Attack Surfaces in Blockchain Ecosystems BDC Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   A DeFi lending protocol uses a price oracle that aggregates data from three centralized exchanges. An attacker notices that the oracle only updates every 10 minutes and that the protocol's flash-loan feature allows borrowing large amounts without collateral within a single transaction. What is the most direct risk this configuration exposes?

   • AThe attacker can perform a reentrancy attack on the lending contract by repeatedly calling the flash-loan function before the previous call completes.
   • BThe attacker can manipulate the oracle price by placing large orders on one exchange, then use a flash loan to borrow against the inflated collateral value before the oracle updates.
   • CThe attacker can cause a 51% attack on the underlying blockchain by using flash loans to acquire enough native tokens to control consensus.
   • DThe attacker can launch an eclipse attack on the oracle nodes to feed false price data to the protocol.
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   Which consensus attack involves a miner or mining pool keeping newly found blocks private to gain a competitive advantage?

   • AEclipse attack
   • BSelfish mining
   • CSybil attack
   • DLong-range attack
   Reveal Solution Discussion Select an answer first
4. 18application · easy

   A smart contract has an `owner` variable that is set during deployment. The contract has a function `changeOwner` that does not check if the caller is the current owner. An attacker calls this function and sets the owner to their own address. What type of vulnerability is this?

   • AAccess control flaw
   • BOracle manipulation
   • CInteger overflow
   • DReentrancy vulnerability
   Reveal Solution Discussion Select an answer first
5. 19foundation · easy

   What is an eclipse attack on a blockchain node?

   • AAn attacker creates many fake identities to gain network influence
   • BAn attacker exploits a smart contract bug to drain funds
   • CAn attacker surrounds a target node with malicious peers, controlling its view of the network
   • DAn attacker floods the network with spam transactions
   Reveal Solution Discussion Select an answer first
6. 20foundation · easy

   In the context of a blockchain ecosystem, what does the term 'attack surface' refer to?

   • AThe portion of the blockchain ledger that is encrypted and inaccessible to unauthorized users
   • BThe list of known vulnerabilities that have been publicly disclosed for a specific blockchain
   • CThe graphical representation of network topology used for monitoring node connectivity
   • DThe total set of points in the system where an unauthorized user could try to enter or extract data
   Reveal Solution Discussion Select an answer first