CVE-2018-13640 in EthereumSmart
Summary
by MITRE
The mintToken function of a smart contract implementation for EthereumSmart, an Ethereum token, has an integer overflow that allows the owner of the contract to set the balance of an arbitrary user to any value.
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Analysis
by VulDB Data Team • 02/28/2020
The mintToken function in the Ethereum Smart token smart contract contains a critical integer overflow vulnerability that fundamentally compromises the contract's integrity and security model. This flaw exists within the core token issuance mechanism where the contract owner can manipulate user balances through improper integer arithmetic handling. The vulnerability arises when the mintToken function performs operations that exceed the maximum value representable by the integer data type, creating a scenario where arithmetic operations wrap around to unexpected values. This represents a classic integer overflow condition that violates fundamental security principles and enables malicious behavior through crafted input parameters.
The technical implementation of this vulnerability stems from the lack of proper overflow checks within the mintToken function's arithmetic operations. When the contract processes token minting requests, it likely performs calculations involving user balances or token supply without validating that these operations remain within safe integer boundaries. The underlying issue manifests when the contract attempts to increment a user's balance or update the total supply, causing the integer to wrap around to zero or negative values when exceeding maximum limits. This behavior directly violates the expected mathematical properties of integer arithmetic and creates a pathway for arbitrary balance manipulation that bypasses normal contract validation mechanisms. The vulnerability is particularly dangerous because it allows the contract owner to directly set any user's balance to any desired value, effectively enabling unauthorized fund manipulation and potentially complete contract compromise.
The operational impact of this vulnerability extends far beyond simple balance manipulation, creating significant risks for token holders and the overall ecosystem. An attacker with owner privileges can exploit this flaw to inflate user balances, create artificial token distributions, or even drain contract funds by manipulating the total supply calculations. The vulnerability undermines the fundamental trust model of Ethereum tokens where users expect their balances to be accurately maintained and where contract operations follow predictable mathematical behavior. This issue creates potential for financial loss, contract manipulation, and systematic compromise of the token's economic model. The vulnerability also enables potential denial of service scenarios where an attacker could manipulate balances to prevent normal transaction processing or create impossible states within the contract. Such exploitation directly impacts the security posture of the entire token ecosystem and can result in significant financial damage to users and the project itself.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. The recommended approach involves incorporating explicit overflow checks before any arithmetic operations that could potentially exceed integer limits, utilizing safe math libraries or built-in overflow protection features available in modern Solidity versions. The contract owner must ensure that all balance updates and supply calculations include proper validation to prevent wraparound behavior. Additionally, implementing comprehensive testing procedures including fuzz testing and formal verification can help identify similar vulnerabilities before deployment. The solution aligns with security best practices outlined in the CWE-190 category for integer overflow and underflow conditions, and addresses ATT&CK techniques related to privilege escalation and resource hijacking. Regular security audits and code reviews should be implemented to prevent similar issues in future contract deployments, ensuring that all mathematical operations within smart contracts maintain proper boundary checks and validation mechanisms.