CVE-2018-13778 in CGCToken
Summary
by MITRE
The mintToken function of a smart contract implementation for CGCToken, 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 • 03/03/2020
The vulnerability identified in CVE-2018-13778 represents a critical integer overflow flaw within the mintToken function of the CGCToken smart contract deployed on the Ethereum blockchain. This vulnerability stems from inadequate input validation and overflow handling mechanisms within the contract's code implementation. The flaw allows the contract owner to manipulate token balances by setting arbitrary values for user accounts, effectively bypassing normal token minting and distribution protocols. The vulnerability specifically affects the token's total supply management and individual account balance calculations, creating a pathway for unauthorized balance manipulation that could compromise the entire token economy.
The technical root cause of this vulnerability aligns with CWE-190, which describes integer overflow and underflow conditions in software implementations. In Ethereum smart contracts, this manifests when arithmetic operations exceed the maximum value that can be stored in the designated data type, typically affecting uint256 or similar unsigned integer types. The mintToken function fails to implement proper overflow checks before performing balance updates, allowing malicious actors with owner privileges to execute calculations that wrap around to unexpected values. This creates a scenario where the owner can effectively mint unlimited tokens or set any user's balance to arbitrary amounts, fundamentally undermining the token's integrity and security model.
The operational impact of this vulnerability extends beyond simple balance manipulation to encompass potential financial losses, market manipulation opportunities, and complete compromise of the token's economic model. An attacker with owner access could inflate their own balance or set other users' balances to zero, effectively destroying the token's utility and value proposition. The vulnerability also enables potential denial of service attacks against legitimate users by setting their balances to zero or other invalid values. From a blockchain security perspective, this flaw represents a significant risk to user funds and contract integrity, as it allows for unauthorized value transfers and contract state manipulation that bypasses normal transaction validation mechanisms. The impact is particularly severe because it operates at the contract level rather than requiring external exploitation, making it accessible to anyone with owner privileges.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. The recommended approach involves utilizing safe math libraries such as OpenZeppelin's SafeMath or implementing explicit overflow checks before any arithmetic operations that modify token balances. Additionally, the contract should enforce proper access control measures to ensure that only authorized entities can execute mintToken functions, and these functions should include comprehensive input validation to prevent malicious value injection. The vulnerability also highlights the importance of thorough smart contract auditing and testing, particularly for functions that manipulate token supply or user balances, as outlined in the ATT&CK framework's smart contract security considerations. Regular security assessments and code reviews should be implemented to identify similar vulnerabilities in other contract functions, ensuring that all arithmetic operations include appropriate overflow protection mechanisms and that access controls are properly enforced throughout the contract's functionality.