CVE-2018-13075 in Carbon Exchange Coin Token
Summary
by MITRE
The mintToken function of a smart contract implementation for Carbon Exchange Coin Token (CEC), 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 • 02/24/2020
The vulnerability identified as CVE-2018-13075 affects the Carbon Exchange Coin Token (CEC) smart contract deployed on the Ethereum blockchain, representing a critical integer overflow flaw within the mintToken function. This vulnerability stems from inadequate input validation and arithmetic overflow handling in the contract's code implementation, creating a pathway for unauthorized manipulation of token balances. The flaw specifically manifests when the mintToken function processes token minting operations without proper bounds checking, allowing an attacker with owner privileges to manipulate the token supply and user balances beyond normal operational parameters.
The technical exploitation of this vulnerability occurs through the manipulation of integer arithmetic operations within the mintToken function, where the contract fails to validate that the resulting token balance would not exceed the maximum value representable by the underlying data type. This creates an overflow condition that can be leveraged to set arbitrary user balances to predetermined values, effectively allowing the contract owner to manipulate the token distribution and potentially drain or manipulate the token economy. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, specifically manifesting as an unsigned integer overflow that can be exploited to achieve unintended program behavior.
Operationally, this vulnerability presents significant risks to the integrity of the Carbon Exchange Coin Token ecosystem, as it allows the contract owner to manipulate user balances without detection. The impact extends beyond simple balance manipulation to potentially compromise the entire token economy, as attackers could inflate their own balances or reduce others' balances to zero, effectively creating a mechanism for unauthorized wealth transfer. The vulnerability's severity is amplified by the fact that it requires no external interaction beyond the owner's privileges, making it particularly dangerous for token contracts where the owner has elevated control over the system's operations. This flaw directly impacts the principle of least privilege and can be categorized under ATT&CK technique T1068 as an exploitation of local privilege escalation.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protections within the smart contract code, including the use of SafeMath libraries or similar arithmetic validation mechanisms that prevent overflow conditions. The contract owner should implement comprehensive input validation for all parameters passed to the mintToken function, ensuring that balance calculations remain within acceptable bounds. Additionally, regular security audits and formal verification of smart contract code should be conducted to identify similar vulnerabilities before they can be exploited. The implementation of access control mechanisms and multi-signature requirements for critical operations can also reduce the risk associated with owner privileges being compromised. Organizations should also consider implementing monitoring systems that track unusual balance changes or minting operations to detect potential exploitation attempts. The vulnerability highlights the importance of adhering to secure coding practices in blockchain environments where financial assets are at risk and demonstrates how seemingly simple arithmetic operations can lead to catastrophic security failures.