CVE-2018-13745 in STCToken
Summary
by MITRE
The mintToken function of a smart contract implementation for STCToken, 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 as CVE-2018-13745 represents a critical integer overflow flaw within the mintToken function of STCToken smart contract implementations on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic overflow handling within the contract's code, creating a scenario where the contract owner can manipulate user balances arbitrarily. The flaw manifests when the mintToken function processes token minting operations without proper bounds checking, allowing for overflow conditions that can be exploited to manipulate account balances. Such vulnerabilities are particularly dangerous in decentralized applications where trustless execution is expected, as they fundamentally undermine the integrity of the tokenomics and user account management systems.
The technical implementation of this vulnerability can be categorized under CWE-190, Integer Overflow or Wraparound, which occurs when an integer operation exceeds the maximum value that can be represented by the underlying data type. In Ethereum smart contracts, this typically manifests when arithmetic operations are performed without proper overflow protection mechanisms, especially when dealing with uint256 data types that can overflow when reaching their maximum value of 2^256 - 1. The mintToken function specifically fails to validate the resulting balance after minting operations, allowing attackers to craft inputs that cause the arithmetic to wrap around and produce unintended balance values. This vulnerability directly violates the fundamental principles of secure smart contract development as outlined in the Ethereum Smart Contract Security Best Practices and can be mapped to ATT&CK technique T1499.004, which covers the exploitation of vulnerabilities in smart contracts to manipulate system state.
The operational impact of CVE-2018-13745 extends beyond simple balance manipulation, potentially enabling contract owners to drain funds from user accounts or create artificial wealth distributions that could be exploited for financial gain. Attackers can leverage this vulnerability to set user balances to extremely large values, effectively creating infinite supply conditions or manipulating token distributions in ways that could destabilize the entire token economy. The implications are particularly severe given that token contracts often handle significant financial value and user assets, making this vulnerability a prime target for exploitation in the decentralized finance ecosystem. The vulnerability also poses risks to the broader Ethereum ecosystem as it demonstrates the potential for widespread impact when fundamental security principles are not properly implemented, potentially affecting user trust in smart contract applications and leading to significant financial losses.
Mitigation strategies for this vulnerability require immediate implementation of proper overflow protection mechanisms throughout the smart contract codebase, particularly in functions that handle arithmetic operations and balance modifications. The recommended approach involves utilizing safe math libraries such as OpenZeppelin's SafeMath or implementing explicit overflow checks before any arithmetic operations that could potentially exceed data type limits. Contract developers should also implement proper access controls and input validation to prevent unauthorized manipulation of critical functions. Additionally, regular security audits and formal verification processes should be conducted to identify and remediate similar vulnerabilities before deployment. The vulnerability highlights the importance of adhering to established security frameworks and standards, including the Ethereum Improvement Proposals that specify secure coding practices for smart contract development, ensuring that such fundamental flaws do not compromise the integrity of blockchain-based financial systems.