Security and Attacks Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Security and Attacks flashcards as text
What is a 'selfish mining' attack in blockchain networks?
Answer: A miner hoards discovered blocks and releases them strategically to waste honest miners' work
Selfish mining withholds blocks to make honest miners waste effort on orphaned chains, giving the attacker a disproportionate share of rewards.
Which attack exploits the time gap between when a smart contract checks a condition and when it executes the action?
Answer: Time-of-check to time-of-use (TOCTOU) attack
A TOCTOU attack exploits the window between a condition check and execution, allowing state to change in between.
What does a 'dust attack' target in cryptocurrency networks?
Answer: Mining pool coordination by sending tiny amounts to wallets to de-anonymize owners
Dust attacks send tiny amounts ('dust') to many addresses, then trace how those funds move to cluster addresses and break pseudonymity.
What is the primary risk of using weak random number generation in a blockchain smart contract?
Answer: Predictable outcomes that attackers can exploit before transactions confirm
Weak randomness (e.g., using block hash or timestamp) is predictable by miners, allowing them to manipulate lottery or gambling contract outcomes.
In blockchain security, what is an 'eclipse attack'?
Answer: Intercepting a node's network connections so it only communicates with attacker-controlled peers
An eclipse attack isolates a node by controlling all its peer connections, feeding it false information about the blockchain state.
What vulnerability does 'integer overflow' create in Ethereum smart contracts?
Answer: Values wrap around to unintended numbers, enabling exploits like minting unlimited tokens
Integer overflow causes arithmetic values to wrap around (e.g., max uint256 + 1 = 0), which attackers exploit to create massive balances from near-zero amounts.
Which technique do attackers use in a 'sandwich attack' on decentralized exchanges?
Answer: Place a buy order before and a sell order after a victim's large trade to profit from price impact
A sandwich attack front-runs a victim's trade to push the price up, then back-runs it to sell at a profit, exploiting the victim's price slippage.