Smart contracts are the foundation of decentralized applications, managing billions of dollars across various blockchain networks. However, vulnerabilities within these contracts have led to substantial financial losses. To address these risks, the OWASP Smart Contract Top 10 provides a structured approach to identifying and mitigating key security issues in smart contract development and deployment.
As a key contributor to this initiative, CredShields has helped define these security standards, ensuring developers and auditors have a structured approach to securing their blockchain infrastructure. This blog will explore each of the OWASP Smart Contract Top 10 vulnerabilities, demonstrate how they have been exploited in real-world attacks, and explain how SolidityScan, our automated security tool, detects and prevents them.
SC01: Access Control Vulnerabilities
Access control vulnerabilities arise when unauthorized users can execute privileged functions due to improper permission enforcement. A notable example is the LAND Token Exploit, where attackers manipulated the updateMiningFee function due to missing access control checks. This allowed unauthorized privilege escalation, resulting in financial losses. Implementing onlyOwner modifiers, role-based access control (RBAC), and multi-signature authentication can prevent such attacks. SolidityScan detects missing access controls and recommends security best practices to mitigate risks. By enforcing strict permission structures, developers can ensure only authorized roles execute critical functions, preventing unauthorized modifications and enhancing smart contract security.
SC02: Price Oracle Manipulation
Price oracle manipulation is a critical vulnerability in DeFi, where attackers exploit unreliable price feeds to execute fraudulent trades. A prime example is the BonqDAO Protocol Hack, where attackers manipulated the Tellor Oracle, artificially inflating token prices and exploiting the system to borrow more than the collateral’s actual worth. This manipulation drained liquidity and led to massive losses. To mitigate such attacks, developers should rely on decentralized oracles like Chainlink and implement circuit breakers to detect price anomalies. SolidityScan helps identify insecure oracles and recommends off-chain verification, ensuring robust protection against manipulation in smart contracts.
SC03: Logic Errors
Errors in smart contract logic can lead to unintended behaviors, and security loopholes. A striking example is the Level Finance Hack, where attackers exploited a flawed reward calculation mechanism in the referral program, repeatedly claiming rewards and draining approximately $1M from the protocol. Such vulnerabilities often arise from poorly implemented contract logic, misconfigured functions, incorrect arithmetic operations, or flawed state updates leading to improper fund distribution and unintended asset transfers. To prevent logic errors, developers should implement formal verification techniques and conduct thorough code reviews before deployment. SolidityScan helps by detecting ambiguous contract logic and recommending improvements to eliminate exploitable misconfigurations and secure smart contracts.
SC04: Lack of Input Validation
Failing to validate user inputs can expose smart contracts to severe exploits, as seen in the Convergence Finance Hack, where attackers manipulated input parameters to execute unintended token swaps. By exploiting unchecked input values, they extracted excess tokens, leading to significant financial losses. Without proper validation, malicious actors can bypass security checks, triggering unintended actions. Implementing strict parameter constraints, sanity checks, and input verification mechanisms can mitigate such risks. SolidityScan helps detect missing input validation in smart contracts and recommends best practices to enforce secure data entry, ensuring robustness against manipulation and unauthorized transactions.
SC05: Reentrancy Attacks
Reentrancy attacks exploit the ability of a malicious contract to repeatedly call a vulnerable function before the previous execution is completed, draining funds in the process. A key example is the Orion Protocol Hack, where attackers manipulated withdrawal functions without proper reentrancy protection, leading to substantial financial losses. By continuously invoking the withdrawal function before balance updates, attackers drained assets multiple times in a single transaction. Implementing reentrancy guards and following the Checks-Effects-Interactions pattern mitigates such risks. SolidityScan detects reentrant function calls and recommends using ReentrancyGuard, ensuring contracts remain secure against recursive exploits.
SC06: Unchecked External Calls
Smart contracts that interact with external addresses without verifying responses are highly vulnerable to exploitation. A notable example is the Punk Protocol exploit, where improper use of delegatecall allowed attackers to execute arbitrary functions in the target contract. Since delegatecall executes code in the caller’s context, malicious contracts could manipulate storage variables and hijack control. Failing to validate return values from external calls can lead to unauthorized fund transfers or unexpected state changes. SolidityScan identifies unchecked return values and unsafe delegate calls, recommending the use of require() or assert() to validate external call responses and prevent exploitation.
SC07: Flash Loan Attacks
Flash loans enable users to borrow large amounts of funds without collateral, making them a powerful tool for both legitimate and malicious purposes. In the DoughFinance exploit, attackers exploited the protocol’s weak validation mechanisms to manipulate asset prices and drain liquidity. The vulnerability arose due to unsecured flash loan execution, allowing the attacker to artificially inflate token values and extract excessive profits. Proper implementation of collateralization checks, time-based transaction limits, and dynamic price oracles can mitigate such risks. SolidityScan helps identify unsecured flash loan mechanisms and recommends robust validation strategies to prevent protocol insolvency and price manipulation attacks.
SC08: Integer Overflow & Underflow
Arithmetic vulnerabilities arise when calculations exceed storage limits, leading to unintended behaviors that attackers can exploit. In the Poolz Finance hack, an integer overflow in the contract’s token vesting function allowed attackers to manipulate input values, triggering an overflow condition that granted them excessive token allocations. This exploit resulted in significant financial losses due to improper arithmetic handling. Upgrading to Solidity 0.8+, which includes built-in overflow and underflow protection, and using libraries like OpenZeppelin’s SafeMath can prevent such vulnerabilities. SolidityScan detects unsafe arithmetic operations and ensures contracts are resilient to overflow and underflow attacks.
SC09: Insecure Randomness
Randomness is crucial for applications like lotteries, gaming, and fair token distribution, but using predictable values can lead to exploits. In the FFIST hack, attackers exploited the predictable nature of the contract’s random number generation, allowing them to manipulate the outcome in their favor. The vulnerability stemmed from the reliance on block timestamps and other on-chain variables, which can be easily influenced by miners. To ensure secure randomness, developers should integrate Chainlink VRF or other decentralized randomness sources. SolidityScan identifies insecure randomness implementations and recommends secure entropy sources to protect against manipulation and unfair advantages.
SC10: Denial of Service (DoS) Attacks
A Denial of Service (DoS) attack can render a smart contract unusable by exhausting gas limits, blocking function execution, or creating infinite loops. Developers should limit loop iterations, optimize gas usage, and use off-chain computations where possible. SolidityScan flags unbounded loops and inefficient computations that could lead to DoS vulnerabilities.
To ensure an accurate representation of real-world threats, the OWASP Smart Contract Top 10 for 2025 was built upon insights from SolidityScan’s Web3HackHub (2024), Peter Kacherginsky’s “Top 10 DeFi Attack Vectors – 2024”, and the Immunefi Crypto Losses in 2024 Report. These sources document 149 security incidents that resulted in $1.42 billion in financial losses across decentralized ecosystems, providing a critical foundation for prioritizing the most significant threats.
The OWASP Smart Contract Top 10 serves as a fundamental security framework for protecting blockchain applications. As a major contributor to this standard, CredShields is committed to ensuring Web3 security through automated vulnerability detection with SolidityScan. By implementing these best practices, developers can prevent catastrophic financial losses and strengthen trust in decentralized ecosystems.