Mitigating Blockchain Attacks and Security Practices BFC Practice Questions (Page 10)

Questions 46–48

1. 46foundation · easy

   A smart contract uses a uint8 variable to store a counter. If the counter is at 255 and the contract adds 1, what type of vulnerability occurs?

   • APhishing
   • BInteger overflow
   • CReentrancy
   • DLogic flaw
   Reveal Solution Discussion Select an answer first
2. 47foundation · easy

   Which step in a blockchain-specific incident response plan is unique compared to traditional IT incident response?

   • ANotifying law enforcement
   • BIdentifying affected systems and data
   • CRestoring from backups
   • DDetermining whether a hard fork or chain rollback is necessary
   Reveal Solution Discussion Select an answer first
3. 48application · medium

   A DeFi protocol allows users to deposit tokens and then withdraw their balance. A security audit finds that the withdrawal function updates the user's balance only after transferring tokens. Which vulnerability does this code pattern most likely exhibit, and what is the recommended remediation?

   • AInteger overflow; use SafeMath or Solidity 0.8+ built-in overflow checks.
   • BDenial-of-service; implement a withdrawal limit per block.
   • CLogic flaw; require a multi-signature wallet for all withdrawals.
   • DReentrancy; use a checks-effects-interactions pattern or a reentrancy guard.
   Reveal Solution Discussion Select an answer first