Mitigating Blockchain Attacks and Security Practices BFC Practice Questions (Page 3)

Questions 11–15

1. 11application · medium

   A blockchain network uses a delegated proof-of-stake (DPoS) consensus where token holders vote for a small set of block producers. A security assessment finds that a few wealthy token holders could collude to control the block producers. Which mitigation is most effective?

   • ARemove voting entirely and let the development team choose block producers.
   • BIncrease the number of block producers to thousands.
   • CAllow block producers to be anonymous to prevent targeting.
   • DImplement a voting mechanism that weights votes by reputation and time-locked tokens, not just token balance.
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A small fintech consortium runs a permissioned blockchain with only five validator nodes, all operated by member banks. A security analyst warns that an attacker who compromises two of the five nodes could manipulate transaction history. Which additional control would most directly reduce this risk?

   • AImplement a replay attack protection mechanism in the transaction format
   • BIncrease the validator set to 15 nodes across diverse jurisdictions
   • CEnable TLS for all peer-to-peer communication between nodes
   • DDeploy a hardware security module (HSM) at each validator site
   Reveal Solution Discussion Select an answer first
4. 13foundation · easy

   Which blockchain attack occurs when a single entity or group gains control of more than half of the network's mining or staking power, allowing them to double-spend or prevent new transactions from confirming?

   • ASybil attack
   • BReplay attack
   • C51% attack
   • DPhishing attack
   Reveal Solution Discussion Select an answer first
5. 14expert · hard

   A decentralized finance (DeFi) protocol has a tight deadline to launch. The team has budget for either a comprehensive third-party audit or a bug bounty program, but not both. The protocol handles large sums of user funds and has complex interactions with external contracts. Which choice is more prudent?

   • ALaunch immediately and rely on a bug bounty program to find vulnerabilities after launch.
   • BRun a bug bounty program before launch to get community input.
   • CSkip both and rely on the development team's internal testing.
   • DConduct a comprehensive third-party audit before launch, even if it delays the launch.
   Reveal Solution Discussion Select an answer first
6. 15expert · hard

   A permissioned blockchain network with 10 validators has experienced a Sybil attack where an attacker created many fake identities to gain multiple validator slots. The governance board wants to prevent this in the future while maintaining decentralization. Which approach is most effective?

   • AImplement a proof-of-work requirement for validator registration
   • BIncrease the number of validators to 100
   • CUse a centralized identity provider to verify each validator
   • DRequire validators to stake a significant amount of the network's native token
   Reveal Solution Discussion Select an answer first