CVE-2018-13526 in WangWangToken
Summary
by MITRE
The mintToken function of a smart contract implementation for WangWangToken, 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 • 02/27/2020
The vulnerability identified as CVE-2018-13526 represents a critical integer overflow flaw within the mintToken function of the WangWangToken smart contract deployed on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic overflow handling within the contract's code implementation, creating a fundamental security weakness that directly impacts the token's integrity and user fund safety. The flaw allows the contract owner to manipulate user balances arbitrarily, effectively enabling unauthorized fund manipulation and potential financial loss for token holders.
The technical nature of this vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations. In the context of Ethereum smart contracts, this issue manifests when the mintToken function processes token creation requests without proper bounds checking on the amount parameter. When the contract attempts to increment a user's balance by a large value that exceeds the maximum limit of the integer data type, the arithmetic operation wraps around, creating an unexpected state where the balance can be set to any arbitrary value determined by the overflow behavior. This mathematical property of integer arithmetic in programming languages allows the malicious actor to control the final balance value through careful manipulation of input parameters.
The operational impact of this vulnerability extends beyond simple balance manipulation to encompass potential systemic risks within the token ecosystem. An attacker with owner privileges can create unlimited tokens for themselves while simultaneously setting other users' balances to zero or other predetermined values, effectively enabling theft of funds and disruption of the token's economic model. The vulnerability creates a persistent risk that remains active until the contract is upgraded or replaced, as the integer overflow condition exists in the core token creation logic. This type of flaw directly violates the principle of least privilege and undermines the trust model that blockchain-based tokens rely upon for secure financial transactions.
Mitigation strategies for this vulnerability should prioritize immediate contract upgrades that implement proper integer overflow protections through explicit bounds checking and validation mechanisms. The recommended approach involves incorporating safe arithmetic operations using libraries such as OpenZeppelin's SafeMath or similar implementations that prevent overflow conditions through built-in overflow detection. Additionally, contract owners should implement comprehensive access control measures and consider multi-signature wallets for critical operations to reduce the attack surface. The vulnerability also highlights the importance of thorough smart contract auditing and adherence to security best practices such as those outlined in the OpenZeppelin security guidelines. Organizations should implement continuous monitoring systems to detect anomalous balance changes and establish incident response procedures to address potential exploitation of such vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to TA0001 (Initial Access) and TA0002 (Execution) phases, as it provides a method for attackers to gain unauthorized control over token balances and execute malicious operations within the contract's operational environment.