Blockchain Security Training Network & Node Security 2

Question 1

An attacker isolates a node from the honest network and feeds it a false view of the blockchain. What attack is this?

Accepted Answer

Eclipse attack

Answer

Replay attack

Answer

Dusting attack

Answer

Sybil reorg

Question 2

Which practice best mitigates eclipse attacks on a node?

Accepted Answer

Diversifying inbound/outbound peers and using anchor connections

Answer

Increasing block size

Answer

Disabling the mempool

Answer

Lowering the gas limit

Question 3

What is the primary purpose of a node running behind a firewall exposing only the necessary P2P port?

Accepted Answer

Reduce the attack surface for remote exploitation

Answer

Increase block reward

Answer

Speed up consensus

Answer

Lower transaction fees

Question 4

A full node's RPC interface is exposed to the public internet without authentication. What is the main risk?

Accepted Answer

Unauthorized commands, wallet access, or DoS

Answer

Faster syncing

Answer

Higher staking yield

Answer

Improved peer discovery

Question 5

Which transport-layer protection helps secure communication between a node and its remote RPC clients?

Accepted Answer

TLS encryption with authentication

Answer

Plaintext HTTP

Answer

Disabling all logging

Answer

Removing the firewall

Question 6

What does a Sybil attack on a peer-to-peer blockchain network involve?

Accepted Answer

Creating many fake identities to gain disproportionate influence

Answer

Double-spending via a 51% hash share

Answer

Forging a single TLS certificate

Answer

Exploiting a smart contract reentrancy bug

Question 7

Why is keeping node software updated a critical network-security control?

Accepted Answer

Patches fix known vulnerabilities and consensus bugs

Answer

It increases the token price

Answer

It removes the need for a firewall

Answer

It disables peer discovery