CVE-2018-13550 in Coquinho Coin
Summary
by MITRE
The mintToken function of a smart contract implementation for Coquinho Coin (CQNC) (Contract Name: CoquinhoERC20), 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 • 02/27/2020
The vulnerability identified in CVE-2018-13550 represents a critical integer overflow flaw within the mintToken function of the Coquinho Coin (CQNC) smart contract implementation. This vulnerability specifically affects the Ethereum-based token contract known as CoquinhoERC20 and stems from improper input validation and arithmetic handling within the token minting mechanism. The flaw allows the contract owner to manipulate user balances beyond normal operational parameters, creating a fundamental security breach that undermines the integrity of the token economy. The vulnerability manifests when the mintToken function processes token creation requests without adequate overflow checks, enabling malicious or unauthorized balance manipulation through carefully crafted inputs.
The technical implementation of this vulnerability aligns with CWE-191, which describes integer underflow/overflow conditions in software systems. In the context of Ethereum smart contracts, this represents a classic example of insufficient input validation where the contract fails to properly validate the parameters passed to the mintToken function. The flaw occurs when arithmetic operations exceed the maximum value that can be represented by the data type being used, causing the value to wrap around to an unexpected result. This particular implementation likely uses unsigned integer types that can overflow when incremented beyond their maximum capacity, allowing an attacker to manipulate the balance calculation in a predictable manner. The contract owner can exploit this by providing carefully calculated values that cause the overflow to result in the desired target balance, effectively bypassing normal token distribution controls.
The operational impact of this vulnerability extends far beyond simple balance manipulation, creating a comprehensive threat to the token ecosystem and user funds. An attacker with access to the contract owner privileges can arbitrarily set any user's balance to any desired amount, potentially leading to massive inflation of the token supply or unauthorized access to funds. This vulnerability directly enables scenarios where malicious actors could create unlimited balances for themselves or other users, effectively undermining the entire token economic model. The implications include potential loss of user funds, complete compromise of the token's value proposition, and significant damage to the trust in the underlying blockchain infrastructure. The vulnerability also creates opportunities for financial manipulation and could be exploited to perform sophisticated attacks such as reentrancy exploits or other advanced smart contract vulnerabilities that compound the initial overflow issue.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security enhancements. The primary fix involves implementing comprehensive input validation and overflow protection mechanisms within the mintToken function, utilizing safe arithmetic operations that prevent integer overflows through proper boundary checks and validation. Developers should employ established security patterns such as the SafeMath library or similar arithmetic libraries that provide overflow protection for all mathematical operations within smart contracts. The implementation must include proper parameter validation to ensure that token minting operations cannot result in values that exceed the maximum representable integer limits. Additionally, access controls should be strengthened to ensure that only authorized parties can execute mintToken operations, and the contract should implement comprehensive logging and monitoring capabilities to detect unauthorized balance manipulations. Organizations should also consider implementing formal verification techniques and thorough code audits to identify similar vulnerabilities across their entire smart contract portfolio, as this type of vulnerability often indicates broader security implementation gaps that may affect other contract functions. The vulnerability demonstrates the critical importance of adhering to established security frameworks and best practices in smart contract development, including the principles outlined in the OWASP Smart Contract Security Verification Standard and other industry-recognized security guidelines.