[Explained] Overview for Sybil Attack | Example and Prevention

What Is a Sybil Attack?

What is a Sybil attack?

Sybil attack refers to an attack mode that uses a few nodes in a social network to control multiple false identities, so as to use these identities to control or influence a large number of normal nodes in the network.

The Sybil attack can create multiple identities to break down a reputation system where users are allowed to rate each other in online communities in order to build trust through reputation, so that the attackers can gain the majority of influence in the network to carry out illegal actions in the system.

Sybil attacks first appeared in the wireless communication field and then presented in the context of peer-to-peer networks, it can be used to destroy redundant mechanisms in distributed storage systems. At the same time, there are also threats to the routing mechanism in sensor networks.

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Examples of Sybil Attack

The Sybil attack is a massive destructive attack against the sensor network where numerous genuine identities with forged identities are used for getting an illegal entry into a network.

Apart from the sensor network, we will give you an example to clarify the Sybil attack in blockchain.

The Bitcoin network is a peer-to-peer network of nodes, implementing the Bitcoin protocol. When you get in there, you need to respect the protocol and operation decisions are made by votes, which means with more voting rights, the power is greater.

Sybil attack can take advantage of this point to create multiple fake identities by gathering information from nodes and then they can vote for as many identities as they control. Once the process succeeds, the attacker can block other users from legitimately using the network with a censorship.

Besides, the Tor network also allows peer-to-peer models and anonymously Internet surfing but that make chances for attackers to take control of thousands of nodes, threatening the privacy of the network.

Types of Sybil Attack

There are several types for Sybil attack.

1. Direct communication. In this method, the Sybil node can directly communicate with legitimate node. When a legitimate node sends a wireless message to a Sybil node, one of the Sybil nodes listens for the message.

2. Indirect communication. In this method, no legitimate node can communicate with Sybil node directly. Instead, one or more malicious nodes claim they can reach Sybil nodes.

Therefore, messages sent to Sybil nodes are routed through one of the malicious nodes, which pretends to send the message to Sybil node, when in fact the malicious node itself receives or intercepts the message.

3. Simultaneous attack. This method means that attackers involved all of his Sybil identities in one network communication at a time. If a node can only use its identity once, then the malicious node can iterate through its multiple Sybil identities to make it look like multiple nodes.

4. Non-simultaneous attack. In this method, an attacker can use only a portion of the Sybil identity in a specific time period, and then disappears and re-appears as another Sybil identity in another time period, which will make the whole process look like normal node revocation and joining in the network.

5. Identity theft. In this method, an attacker cannot forge identities when with a mechanism to identify nodes. Therefore, the attacker needs to assign a legitimate identity to the Sybil node. And it is hard to detect the falsity because the original nodes have been destroyed or invalidated.

How to Prevent Sybil Attack?

According to what Douceur promoted, a scheme of using trusted certificate center to verify the identity of communication entity is proposed to prevent Sybil attack.

The harm of Sybil attack has been analyzed, including routing, resource allocation and illegal behavior detection. Besides, by classifying Sybil attack scientifically, the attack can be detected by wireless resource detection.

In addition, identity registration and random key distribution schemes are used to establish secure connections between nodes to prevent Sybil attacks.

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Bottom Line:

This article has given you a detailed introduction to a Sybil attack and tell you the way to prevent it. Hope this post has resolved your concerns.