Solidity Solidity Security and Vulnerabilities 2

Question 1

What vulnerability arises when Solidity arithmetic operations exceed the maximum or minimum value of the data type?

Accepted Answer

Integer overflow/underflow

Answer

Integer overflow/underflow occurs when arithmetic results exceed the bounds of the integer type, wrapping around to unexpected values.

Question 2

In Solidity 0.8.x, what happens when an arithmetic overflow occurs by default?

Accepted Answer

The transaction reverts automatically

Answer

Solidity 0.8 introduced built-in checked arithmetic, so overflow/underflow automatically reverts the transaction instead of wrapping values.

Question 3

What attack vector is created when a contract uses `block.timestamp` as a source of randomness?

Accepted Answer

Miners can slightly manipulate the timestamp to influence the outcome

Answer

Miners (or validators) have limited ability to adjust `block.timestamp`, allowing them to influence randomness-dependent outcomes like lotteries.

Question 4

What is a 'flash loan attack' in the context of DeFi smart contracts?

Accepted Answer

Exploiting price oracles or governance by borrowing large sums within a single transaction

Answer

Flash loan attacks use uncollateralized loans borrowed and repaid within one transaction to manipulate market prices or governance votes.

Question 5

What is the risk of using `delegatecall` to an untrusted contract?

Accepted Answer

The callee can overwrite the caller's storage with malicious data

Answer

With `delegatecall`, the called contract's code runs in the caller's storage context, so a malicious callee can corrupt or drain the caller's state.

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