CVE-2018-13641 in MVGcoin
Summary
by MITRE
The mintToken function of a smart contract implementation for MVGcoin, 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 in CVE-2018-13641 represents a critical integer overflow flaw within the mintToken function of the MVGcoin Ethereum smart contract implementation. This vulnerability stems from improper input validation and arithmetic handling within the smart contract code, creating a scenario where the contract owner can manipulate user balances arbitrarily. The integer overflow occurs when the contract attempts to increment token balances without adequate bounds checking, allowing for wraparound behavior that can result in unintended balance modifications. Such a flaw fundamentally undermines the integrity of the token economy by enabling unauthorized balance manipulation that could be exploited for financial gain or system disruption.
The technical execution of this vulnerability relies on the specific implementation details of the mintToken function where the contract owner can call the function with malicious parameters that cause integer overflow conditions. When the function processes token minting operations, it fails to validate that the resulting balance values remain within acceptable numerical limits. This creates a scenario where the arithmetic operation wraps around to extremely large or negative values, effectively allowing the owner to set any user's balance to an arbitrary amount. The vulnerability is particularly dangerous because it operates at the core of the token's distribution mechanism, giving the owner unprecedented control over the token supply and user account balances.
The operational impact of this vulnerability extends beyond simple financial manipulation to encompass potential systemic risks within the Ethereum ecosystem. An attacker with access to the contract owner account can effectively drain or inflate token balances across the network, potentially causing market manipulation or complete loss of user funds. This vulnerability directly impacts the trust model of the decentralized application, as users cannot rely on the integrity of their token balances. The implications are especially severe in cryptocurrency contexts where smart contracts govern asset ownership and transfer mechanisms, as this flaw creates a pathway for unauthorized wealth redistribution and contract manipulation that could affect the entire token economy.
Mitigation strategies for this vulnerability require immediate implementation of comprehensive input validation and integer overflow protection mechanisms within the smart contract code. The recommended approach involves adding explicit bounds checking and using safe arithmetic operations that prevent overflow conditions from occurring. Developers should implement proper overflow detection using modern Solidity features such as require statements with bounds checking or employ libraries like OpenZeppelin's SafeMath that provide overflow protection. Additionally, contract owners should conduct thorough code audits and implement proper access controls to prevent unauthorized modifications to critical functions. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and represents a common pattern in smart contract development that violates the fundamental principles of secure blockchain programming and could be categorized under ATT&CK technique T1499 for data manipulation. The fix requires complete reevaluation of all arithmetic operations within the mintToken function and related token management functions to ensure proper handling of edge cases and boundary conditions.