CVE-2018-13688 in MallToken
Summary
by MITRE
The mintToken function of a smart contract implementation for MallToken, 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 CVE-2018-13688 vulnerability represents a critical integer overflow flaw within the mintToken function of the MallToken smart contract deployed on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types. The flaw allows the contract owner to manipulate token balances by setting arbitrary values for any user account, effectively creating unlimited tokens or manipulating existing balances in ways that were never intended by the contract design.
The technical nature of this vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions where an integer value exceeds the maximum representable value for its data type. In the context of Ethereum smart contracts, this typically occurs when developers fail to implement proper bounds checking before performing arithmetic operations such as addition or multiplication on uint256 or similar unsigned integer types. The mintToken function likely performs operations without verifying that the resulting values remain within valid integer ranges, creating a path for malicious manipulation by the contract owner.
The operational impact of this vulnerability extends beyond simple financial manipulation to potentially compromise the entire token ecosystem. An attacker with owner privileges can artificially inflate token balances for specific accounts, manipulate total supply calculations, or create situations where the contract's mathematical integrity is compromised. This could lead to immediate financial losses for token holders, undermine trust in the token's value, and potentially cause the contract to behave unpredictably when performing subsequent operations that depend on accurate balance calculations. The vulnerability particularly affects token governance models where the owner has elevated privileges and can directly modify user balances without proper authorization mechanisms.
Mitigation strategies for CVE-2018-13688 should focus on implementing comprehensive input validation and arithmetic safety checks within the smart contract code. Developers must ensure that all arithmetic operations include proper overflow and underflow protections, typically achieved through the use of libraries such as OpenZeppelin's SafeMath or similar mathematical operation wrappers that automatically check for overflow conditions. The contract should also implement proper access controls and audit trails to track balance modifications, while the owner privileges should be carefully restricted to prevent arbitrary balance manipulations. Additionally, regular smart contract security audits and formal verification techniques should be employed to identify similar vulnerabilities before deployment. This vulnerability demonstrates the importance of adhering to established security frameworks and standards, including those outlined in the OWASP Smart Contract Security Verification Standard, to prevent attackers from exploiting fundamental mathematical flaws in blockchain applications.