CVE-2018-13643 in GCRTokenERC20
Summary
by MITRE
The mintToken function of a smart contract implementation for GCRTokenERC20, 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-2018-13643 represents a critical integer overflow flaw within the mintToken function of the GCRTokenERC20 smart contract implementation on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic overflow handling within the contract's token minting mechanism, creating a significant security risk for the token ecosystem. The flaw allows the contract owner to manipulate user balances arbitrarily, fundamentally compromising the integrity of the token's accounting system and potentially enabling unauthorized wealth transfer operations.
The technical nature of this vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which occurs when an arithmetic operation produces a result that exceeds the maximum value that can be represented by the underlying data type. In the context of Ethereum smart contracts, this typically manifests when operations on uint256 variables exceed their maximum value of 2^256 - 1, causing the value to wrap around to zero or a negative number depending on the implementation. The mintToken function specifically fails to validate that the minting operation will not cause an overflow condition, allowing an attacker with owner privileges to craft malicious inputs that result in unexpected balance states.
The operational impact of this vulnerability extends beyond simple balance manipulation and represents a fundamental breach of trust in the token's governance model. An attacker with owner access can effectively create unlimited tokens or manipulate existing token balances to any desired value, potentially enabling them to drain funds from other users or create artificial wealth distribution. This vulnerability directly violates the core principles of blockchain security and token economics, as it undermines the immutability and fairness of the token distribution mechanism. The implications are particularly severe given that the contract owner maintains control over the minting process, creating a potential attack vector for financial loss and system compromise.
Mitigation strategies for this vulnerability must address both the immediate code-level fixes and broader governance considerations. The primary technical solution involves implementing proper overflow checks using modern solidity practices such as the SafeMath library or compiler versions that enable automatic overflow checking. Additionally, the mintToken function should validate input parameters to ensure that balance additions do not exceed the maximum representable value. From a defensive perspective, this vulnerability highlights the importance of comprehensive smart contract auditing and adherence to security best practices as outlined in the OWASP Smart Contract Security Verification Standard. The ATT&CK framework for blockchain environments would categorize this as a privilege escalation technique where an attacker leverages existing administrative rights to manipulate core contract state, emphasizing the critical need for least-privilege principles and regular security assessments in decentralized applications.