Fundamentals of Blockchain Security 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 Fundamentals of Blockchain Security flashcards as text
What is a smart contract reentrancy attack?
Answer: Calling a contract function repeatedly before its state updates to drain funds
Reentrancy exploits a contract that makes external calls before updating its balance, allowing repeated withdrawals.
Which design principle helps prevent reentrancy vulnerabilities?
Answer: Checks-Effects-Interactions pattern
Updating internal state before making external calls (checks-effects-interactions) blocks reentrant withdrawals.
What is the security risk of an unaudited smart contract holding user funds?
Answer: Hidden bugs or backdoors may allow theft with no way to patch easily
Immutable, unaudited contracts can contain exploitable flaws that are difficult or impossible to fix once deployed.
What is an integer overflow vulnerability in smart contracts?
Answer: A value exceeding its maximum wraps around to an unexpected number
When arithmetic exceeds a variable's max range it wraps around, which attackers can exploit to manipulate balances.
Why is the 'gas' mechanism important for smart contract security?
Answer: It limits computation to prevent infinite loops and resource exhaustion
Gas caps the work a transaction can do, stopping infinite loops and denial-of-service from runaway code.
What is a front-running attack in a blockchain context?
Answer: Submitting a transaction with higher fees to execute before a pending one
Front-running exploits public mempool visibility by paying more gas to get a transaction ordered ahead of another.
What practice most reduces risk before deploying a smart contract to mainnet?
Answer: Conducting thorough audits and testing on a testnet
Independent audits and testnet trials catch vulnerabilities before real funds are at risk.