Smart Contract Vulnerabilities: A Comprehensive Guide for Blockchain Developers

Question 1

Which vulnerability enables an attacker to control a smart contract's execution by repeatedly calling it before the initial call finishes?

Accepted Answer

Reentrancy Attack

Answer

Buffer Overflow

Answer

Integer Underflow

Question 2

In the context of smart contracts, which vulnerability allows an attacker to execute malicious actions by recursively calling the same function multiple times?

Accepted Answer

Reentrancy

Answer

Arithmetic Overflow

Answer

Uninitialized Variable

Answer

Typosquatting

Question 3

What type of vulnerability occurs when an attacker manipulates the order of transactions to gain an unfair advantage?

Accepted Answer

Front-running

Answer

Sybil Attack

Answer

Pump and Dump

Answer

Rug Pull

Question 4

Which type of attack aims to disrupt or disable a smart contract by flooding it with excessive requests?

Accepted Answer

Denial of Service (DoS)

Answer

Replay Attack

Answer

Timing Attack

Answer

Man-in-the-Middle

Question 5

Which vulnerability results from relying on external data sources or services that can be manipulated or compromised, affecting the correctness of smart contract execution?

Accepted Answer

Oracle

Answer

Randomness

Answer

Block Explorer

Answer

Timestamp

Question 6

Which type of vulnerability arises from flaws in the logic of a smart contract, leading to unintended behavior or security risks?

Accepted Answer

Logic Flaw

Answer

Semantic Ambiguity

Answer

Physical Vulnerability

Answer

Syntax Error

Question 7

What vulnerability allows an attacker to alter the intended recipient or amount of a transaction by exploiting typos or similar techniques?

Accepted Answer

Typosquatting

Answer

Social Engineering

Answer

Phishing

Answer

Spam

Question 8

Which type of vulnerability arises due to insufficient input validation, allowing attackers to inject malicious code or data into a smart contract?

Accepted Answer

Injection

Answer

Deserialization

Answer

Buffer Overflow

Answer

Cross-site Scripting

Question 9

What vulnerability occurs when a smart contract operates on a variable that has not been assigned a value, leading to undefined behavior?

Accepted Answer

Uninitialized Variable

Answer

Unbound Variable

Answer

Ambiguous Variable

Answer

Misinterpreted Variable

Question 10

In the context of smart contracts, which type of attack exploits a reentrant function that can be called multiple times during the execution of a single transaction?

Accepted Answer

Reentrancy attack

Answer

Phishing attack

Answer

Replay attack

Answer

DoS attack

Question 11

What is the primary purpose of using a transaction hash in a smart contract?

Accepted Answer

To ensure the integrity and authenticity of a transaction

Answer

To store the transaction data permanently

Answer

To track the status of a transaction

Answer

To facilitate communication between smart contracts

Question 12

What is a common cause of integer overflow vulnerabilities in smart contracts?

Accepted Answer

Storing large values in variables with insufficient bit size

Answer

Incorrectly handling negative values

Answer

Calling external functions with untrusted inputs

Answer

Using floating-point arithmetic

Question 13

In the context of smart contract security, what term refers to restricting access to certain functions or data based on predefined roles or permissions?

Accepted Answer

Access control

Answer

Data validation

Answer

Event handling

Answer

Gas optimization

Question 14

Which vulnerability arises from failing to validate input data received from external sources?

Accepted Answer

Input validation vulnerability

Answer

Integer overflow vulnerability

Answer

Reentrancy vulnerability

Answer

Access control vulnerability

Question 15

What is the purpose of setting a gas limit in a smart contract?

Accepted Answer

To prevent infinite loops and excessive gas consumption

Answer

To control the maximum amount of Ether that can be transferred

Answer

To limit the number of transactions that can be processed

Question 16

Which type of vulnerability refers to the ability of an attacker to modify the state of a smart contract after it has been deployed?

Accepted Answer

Upgradability vulnerability

Answer

Access control vulnerability

Answer

Integer overflow vulnerability

Answer

Transaction handling vulnerability

Question 17

What is the primary benefit of using a unit testing framework in smart contract development?

Accepted Answer

To test individual functions and modules in isolation

Answer

To generate test data for smart contract inputs

Answer

To simulate the entire blockchain network

Question 18

Common smart contract vulnerabilities do NOT include:

Accepted Answer

Syntactic Errors

Answer

Reentrancy Attacks

Answer

Integer Overflow

Answer

Front-Running

Question 19

A smart contract function susceptible to being called multiple times before the previous execution finishes is vulnerable to:

Accepted Answer

Reentrancy Attack

Answer

Phishing

Answer

Race Condition

Answer

DoS Attack

Question 20

A vulnerability that enables attackers to modify the timestamp of a smart contract for an unfair advantage is known as:

Accepted Answer

Timestamp Manipulation

Answer

DoS Attack

Answer

Replay Attack

Answer

Phishing

Question 21

What is a key benefit of employing fuzz testing to identify smart contract vulnerabilities?

Accepted Answer

Generation of Unanticipated Input

Answer

Minimized False Positives

Answer

Efficient Execution

Answer

Deterministic Results

Question 22

A smart contract relying on user input for critical decisions without proper checks can be vulnerable to:

Accepted Answer

Input Validation

Answer

Overflow

Answer

Concurrency

Answer

Reentrancy Attack

Question 23

Which mechanism can prevent unauthorized access to a smart contract's state variables?

Accepted Answer

Access Control Modifiers

Answer

Unit Testing

Answer

Fuzz Testing

Answer

Event Logging

Question 24

A smart contract dependent on external data sources without verifying their integrity is susceptible to:

Accepted Answer

Data Integrity Attacks

Answer

Phishing

Answer

Reentrancy Attacks

Answer

DoS Attacks

Question 25

A recommended practice for writing secure smart contracts is:

Accepted Answer

Utilizing Open Source Libraries

Answer

Composing Lengthy and Complex Code

Answer

Avoiding External Data Usage

Answer

Ignoring Code Audits

Question 26

Smart contract deployment with incorrect or insecure parameters may result in:

Accepted Answer

Parameter Manipulation

Answer

Phishing

Answer

DoS Attacks

Answer

Gas Optimization