent impersonation attacks, they just make it impractical for an attacker to successfully perform an impersonation attack.
For example, Bitcoin's blockchain applies a specific set of rules towards the creation of new blocks.
One of the principles is that the ability to create new blocks must be proportional to the total processing power of the Proof of Work mechanism. That means you have to actually possess the computing power needed to create a new block, which is very difficult and expensive for an attacker.
Because Bitcoin mining is highly profitable, miners have a strong incentive to mine honestly, rather than attempting impersonation attacks.
In addition to impersonation attacks, there are several other common types of attacks. Read more articles on Binance Academy!