CCA Smart Contract Auditing 2

Question 1

Which smart contract vulnerability allows an attacker to repeatedly call a function and drain funds before the initial execution updates the contract state?

Accepted Answer

Reentrancy

Answer

Reentrancy occurs when an external call is made before state updates, allowing attackers to re-enter the function and repeatedly withdraw funds.

Question 2

What is the primary purpose of a 'checks-effects-interactions' pattern in Solidity smart contracts?

Accepted Answer

To prevent reentrancy attacks by updating state before external calls

Answer

The checks-effects-interactions pattern mitigates reentrancy by performing checks, then updating state (effects), and only then making external calls (interactions).

Question 3

During a smart contract audit, you identify that a mapping is never deleted after funds are transferred. What risk does this pose?

Accepted Answer

Unbounded storage growth leading to excessive gas costs

Answer

Unmaintained mappings cause unbounded state growth that increases storage costs and can make contract operations prohibitively expensive over time.

Question 4

Which tool is specifically designed for formal verification of Ethereum smart contracts?

Accepted Answer

Certora Prover

Answer

Certora Prover uses formal verification to mathematically prove that a smart contract satisfies specified properties under all conditions.

Question 5

A smart contract uses `tx.origin` for authentication. What attack does this enable?

Accepted Answer

Phishing via malicious intermediary contract

Answer

`tx.origin` returns the original transaction sender, so a malicious contract can trick the original user into calling it, then use `tx.origin` to impersonate them.

(CCA) Certified Cryptocurrency Auditor Practice Test

(CCA) Certified Cryptocurrency Auditor Practice Test

CCA Smart Contract Auditing 2