CVE-2018-13624 in WXSLToken
Summary
by MITRE
The mintToken function of a smart contract implementation for WXSLToken, 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 • 02/28/2020
The vulnerability identified in CVE-2018-13624 represents a critical integer overflow flaw within the mintToken function of the WXSLToken smart contract implementation on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types. The flaw allows the contract owner to manipulate token balances by setting arbitrary values for user accounts, fundamentally compromising the integrity of the token economy. The issue manifests when the mintToken function processes token minting operations without proper overflow checks, enabling attackers to exploit the mathematical limitations of fixed-size integer representations. The vulnerability directly impacts the security model of the token by undermining the fundamental principle of controlled token distribution and user balance management that is essential for blockchain-based financial systems.
The technical implementation of this vulnerability follows a classic integer overflow pattern where arithmetic operations in the mintToken function exceed the maximum value that can be represented by the underlying integer type. This allows the contract owner to manipulate the token supply and user balances through carefully crafted inputs that cause the arithmetic to wrap around to unexpected values. The vulnerability is particularly dangerous because it operates within the privileged owner account context, giving the attacker direct control over the contract's state management functions. The flaw can be exploited to either inflate user balances beyond intended limits or to manipulate account balances to zero, effectively creating a mechanism for unauthorized fund manipulation. This type of vulnerability is categorized under CWE-190 as an integer overflow or wraparound, which represents a well-documented class of vulnerabilities in both traditional software and blockchain smart contracts. The exploitability of this vulnerability is further enhanced by the lack of proper access controls and input validation mechanisms within the mintToken function.
The operational impact of CVE-2018-13624 extends beyond simple balance manipulation to potentially compromise the entire token ecosystem and user trust in the platform. When exploited, this vulnerability can result in unauthorized token creation, leading to inflation of the token supply and devaluation of existing holdings. The ability to set arbitrary balances also enables the contract owner to manipulate trading dynamics, potentially creating artificial market conditions that benefit the attacker while harming legitimate users. This vulnerability undermines the core security assumptions of the token contract and can lead to significant financial losses for token holders who rely on the integrity of the smart contract for their asset management. The impact is particularly severe in decentralized finance applications where such vulnerabilities can be exploited to drain funds or manipulate market prices. From an ATT&CK framework perspective, this vulnerability aligns with techniques related to privilege escalation and resource hijacking, allowing the attacker to gain unauthorized control over contract resources and user assets. The vulnerability also represents a failure in the security testing and auditing processes that should have identified such fundamental flaws in the contract's arithmetic operations.
Mitigation strategies for CVE-2018-13624 require immediate implementation of proper integer overflow protections within the smart contract code. The most effective approach involves implementing comprehensive input validation and using safe arithmetic operations that check for overflow conditions before performing calculations. Contract developers should employ libraries such as OpenZeppelin's SafeMath or similar arithmetic libraries that automatically handle overflow protection in all mathematical operations. The mintToken function must be redesigned to include explicit checks for maximum integer limits and proper boundary validation before any balance modifications occur. Additionally, implementing proper access controls and multi-signature requirements for owner functions can reduce the risk of unauthorized exploitation. Regular security audits and formal verification processes should be established to identify similar vulnerabilities before deployment. The contract should also implement comprehensive logging and monitoring of all token minting operations to detect suspicious activities. From a defensive standpoint, users should avoid interacting with contracts that have not been properly audited and validated for such vulnerabilities. The remediation process must include thorough testing of all arithmetic operations and comprehensive security reviews that specifically target integer overflow conditions and other common smart contract vulnerabilities. Organizations should also consider implementing automated testing frameworks that can identify these types of issues during development cycles.