CVE-2018-13473 in ohni_2
Summary
by MITRE
The mintToken function of a smart contract implementation for ohni_2 (OHNI), 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 • 02/26/2020
The vulnerability identified in CVE-2018-13473 represents a critical integer overflow flaw within the mintToken function of the ohni_2 (OHNI) Ethereum token smart contract implementation. This vulnerability stems from improper input validation and arithmetic handling within the contract's code, creating a scenario where the contract owner can manipulate user balances arbitrarily. The issue manifests when the mintToken function processes token minting operations without adequate overflow checks, allowing malicious or accidental manipulation of balance values beyond the intended limits.
The technical exploitation of this vulnerability occurs through the manipulation of integer arithmetic operations within the smart contract's mintToken function. When the contract attempts to increment user balances or perform token creation operations, the lack of proper overflow detection enables attackers to cause unsigned integer overflows. This results in the balance values wrapping around to extremely large or small values, effectively allowing the contract owner to set any user's balance to an arbitrary value. The vulnerability directly maps to CWE-190, which specifically addresses integer overflow and underflow conditions, and represents a classic example of improper integer handling in smart contract environments. The flaw exists because the contract implementation fails to validate that arithmetic operations remain within the bounds of the data type being used, particularly when dealing with uint256 or similar unsigned integer types.
The operational impact of this vulnerability extends beyond simple balance manipulation and creates significant risks for token holders and the overall ecosystem. Contract owners can exploit this vulnerability to artificially inflate or deflate user balances, potentially leading to unauthorized token distribution or depletion of user holdings. The consequences include immediate financial loss for affected users, potential market manipulation through artificial balance creation, and erosion of trust in the token's integrity. Additionally, this vulnerability creates opportunities for attackers to perform reentrancy attacks or other complex exploitation patterns that leverage the manipulated balances. The impact is particularly severe in decentralized finance contexts where such token manipulations can affect lending protocols, staking mechanisms, or other smart contract interactions that depend on accurate balance calculations. This vulnerability also aligns with ATT&CK technique T1499.004, which covers the manipulation of information, as it allows for unauthorized modification of critical token balance data that forms the foundation of the token's value and functionality.
Mitigation strategies for this vulnerability require immediate code remediation through comprehensive input validation and overflow protection mechanisms. The smart contract implementation must incorporate explicit overflow checks using modern Solidity practices such as require statements with bounds validation or the use of SafeMath libraries that prevent arithmetic overflows. Contract owners should implement proper access controls and audit procedures to identify and address similar vulnerabilities in other functions. The remediation process involves adding comprehensive validation checks to ensure that all balance modifications adhere to expected value ranges and that arithmetic operations maintain integrity throughout the execution flow. Additionally, regular security audits and formal verification processes should be implemented to identify potential integer overflow vulnerabilities before deployment. Organizations should also consider implementing multi-signature wallets for contract ownership and establish clear governance procedures for contract modifications to prevent unauthorized exploitation of such vulnerabilities. The fix must address not only the immediate mintToken function but also review all other functions that perform arithmetic operations to ensure comprehensive protection against similar integer overflow scenarios.