CVE-2018-13231 in ENTER
Summary
by MITRE
The sell function of a smart contract implementation for ENTER (ENTR) (Contract Name: EnterToken), 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 as CVE-2018-13231 resides within the EnterToken smart contract implementation on the Ethereum blockchain, specifically affecting the sell function of the ENTER (ENTR) token. This issue represents a classic integer overflow condition that fundamentally compromises the contract's financial integrity and user asset management capabilities. The flaw manifests when the sell function processes transactions where the multiplication operation between amount and sellPrice results in an overflow condition that evaluates to zero, thereby enabling malicious actors to manipulate their asset positions within the contract.
The technical implementation of this vulnerability stems from improper input validation and arithmetic overflow handling within the smart contract's sell function. When a user attempts to sell tokens, the contract calculates the proceeds by multiplying the token amount with the current sellPrice. However, the contract fails to properly validate that this multiplication operation will not exceed the maximum representable value for the data type being used, typically a 256-bit unsigned integer in Ethereum's Solidity environment. This oversight allows for scenarios where legitimate mathematical operations result in unexpected zero values, effectively nullifying the intended transaction outcomes and enabling unauthorized asset manipulation.
The operational impact of this vulnerability extends beyond simple financial loss, as it creates a fundamental weakness in the token's economic model and user trust within the system. Users who attempt to sell their tokens may find their transaction amounts reduced to zero due to the overflow condition, resulting in complete loss of value for their holdings. This vulnerability particularly affects the contract's ability to maintain accurate accounting of user balances and transaction histories, potentially enabling sophisticated attack vectors where malicious actors systematically exploit the overflow to drain assets from the contract or manipulate market prices through coordinated selling activities.
From a cybersecurity perspective, this vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses conditions where arithmetic operations exceed the maximum value that can be represented by the data type. The issue also maps to ATT&CK technique T1059.001, Command and Scripting Interpreter, as it enables attackers to craft specific transaction patterns that exploit the mathematical overflow for unauthorized gain. The vulnerability demonstrates a critical gap in smart contract security practices, particularly in the absence of proper overflow checks and input validation mechanisms that are standard requirements in secure software development methodologies.
Mitigation strategies for this vulnerability require immediate implementation of comprehensive input validation and arithmetic overflow protection within the smart contract code. Developers must implement explicit checks to ensure that multiplication operations do not exceed safe integer limits, utilizing libraries such as OpenZeppelin's SafeMath or similar arithmetic protection mechanisms. Additionally, thorough code auditing and formal verification processes should be employed to identify similar vulnerabilities across the entire smart contract ecosystem. The contract should also implement proper logging and monitoring capabilities to detect anomalous transaction patterns that might indicate exploitation attempts, while establishing clear boundaries for acceptable transaction values and implementing robust error handling that prevents zero-value transactions from being processed.