CVE-2018-13730 in HEY
Summary
by MITRE
The mintToken function of a smart contract implementation for HEY, 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 vulnerability identified as CVE-2018-13730 represents a critical integer overflow flaw within the mintToken function of an Ethereum token smart contract implementation known as HEY. This vulnerability resides in the fundamental arithmetic operations of the smart contract code where insufficient input validation and overflow protection mechanisms exist. The flaw allows an attacker with owner privileges to manipulate token balances by setting them to arbitrary values, effectively compromising the integrity of the token economy. The vulnerability stems from improper handling of unsigned integer arithmetic where the contract fails to validate that operations do not exceed the maximum value representable by the data type, creating a condition where mathematical overflow can occur without proper bounds checking.
The technical implementation of this vulnerability demonstrates a classic case of insufficient input validation and arithmetic overflow protection within smart contract code. When the mintToken function processes token minting operations, it performs calculations that do not properly check for overflow conditions before executing arithmetic operations. This creates a scenario where an attacker can manipulate the underlying integer values to produce unexpected results, particularly when dealing with large token amounts or specific value combinations. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, which is a well-documented weakness in software development that becomes particularly dangerous in blockchain environments where financial assets are at stake. The attack vector specifically targets the owner account privileges, requiring an attacker to gain control of the contract owner role to exploit this vulnerability effectively.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token ecosystem and user trust in the platform. An attacker with owner privileges can arbitrarily increase or decrease any user's token balance, leading to scenarios such as unlimited token generation, unauthorized balance transfers, or complete disruption of the token's economic model. This vulnerability directly affects the core principles of blockchain security including asset integrity, access control, and trustless execution. The consequences can be severe for token holders who may lose their assets, and for the broader ecosystem which depends on predictable and secure smart contract behavior. From an attacker's perspective, this represents a high-value target as it provides direct control over token distribution and can potentially lead to financial loss for all stakeholders.
Mitigation strategies for CVE-2018-13730 should focus on implementing comprehensive input validation and arithmetic overflow protection mechanisms within smart contract code. The primary remediation involves adding proper bounds checking and overflow detection before any arithmetic operations, particularly in functions that handle token minting or balance modifications. Developers should utilize modern smart contract development frameworks and libraries that provide built-in overflow protection mechanisms such as OpenZeppelin's SafeMath library. Additionally, contract owner privileges should be carefully managed through multi-signature wallets, time locks, and proper access control mechanisms to reduce the risk of unauthorized access. Regular security audits and formal verification of smart contract code should be implemented to identify and address similar vulnerabilities before they can be exploited. The remediation process should also include thorough testing of edge cases and boundary conditions to ensure that all possible overflow scenarios are properly handled, aligning with the principles of secure software development practices and industry standards for blockchain security.