CVE-2018-13232 in ENTER
Summary
by MITRE
The sell function of a smart contract implementation for ENTER (ENTR) (Contract Name: EnterCoin), 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-2018-13232 resides within the sell function of the EnterCoin smart contract implementation on the Ethereum blockchain, representing a critical integer overflow flaw that directly impacts token value and user asset management. This vulnerability specifically affects the ENTRO token contract where the sell function processes transactions to convert token holdings back to ether. The flaw manifests when the mathematical operation "amount * sellPrice" results in zero due to integer overflow conditions, effectively nullifying the intended transaction value and causing significant financial loss to token holders. The vulnerability stems from improper input validation and arithmetic overflow handling within the contract's core logic, where the multiplication operation fails to account for potential overflow conditions that could occur with large numeric values. This issue directly violates the principle of secure smart contract development as outlined in the CWE-190 category for integer overflow/underflow, where operations on signed or unsigned integers exceed their maximum or minimum representable values. The operational impact of this vulnerability extends beyond simple transaction failure, as it fundamentally undermines the economic model of the token by allowing sellers to lose their assets entirely when the multiplication operation results in a zero value, effectively making the sell function unusable for certain transaction amounts. Attackers could exploit this vulnerability by manipulating transaction parameters to trigger the integer overflow condition, potentially leading to unauthorized asset depletion and loss of confidence in the token's integrity. The vulnerability's presence in a widely used token implementation demonstrates how seemingly minor arithmetic flaws in smart contracts can have substantial financial consequences, as the contract's sell function becomes unreliable for transactions involving specific amounts that trigger the overflow condition. This flaw also aligns with ATT&CK technique T1588.002 for obtaining capabilities, where adversaries exploit smart contract vulnerabilities to manipulate asset values. The security implications are compounded by the fact that Ethereum smart contracts execute with immutable code, meaning once deployed, such vulnerabilities cannot be patched without creating a new contract instance. The integer overflow condition in the sell function creates a scenario where legitimate transactions may fail or produce unintended results, undermining the trust and reliability of the token ecosystem. The vulnerability's exploitation requires understanding of Ethereum's gas mechanics and the specific arithmetic constraints of the contract's implementation, making it particularly dangerous for users who may not fully comprehend the underlying technical details of their token transactions. This flaw represents a fundamental breakdown in the contract's mathematical integrity, where the expected behavior of asset conversion fails catastrophically when the multiplication operation produces an unexpected zero result. The lack of proper overflow checks and validation mechanisms within the sell function demonstrates a critical gap in the smart contract development lifecycle, as such vulnerabilities are typically caught during thorough code review and formal verification processes. The vulnerability's persistence in the Ethereum blockchain environment means that affected users may experience permanent loss of funds or assets, as the contract's behavior cannot be corrected through simple code updates. This issue highlights the importance of implementing comprehensive testing strategies including formal verification, symbolic execution, and thorough edge case analysis before deploying smart contracts to production environments. The integer overflow in the sell function creates a cascading effect that could potentially impact other contract functions that depend on the proper functioning of the sell operation, further amplifying the security implications of this vulnerability. The vulnerability's classification as a critical issue underscores the need for robust security frameworks and continuous monitoring of smart contract implementations to prevent similar flaws from compromising user assets and blockchain ecosystems. The presence of such vulnerabilities in token contracts demonstrates the urgent need for industry-wide adoption of secure coding practices and comprehensive security auditing procedures for all smart contract deployments.