CVE-2018-13615 in MJCToken
Summary
by MITRE
The mintToken function of a smart contract implementation for MJCToken, 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-2018-13615 represents a critical integer overflow flaw within the mintToken function of the MJCToken smart contract implementation on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic handling within the contract's code, specifically affecting the token's minting mechanism that allows contract owners to create new tokens. The flaw manifests when the contract attempts to perform arithmetic operations on token balances without proper overflow checks, creating a scenario where malicious actors can manipulate the token supply and user balances through carefully crafted transactions. The integer overflow vulnerability directly maps to CWE-190, which classifies integer overflow and underflow conditions, and can be leveraged to exploit the contract's core functionality in ways that compromise the integrity of the token ecosystem. The vulnerability exists within the Ethereum smart contract execution environment where all operations occur on the blockchain and are immutable once executed, making such flaws particularly dangerous as they can be exploited without detection until the malicious actions are completed. The operational impact of this vulnerability extends beyond simple balance manipulation, as it enables contract owners to potentially drain token supplies, create artificial scarcity, or manipulate token distributions in ways that undermine the trust and value proposition of the MJCToken.
The technical exploitation of this vulnerability requires a deep understanding of Ethereum smart contract mechanics and the specific implementation details of the mintToken function. Attackers can leverage the integer overflow to cause unexpected behavior when adding token amounts to user balances, potentially allowing them to set any user's balance to an arbitrary value including extremely large numbers or even zero. This occurs because the contract fails to implement proper bounds checking or overflow protection mechanisms that are standard in secure smart contract development practices. The vulnerability is particularly concerning as it affects the fundamental tokenomics of the MJCToken system, enabling unauthorized manipulation of the token distribution and potentially allowing attackers to mint unlimited tokens or manipulate user balances to gain unfair advantages within the token economy. The exploitability of this vulnerability is high as it requires no special privileges beyond those already granted to the contract owner, and the effects are immediately visible on the blockchain, making it a prime target for malicious actors seeking to manipulate token values. The flaw also aligns with ATT&CK technique T1059.006 for smart contract manipulation, where adversaries exploit weaknesses in contract logic to achieve unauthorized outcomes.
Mitigation strategies for CVE-2018-13615 must address the root cause through comprehensive code auditing and secure development practices. The most effective remediation involves implementing proper integer overflow protection mechanisms such as using safe math libraries, implementing explicit bounds checking, and employing require statements to validate input parameters before executing arithmetic operations. Contract developers should utilize established frameworks like OpenZeppelin's SafeMath library that provides overflow-checked arithmetic operations to prevent such vulnerabilities from manifesting in production code. The solution also requires thorough testing of all arithmetic operations within smart contracts, including edge cases that could trigger overflow conditions, and comprehensive code reviews that specifically examine all mathematical operations for proper boundary handling. Additionally, implementing proper access controls and audit mechanisms can help detect unauthorized attempts to exploit the vulnerability, while regular security audits and penetration testing should be conducted to identify similar flaws in other contract functions. Organizations should also consider implementing multi-signature wallets and time locks for critical contract operations to add additional layers of security beyond the basic ownership controls that might be exploited through this vulnerability. The remediation process must also include updating all related contracts and ensuring that the fix is deployed across the entire token ecosystem to prevent attackers from exploiting the vulnerability in any part of the distributed system.