Common Threats and Blockchain Security Best Practices BBLC Practice Questions (Page 9)

Questions 41–45

1. 41foundation · easy

   Which of the following best describes a 51% attack on a proof-of-work blockchain?

   • AAn attacker exploits a vulnerability in a smart contract to drain funds from users.
   • BAn attacker sends a large number of transactions to overwhelm the network and cause denial of service.
   • CAn attacker gains control of more than half of the network's mining hash rate, allowing them to prevent new transactions from confirming and potentially reverse recently confirmed transactions.
   • DAn attacker creates numerous fake identities to influence voting or governance mechanisms within the blockchain network.
   Reveal Solution Discussion Select an answer first
2. 42application · medium

   A small blockchain consortium runs a permissioned network with only five validator nodes, all operated by the same hosting provider. A member company is concerned about a 51% attack. Which measure would most directly reduce the risk of a 51% attack in this network?

   • AImplement a longer block time to give the network more time to detect malicious blocks.
   • BAdd a firewall rule that only allows validator traffic from the hosting provider's IP range.
   • CIncrease the number of validator nodes and distribute them across independent organizations and geographic regions.
   • DRequire all validators to use hardware security modules (HSMs) to store their private keys.
   Reveal Solution Discussion Select an answer first
4. 43foundation · easy

   Which activity is typically part of a security audit for a blockchain system?

   • AReviewing the codebase for known vulnerabilities and insecure patterns.
   • BIncreasing the block size to improve scalability.
   • CMinting new tokens to reward users.
   • DDeploying the system to a public cloud for testing.
   Reveal Solution Discussion Select an answer first
5. 44application · medium

   A company runs a blockchain node infrastructure that is exposed to the internet. They have experienced a distributed denial-of-service (DDoS) attack that overwhelmed their nodes. Which set of measures would best protect the nodes from future DDoS attacks while maintaining availability?

   • AIncrease the node's bandwidth and CPU resources to absorb the attack traffic.
   • BDisable the node's public API and only allow access from a VPN.
   • CPlace the nodes behind a DDoS-protection service and restrict access to the node's peer-to-peer (P2P) port to known peers.
   • DUse a firewall to block all incoming traffic except from a whitelist of IP addresses.
   Reveal Solution Discussion Select an answer first
6. 45application · medium

   A cryptocurrency exchange has seen an increase in customers falling victim to phishing attacks, where they enter their login credentials on fake websites. The exchange wants to reduce this risk. Which user education initiative would be most effective?

   • AConduct simulated phishing campaigns and provide immediate feedback to users who fall for them.
   • BSend a monthly newsletter that includes general cybersecurity tips.
   • CDisplay a warning on the exchange's website that phishing is dangerous.
   • DRequire users to watch a video about blockchain technology before using the exchange.
   Reveal Solution Discussion Select an answer first