CVE-2018-13477 in CTESale
Summary
by MITRE
The mintToken function of a smart contract implementation for CTESale, 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 • 02/26/2020
The vulnerability identified in CVE-2018-13477 represents a critical integer overflow flaw within the mintToken function of the CTESale Ethereum token smart contract implementation. This vulnerability stems from inadequate input validation and arithmetic operation handling within the smart contract code, creating a scenario where the contract owner can manipulate user balances arbitrarily. The flaw manifests when the mintToken function processes token minting operations without proper overflow checks, allowing malicious or unauthorized actions by the contract owner. The vulnerability is particularly concerning because it directly impacts the fundamental integrity of the token economy by enabling the manipulation of user balances and potentially affecting the total supply calculations.
The technical implementation of this vulnerability falls under CWE-190, which specifically addresses integer overflow and underflow conditions. In Ethereum smart contracts, such vulnerabilities occur when arithmetic operations exceed the maximum value that can be stored in the data type being used, causing the value to wrap around to zero or negative numbers. The mintToken function likely performs operations that do not properly validate whether the resulting balance would exceed the maximum value allowed for the data type, typically a 256-bit unsigned integer in Ethereum. This allows an attacker with contract owner privileges to execute calculations that result in overflow conditions, enabling them to set arbitrary user balances through carefully crafted inputs that exploit the mathematical properties of the underlying data types.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token ecosystem and user trust. When a contract owner can set any user's balance to any arbitrary value, they effectively gain control over token distribution and can manipulate market dynamics, potentially leading to significant financial losses for other token holders. The vulnerability also affects the contract's total supply calculations, as the overflow conditions can result in incorrect tracking of the actual token supply. This creates a scenario where the smart contract's state becomes inconsistent with the expected token economics, potentially enabling further exploits or making the contract fundamentally unreliable for its intended use case. The vulnerability is particularly dangerous because it can be exploited without requiring external user interaction, as the contract owner already possesses the necessary privileges to execute the malicious mintToken function.
Mitigation strategies for CVE-2018-13477 require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. The recommended approach involves incorporating comprehensive input validation and overflow checks before any arithmetic operations are performed in the mintToken function. This includes implementing bounded arithmetic operations that explicitly check for overflow conditions using techniques such as the SafeMath library or similar mathematical libraries that prevent overflows through explicit checks. Additionally, contract owners should implement proper access control mechanisms to ensure that only authorized parties can execute token minting operations, and regular security audits should be conducted to identify similar vulnerabilities across the entire smart contract ecosystem. The vulnerability also highlights the importance of following secure coding practices for smart contracts, including the use of established frameworks and libraries that provide built-in protection against common mathematical errors and security flaws. Organizations should also consider implementing monitoring systems that can detect anomalous balance changes or unexpected token supply modifications that might indicate exploitation of similar vulnerabilities.