Solidity Solidity Security and Vulnerabilities

Question 1

Which attack exploits a contract that calls an external contract before updating its state?

Accepted Answer

Reentrancy attack

Answer

Front-running attack

Answer

Overflow attack

Answer

Denial of service attack

Question 2

What is the recommended pattern to prevent reentrancy attacks in Solidity?

Accepted Answer

Checks-Effects-Interactions pattern

Answer

Factory pattern

Answer

Proxy pattern

Answer

Observer pattern

Question 3

What Solidity modifier from OpenZeppelin prevents reentrancy by locking the function?

Accepted Answer

nonReentrant

Answer

onlyOwner

Answer

whenNotPaused

Answer

safeCall

Question 4

Which vulnerability allows an attacker to manipulate transaction ordering to their advantage?

Accepted Answer

Front-running (MEV)

Answer

Integer overflow

Answer

Reentrancy

Answer

Delegatecall injection

Question 5

What is the danger of using `tx.origin` for authentication in Solidity?

Accepted Answer

It can be spoofed via phishing contracts to impersonate users

Answer

It costs more gas than msg.sender

Answer

It is deprecated in Solidity 0.8

Answer

It only works with EOAs

Question 6

What is a 'griefing' attack in the context of smart contract security?

Accepted Answer

An attack that causes a contract to revert or waste gas without direct profit to the attacker

Answer

An attack that steals ETH from a contract

Answer

An attack that upgrades a proxy to malicious code

Answer

An attack that drains ERC-20 allowances