Auditing, Testing, and Monitoring in Blockchain Security BDC Practice Questions (Page 5)

Questions 21–25

1. 21application · medium

   A DeFi protocol uses a price oracle that reads from a single DEX pool. An auditor is evaluating the risk of oracle manipulation. Which mitigation would be most effective?

   • AUse the latest price from the single DEX pool but add a delay before it is used.
   • BUse a time-weighted average price (TWAP) from multiple independent sources or a decentralized oracle network.
   • CIncrease the gas limit for transactions that call the oracle.
   • DAdd a reentrancy guard to the contract that reads the oracle.
   Reveal Solution Discussion Select an answer first
2. 22application · medium

   A blockchain-based supply chain platform has been live for six months. The security team wants to implement monitoring to detect suspicious activity, such as unauthorized access or abnormal transaction patterns. Which monitoring approach is most effective?

   • AReview the blockchain's transaction history once a month to identify any suspicious patterns.
   • BSet up real-time monitoring of on-chain transactions and off-chain access logs, with alerts for anomalies and a defined incident response plan.
   • CMonitor only the off-chain database logs, because the blockchain itself is immutable and secure.
   • DRely on the blockchain's consensus mechanism to automatically prevent all malicious activity.
   Reveal Solution Discussion Select an answer first
4. 23foundation · easy

   Which element is typically included in the objectives of a blockchain security audit?

   • AGuaranteeing that the system is free from all possible attacks
   • BProviding a legal opinion on regulatory compliance
   • CEnsuring the system's token price remains stable
   • DIdentifying vulnerabilities and assessing risks to the system's security
   Reveal Solution Discussion Select an answer first
5. 24application · medium

   During an audit, you find a function that uses `msg.sender` to authorize an action. You suspect an access control flaw. Which testing technique would best confirm this?

   • AWrite a unit test that calls the function from an unauthorized account and checks that it reverts
   • BDeploy the contract on a testnet and call it from a different account
   • CPerform a manual review of the function
   • DRun a static analyzer to detect the use of `msg.sender`
   Reveal Solution Discussion Select an answer first
6. 25expert · hard

   A proof-of-work blockchain is experiencing a drop in hash rate, and the security team is concerned about a potential 51% attack. They need to decide whether to implement additional monitoring. Which action is most appropriate?

   • AIncrease monitoring of the network's hash rate distribution and block production, and set alerts for unusual patterns such as a sudden increase in blocks from a single miner.
   • BIgnore the drop in hash rate, because 51% attacks are only theoretical.
   • CImmediately switch the consensus mechanism to proof-of-stake to prevent the attack.
   • DIncrease the block reward to attract more miners and raise the hash rate.
   Reveal Solution Discussion Select an answer first