FREE Blockchain Security Training Network and Node Security Questions and Answers

Question 1

An attacker manages to take control of a blockchain node's peer connections, ensuring all its incoming and outgoing traffic is routed through attacker-controlled nodes.
This effectively isolates the victim node from the honest network, allowing the attacker to feed it false information.
What is this type of network-level attack called?

Accepted Answer

An Eclipse Attack

Answer

A 51% Attack

Answer

A Sybil Attack

Answer

A Timejacking Attack

Question 2

Which of the following best describes the primary security benefit of maintaining client diversity on a blockchain network like Ethereum?

Accepted Answer

It prevents a single bug in one client implementation from causing a network-wide failure or fork.

Answer

It increases the total number of nodes, making the network more decentralized.

Answer

It allows for faster transaction processing through parallel client execution.

Answer

It reduces the storage requirements for individual nodes by sharding data.

Question 3

Which of the following actions constitutes a Distributed Denial-of-Service (DDoS) attack specifically targeted at the *application layer* of a blockchain network?

Accepted Answer

Repeatedly sending computationally inexpensive but valid transactions that consume significant node resources for validation.

Answer

Hijacking BGP routes to redirect traffic between major validator nodes.

Answer

Flooding a node's IP address with a high volume of TCP SYN packets.

Answer

Gaining control of over 51% of the network's staking power.

Question 4

A node operator for a Proof-of-Stake network exposes the node's JSON-RPC endpoint to the public internet without proper authentication. The operator later discovers that the validator keys stored on the node have been used to sign a malicious message, leading to a slashing penalty. What is the MOST likely cause of this security breach?

Accepted Answer

The RPC endpoint exposed sensitive methods, allowing the attacker to remotely use the node's private keys.

Answer

A zero-day exploit in the node's client software.

Answer

The attacker performed a successful 51% attack on the network.

Answer

The node's system clock was manipulated in a Timejacking attack.

Question 5

What is the primary goal of a Timejacking attack against a blockchain node?

Accepted Answer

To manipulate the node's perception of network time, potentially causing it to accept invalid blocks or reject valid ones.

Answer

To steal cryptocurrency directly from the node's wallet.

Answer

To isolate the node from its peers by manipulating its peer list.

Answer

To install malware on the node's host machine for long-term surveillance.

Question 6

During the peer discovery process, a new blockchain node must find and connect to honest peers to synchronize with the network. Which of the following represents a significant security risk during this initial phase?

Accepted Answer

The node connecting exclusively to hardcoded, but malicious, bootstrap nodes.

Answer

The node's firewall blocking all outgoing P2P traffic.

Answer

The node using Elliptic Curve Cryptography (ECC) instead of RSA for key pairs.

Answer

The node downloading the entire blockchain history from a single, slow peer.