Common Threats and Blockchain Security Best Practices BBLC Practice Questions (Page 7)

Questions 31–35

1. 31expert · hard

   A company runs a permissioned blockchain for cross-border payments. They have just discovered that a validator node has been compromised and is signing invalid transactions. The incident response team must act quickly. The network has 7 validators, and the compromised node is one of them. The team has the following options. Which is the BEST immediate action?

   • AIgnore the issue and continue operating, as one node cannot cause much harm.
   • BTemporarily remove the compromised validator from the consensus set and rotate its keys.
   • CShut down the entire blockchain network to prevent further damage.
   • DIncrease the block reward to incentivize the compromised node to behave.
   Reveal Solution Discussion Select an answer first
2. 32application · medium

   A user wants to prove to a third party that they own a specific blockchain address without revealing their private key. Which cryptographic technique should they use?

   • AUse a hash of the private key as a password.
   • BCreate a digital signature over a message using their private key.
   • CPublish the private key on a public forum.
   • DSend the private key to the third party in an encrypted email.
   Reveal Solution Discussion Select an answer first
4. 33application · medium

   A company has developed a smart contract that will manage a large amount of value. Before deploying it to the mainnet, they want to identify vulnerabilities. Which approach provides the most comprehensive assurance?

   • AAsk the developer who wrote the contract to review it themselves.
   • BConduct both an automated security scan and a manual code review by independent auditors.
   • CRun the contract on a testnet and observe if any transactions fail.
   • DUse a code obfuscator to make the contract difficult to understand.
   Reveal Solution Discussion Select an answer first
5. 34application · medium

   A company's employees frequently receive emails that appear to be from the company's blockchain wallet provider, asking them to 'verify' their account by clicking a link and entering their private key. Several employees have complied. Which additional measure would be MOST effective to reduce this risk?

   • ARequire employees to use a password manager to store their private keys.
   • BDisable email for all employees.
   • CBlock the wallet provider's domain in the company firewall.
   • DConduct regular security awareness training that includes simulated phishing campaigns.
   Reveal Solution Discussion Select an answer first
6. 35foundation · easy

   Which threat vector is most directly exploited by a smart contract vulnerability such as a reentrancy attack?

   • AThe network's consensus mechanism.
   • BThe user's private key storage.
   • CThe logic of the smart contract code itself.
   • DThe physical security of mining hardware.
   Reveal Solution Discussion Select an answer first