CVE-2018-13781 in MyYLC
Summary
by MITRE
The mintToken function of a smart contract implementation for MyYLC, 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 • 03/03/2020
The vulnerability identified in CVE-2018-13781 represents a critical integer overflow flaw within the mintToken function of MyYLC Ethereum token smart contract implementation. This vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which occurs when a program fails to properly handle arithmetic operations that exceed the maximum value that can be represented by a given integer type. The flaw specifically affects the token contract's ability to manage user balances through the mintToken function, which is typically used to create new tokens and distribute them to users.
The technical nature of this vulnerability allows an attacker with ownership privileges of the smart contract to manipulate the balance of any user account within the token ecosystem. When the mintToken function processes token creation requests, it fails to validate whether the resulting balance would exceed the maximum representable value for the integer data type used to store balances. This overflow condition creates a scenario where an attacker can cause the balance to wrap around to an unexpectedly low value or even zero, effectively allowing manipulation of user account balances beyond normal operational parameters.
From an operational standpoint, this vulnerability presents significant security implications for the MyYLC token ecosystem and its users. The ability to set arbitrary user balances creates potential for financial manipulation, including the possibility of creating unlimited tokens or transferring funds between accounts without proper authorization. The impact extends beyond simple balance manipulation as it fundamentally undermines the integrity of the token economy and the trust users place in the smart contract system. This vulnerability directly affects the security properties of the blockchain-based token, potentially enabling unauthorized wealth redistribution and undermining the economic model of the token.
The vulnerability aligns with several ATT&CK techniques including T1059.001 for command and scripting interpreter execution through smart contract manipulation and T1496 for resource hijacking through unauthorized token creation. The attack surface is particularly concerning because it requires only the contract owner's private key, making it a high-risk issue for any token that has been deployed with owner privileges that have not been properly secured or transferred to a multisignature wallet. Mitigation strategies should include implementing proper integer overflow checks using require statements with appropriate bounds validation, utilizing safe math libraries such as OpenZeppelin's SafeMath, and ensuring that all balance modifications are properly validated against maximum representable values. Additionally, contract owners should consider implementing proper access controls and regular security audits to prevent unauthorized access to privileged functions.
The vulnerability demonstrates the critical importance of proper input validation in smart contract development and highlights the need for comprehensive security testing before deployment. Organizations implementing blockchain-based token systems must understand that vulnerabilities in core functions like mintToken can have cascading effects on the entire token economy. The remediation process should involve not only fixing the immediate overflow issue but also conducting thorough code reviews to identify similar patterns throughout the smart contract codebase. This particular vulnerability serves as a reminder that even seemingly simple functions can contain critical security flaws when proper defensive programming practices are not implemented, emphasizing the need for security-conscious development methodologies in blockchain applications.