Smart Contract Risks BFC Practice Questions (Page 4)

Questions 16–20

1. 16foundation · easy

   Which type of smart contract vulnerability occurs when an arithmetic operation produces a value that exceeds the maximum size of the data type, leading to unexpected results?

   • ATimestamp dependence
   • BPhishing
   • CInteger overflow
   • DReentrancy
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   Which risk mitigation strategy involves mathematically proving that a smart contract behaves correctly for all possible inputs?

   • ACode audit
   • BFormal verification
   • CPenetration testing
   • DBug bounty program
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   A decentralized insurance platform relies on an external oracle to fetch weather data for triggering crop insurance payouts. The oracle occasionally reports stale data, causing incorrect payouts. What is the most effective risk mitigation approach?

   • ARemove the oracle and rely on manual claims processing
   • BHardcode the weather data into the contract
   • CIncrease the frequency of oracle updates
   • DUse a decentralized oracle network with multiple data sources and aggregation
   Reveal Solution Discussion Select an answer first
5. 19expert · hard

   A DeFi protocol has a smart contract that allows users to deposit and withdraw funds. A recent audit found that the contract is vulnerable to a reentrancy attack. The team is torn between two fixes: adding a reentrancy guard or moving all state updates before external calls. Which approach is the most robust?

   • ARely on the compiler's built-in protections
   • BOnly use the check-effects-interactions pattern
   • COnly add a reentrancy guard
   • DImplement both a reentrancy guard and the check-effects-interactions pattern
   Reveal Solution Discussion Select an answer first
6. 20expert · hard

   A smart contract for a decentralized options exchange has a function that allows users to claim rewards. The function uses a mapping to track claimed amounts. A security researcher finds that an attacker can call the function multiple times before the mapping is updated, claiming more rewards than entitled. What is the most effective fix?

   • AUpdate the mapping before making any external calls
   • BUse a higher gas limit for the function
   • CAdd a require statement to check the caller's balance
   • DMake the function private
   Reveal Solution Discussion Select an answer first