Blockchain Developer FREE Blockchain Developer Blockchain Security and Vulnerabilities Questions and Answers 2

Question 1

What is a flash loan attack in DeFi?

Accepted Answer

Exploiting uncollateralized loans within a single transaction to manipulate protocol state

Answer

Stealing private keys from a lending protocol

Answer

Draining funds by sending multiple small transactions rapidly

Answer

Attacking the consensus layer of a blockchain network

Question 2

Which vulnerability does the Checks-Effects-Interactions pattern specifically prevent?

Accepted Answer

Reentrancy attacks

Answer

Integer overflow

Answer

Front-running

Answer

Denial of service

Question 3

What is transaction front-running on a blockchain?

Accepted Answer

Submitting a transaction with higher gas to execute before a pending target transaction

Answer

Reversing a confirmed transaction by forking the chain

Answer

Injecting malicious code into a pending transaction

Answer

Sending duplicate transactions to congest the mempool

Question 4

What is the primary risk of using tx.origin for authentication in Solidity?

Accepted Answer

A malicious intermediate contract can pass the tx.origin check of the original sender

Answer

It returns the zero address for contract calls

Answer

It can be spoofed by any externally owned account

Answer

It consumes significantly more gas than msg.sender

Question 5

Which attack vector targets the random number generation in smart contracts that use block variables?

Accepted Answer

Block timestamp manipulation by miners

Answer

Sybil attack

Answer

Replay attack

Answer

Eclipse attack

Question 6

What does a sandwich attack in DeFi involve?

Accepted Answer

Placing transactions both before and after a victim's swap to profit from the price impact

Answer

Wrapping a malicious token inside a legitimate token contract

Answer

Layering multiple flash loans across different protocols

Answer

Exploiting two different DEXs simultaneously for arbitrage