CVE-2018-13227 in MoneyChainNet
Summary
by MITRE
The sell function of a smart contract implementation for MoneyChainNet (MCN), an Ethereum token, has an integer overflow in which "amount * sellPrice" can be zero, consequently reducing a seller's assets.
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Analysis
by VulDB Data Team • 02/25/2020
The vulnerability identified in CVE-2018-13227 affects the MoneyChainNet (MCN) smart contract implementation on the Ethereum blockchain, specifically targeting the sell function within the token contract's logic. This represents a critical security flaw that directly impacts the financial integrity of the token economy and the trustworthiness of the underlying smart contract infrastructure. The vulnerability manifests as an integer overflow condition that occurs during the calculation process when determining the value of tokens being sold, creating a scenario where mathematical operations can produce incorrect results due to the limitations of fixed-size integer representations in the Ethereum Virtual Machine.
The technical flaw stems from the improper handling of arithmetic operations within the sell function where the multiplication of "amount * sellPrice" can result in zero values under certain conditions. This occurs because the smart contract does not adequately validate or sanitize the input parameters before performing mathematical operations, allowing for scenarios where the calculated value becomes truncated or wrapped around to zero due to integer overflow behavior. The vulnerability is classified as a CWE-191 Integer Underflow/Overflow, which represents a fundamental weakness in the implementation that directly leads to incorrect program behavior and potential financial loss for users. When the multiplication operation exceeds the maximum value that can be represented by the integer data type, the result wraps around to zero, effectively nullifying the transaction value and causing the seller to lose assets.
The operational impact of this vulnerability extends beyond simple mathematical errors to encompass significant financial risks for token holders and the broader ecosystem. Users who attempt to sell their MCN tokens may find that their transactions result in zero value returns, effectively transferring their assets without compensation, which undermines the fundamental utility and value proposition of the token. This vulnerability creates an attack surface that could be exploited by malicious actors to drain user funds systematically, potentially leading to complete loss of value within the token economy. The issue particularly affects the contract's ability to maintain accurate accounting of token balances and transaction values, creating inconsistencies in the distributed ledger that could compromise the integrity of the entire blockchain-based financial system. The vulnerability also impacts the contract's ability to enforce proper tokenomics and pricing mechanisms, as the sell function's mathematical foundation becomes unreliable.
Mitigation strategies for this vulnerability must address both the immediate code-level fixes and broader architectural considerations for smart contract security. The primary remediation involves implementing proper input validation and boundary checking before any arithmetic operations, ensuring that the multiplication of amount and sellPrice cannot result in zero values through overflow conditions. This requires the addition of explicit checks to validate that the calculated value remains within expected ranges and implementing safe math libraries that handle integer operations with overflow protection. Organizations should also consider implementing proper error handling mechanisms that can detect and prevent invalid transactions from being processed, along with comprehensive testing procedures that include edge case scenarios for mathematical operations. The vulnerability highlights the importance of following established security standards and best practices for smart contract development, including adherence to the principles outlined in the OpenZeppelin security guidelines and the need for thorough code reviews and formal verification processes. Additionally, implementing proper access controls and transaction monitoring systems can help detect anomalous behavior patterns that may indicate exploitation attempts, while regular security audits should be conducted to identify similar vulnerabilities across the entire smart contract ecosystem.