CVE-2018-13163 in Ethernet Cash
Summary
by MITRE
The mintToken function of a smart contract implementation for Ethernet Cash (ENC), 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 • 02/25/2020
The vulnerability identified in CVE-2018-13163 affects the Ethereum-based token implementation known as Ethernet Cash (ENC) where a critical integer overflow exists within the mintToken function. This flaw represents a fundamental security weakness in the smart contract's arithmetic operations that directly impacts the token's integrity and user fund security. The vulnerability stems from improper input validation and arithmetic handling within the contract's codebase, creating an exploitable condition that allows unauthorized manipulation of user balances.
The technical implementation of this vulnerability resides in the mintToken function where integer overflow occurs during balance calculations. When the contract attempts to increment user balances through the minting process, the arithmetic operations fail to properly validate input values against the maximum limits of the integer data types used. This allows an attacker with contract ownership privileges to manipulate the mintToken function parameters to create overflow conditions that result in arbitrary balance manipulation. The flaw aligns with CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations, making it a classic example of improper integer handling in smart contracts.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token economy and user trust. An attacker with ownership access can set any user's balance to arbitrary values including extremely high amounts or negative balances, effectively allowing for unlimited token creation and distribution. This creates a severe financial risk for token holders and can lead to immediate loss of value in the token ecosystem. The vulnerability also undermines the fundamental principles of blockchain token economics where transparency and immutability are expected. From an attacker's perspective, this represents a high-value target within the ATT&CK framework under the privilege escalation category, as it allows for unauthorized control over user assets and contract state manipulation.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and arithmetic boundary checks within the smart contract code. Developers must ensure that all integer operations include overflow and underflow protection mechanisms, typically through the use of require statements or dedicated overflow protection libraries. The contract should validate all input parameters to the mintToken function against maximum value limits before performing any arithmetic operations. Additionally, comprehensive code auditing and formal verification processes should be implemented to identify similar patterns across the entire smart contract codebase. Regular security assessments and peer reviews of smart contract implementations are essential to prevent such vulnerabilities from being introduced in future deployments, as the vulnerability demonstrates the critical importance of proper integer handling in blockchain applications and the potential for severe financial consequences when such protections are absent.