CBSE Node and Network Security 2

Question 1

Which attack vector allows a malicious node to return false transaction data to lightweight blockchain clients that rely on SPV (Simplified Payment Verification)?

Accepted Answer

Eclipse attack

Answer

Sybil attack

Answer

Finney attack

Answer

Vector76 attack

Question 2

What is the primary purpose of a blockchain node's mempool (memory pool) from a security perspective?

Accepted Answer

Holding unconfirmed transactions pending inclusion in a block

Answer

Permanently storing confirmed transactions

Answer

Caching block headers for fast retrieval

Answer

Storing private keys for hot wallets

Question 3

A blockchain node operator notices abnormally high CPU usage caused by peers repeatedly requesting the same large block. Which denial-of-service technique is being used?

Accepted Answer

Bandwidth exhaustion via block re-request flooding

Answer

Replay attack

Answer

Block withholding attack

Answer

Timejacking

Question 4

Which TLS/SSL configuration weakness most directly endangers communications between blockchain node peers over an encrypted channel?

Accepted Answer

Allowing TLS 1.0 with RC4 cipher suites

Answer

Using TLS 1.3 with forward secrecy

Answer

Enforcing mutual certificate authentication

Answer

Using ECDHE key exchange

Question 5

In Ethereum's devp2p protocol, what cryptographic mechanism is used during the initial handshake to establish a shared session key between two nodes?

Accepted Answer

ECDH (Elliptic Curve Diffie-Hellman) with secp256k1

Answer

RSA-2048 key transport

Answer

Pre-shared key (PSK) exchange

Answer

AES-256 ECB mode key wrapping

Question 6

What security risk arises when a blockchain node exposes its JSON-RPC interface on 0.0.0.0 without authentication?

Accepted Answer

Unauthorized callers can drain wallets or manipulate node state

Answer

Increased block propagation latency

Answer

Faster transaction confirmation due to open access

Answer

Automatic firewall rule creation

Question 7

Which network-layer defense is most effective at preventing IP-spoofing-based amplification attacks targeting blockchain gossip protocols?

Accepted Answer

BCP 38 ingress filtering at the ISP or router level

Answer

Increasing block size limits

Answer

Enabling verbose node logging

Answer

Using proof-of-stake consensus