An eclipse attack is a network-level attack in which an attacker attempts to surround a particular blockchain node with attacker-controlled connections. The victim may then stop receiving reliable information from the rest of the network.

A blockchain node depends on network connections to receive blocks, transactions, and other information. If most or all of its available connections are controlled by an attacker, the node may receive a manipulated view of the network state.

Eclipse attacks are particularly dangerous as an enabling mechanism. Isolating a node does not by itself provide complete control over the blockchain, but it can make other attacks easier. An attacker may hide specific transactions or blocks from the victim or create conditions that cause the node to make incorrect decisions.

Protection

  • maintaining a large and diverse peer set;
  • avoiding excessive dependence on a single source of peer addresses;
  • randomizing and periodically changing connections;
  • checking important information through independent peers.

An eclipse attack demonstrates that blockchain security depends on more than cryptography and consensus. Reliable network infrastructure is also part of the overall security model.