CVE-2018-13167 in Yu Gi Oh
Summary
by MITRE
The mintToken function of a smart contract implementation for Yu Gi Oh (YGO), 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 as CVE-2018-13167 resides within the mintToken function of a smart contract implementation for the Yu Gi Oh (YGO) Ethereum token. This flaw represents a critical integer overflow vulnerability that fundamentally compromises the contract's integrity and security model. The vulnerability stems from improper input validation and arithmetic handling within the token minting mechanism, creating a scenario where the contract owner can manipulate user balances arbitrarily. Such a flaw directly violates the fundamental principles of blockchain security and asset management, as it allows for unauthorized balance manipulation that can result in significant financial losses and contract integrity breaches.
The technical implementation of this vulnerability manifests through the mintToken function's failure to properly validate or constrain integer values during balance calculations. When the contract owner invokes this function, they can specify arbitrary values for token minting operations, which then get directly assigned to user balances without proper overflow checks. This creates an environment where the integer overflow occurs during the arithmetic operations, allowing the attacker to manipulate the token supply and user balances beyond normal operational parameters. The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses situations where integer arithmetic operations produce results that exceed the maximum value representable by the data type. The impact is particularly severe because it allows for privilege escalation through the contract owner account, enabling unauthorized balance manipulation that can be exploited to drain funds or create artificial wealth within the token ecosystem.
The operational impact of this vulnerability extends far beyond simple balance manipulation, as it fundamentally undermines trust in the token's value system and the underlying smart contract. An attacker with owner privileges can increase any user's balance to arbitrary values, potentially leading to massive inflation of the token supply and complete devaluation of the asset. This vulnerability also creates opportunities for gaming the token economy, where malicious actors could artificially inflate their own balances while simultaneously reducing others' holdings. The attack vector is particularly concerning because it requires only owner-level privileges, which are typically limited to a small number of trusted parties, making the vulnerability more exploitable in practice. This flaw can be categorized under the ATT&CK technique T1059.001 Command and Scripting Interpreter, as the vulnerability enables the execution of malicious commands through the manipulation of token balances and supply parameters.
Mitigation strategies for this vulnerability must address both the immediate technical flaw and the broader security implications for smart contract implementations. The primary solution involves implementing comprehensive input validation and integer overflow protection mechanisms within the mintToken function, ensuring that all arithmetic operations include proper bounds checking and validation. Smart contract developers should employ established security patterns such as the SafeMath library or similar arithmetic protection mechanisms that prevent overflow conditions. Additionally, the contract should implement proper access controls and audit logging to track all minting operations and balance modifications. Regular security audits and formal verification processes should be conducted to identify similar vulnerabilities in other functions and prevent future occurrences. The vulnerability also highlights the importance of implementing proper privilege separation and multi-signature requirements for critical contract operations, reducing the risk associated with single points of failure in smart contract ownership. Organizations should also consider implementing automated monitoring systems that can detect unusual balance changes or minting activities that may indicate exploitation attempts.