CVE-2018-13563 in UPayToken
Summary
by MITRE
The mintToken function of a smart contract implementation for UPayToken, 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 CVE-2018-13563 vulnerability represents a critical integer overflow flaw within the mintToken function of the UPayToken smart contract implementation on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic overflow handling within the contract's token minting mechanism, creating a fundamental security weakness that directly impacts the contract's integrity and user asset safety. The flaw allows the contract owner to manipulate user balances arbitrarily, fundamentally compromising the token's trust model and potentially enabling unauthorized wealth transfer operations.
The technical implementation of this vulnerability occurs when the mintToken function processes token minting operations without proper bounds checking on the amount parameter. In Ethereum smart contracts, integer overflows occur when arithmetic operations exceed the maximum value that can be stored in a variable's data type, causing the value to wrap around to zero or negative numbers. This specific implementation lacks proper overflow protection mechanisms, making it susceptible to attackers who can manipulate the mintToken function parameters to create unintended balance states. The vulnerability is classified as a CWE-191 Integer Underflow/Overflow, which represents a common class of flaws in smart contract development where developers fail to account for arithmetic boundary conditions.
The operational impact of this vulnerability extends beyond simple balance manipulation, creating potential for significant financial loss and system compromise. An attacker with owner privileges can exploit this flaw to inflate user balances to extremely high values or even set them to zero, effectively allowing for unauthorized fund transfers or account manipulation. The vulnerability directly affects the token's supply mechanism and user account integrity, potentially enabling the creation of infinite tokens or the complete depletion of user balances. This flaw undermines the fundamental principles of blockchain tokenomics and could lead to complete loss of user funds, contract functionality, and trust in the token ecosystem. The impact is particularly severe because it allows for manipulation of user balances without requiring external interaction, making it a silent but powerful attack vector.
Mitigation strategies for CVE-2018-13563 require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. The primary solution involves adding explicit bounds checking and overflow protection using modern Solidity practices such as SafeMath library implementations or compiler version upgrades that include built-in overflow protection. Contract owners must implement comprehensive input validation for all user-supplied parameters, particularly those used in minting and transfer operations. Additionally, regular security audits and formal verification processes should be conducted to identify similar vulnerabilities across the entire contract codebase. The remediation aligns with ATT&CK technique T1548.001 for privilege escalation and T1499.004 for data manipulation, emphasizing the need for robust access controls and data integrity measures. Organizations should also implement proper contract access controls, regular monitoring of balance changes, and emergency response procedures to address such vulnerabilities promptly.