CVE-2018-13731 in TokenMACHU
Summary
by MITRE
The mintToken function of a smart contract implementation for TokenMACHU, 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 • 02/28/2020
The vulnerability identified in CVE-2018-13731 represents a critical integer overflow flaw within the mintToken function of the TokenMACHU smart contract deployed on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic overflow handling within the contract's code implementation. The flaw specifically manifests when the mintToken function processes token minting operations, allowing unauthorized manipulation of user balances through crafted input parameters. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, which occurs when an arithmetic operation produces a result that exceeds the maximum value that can be represented by the target data type. The root cause lies in the contract's failure to properly validate the parameters passed to the mintToken function, particularly the amount parameter that controls how many tokens are minted and credited to a specific user account. This allows an attacker with access to the contract owner privileges to manipulate the token supply and user balances in ways that could lead to significant financial loss and system compromise.
The operational impact of this vulnerability extends beyond simple balance manipulation to encompass potential system-wide destabilization and financial fraud. An attacker with owner privileges can exploit this vulnerability to inflate user balances to arbitrary values, potentially creating unlimited token supply or manipulating the balances of other users to gain unfair advantages. The vulnerability creates a pathway for unauthorized token distribution and could enable attackers to drain the contract's token reserves or manipulate the tokenomics of the entire system. This type of vulnerability directly impacts the integrity and availability of the smart contract system, as it allows for manipulation of core accounting functions that are fundamental to any token-based system. The attack vector is particularly concerning because it requires only owner privileges, which are typically limited to authorized parties, but if compromised, could lead to complete system takeover. The vulnerability also introduces risks related to the token's reputation and trustworthiness within the Ethereum ecosystem, as it could be exploited to create artificial market conditions or manipulate token prices through balance manipulation.
Security mitigations for this vulnerability require immediate implementation of proper input validation and arithmetic overflow protection mechanisms within the smart contract code. The fix should involve adding bounds checking and overflow detection before any arithmetic operations occur within the mintToken function, ensuring that the amount parameter cannot exceed the maximum representable value for the target data type. Developers should implement comprehensive parameter validation that includes checking for negative values, maximum value limits, and ensuring that the total supply does not exceed predefined thresholds. The contract should also incorporate proper access control mechanisms to prevent unauthorized use of owner functions and implement event logging for all token minting operations to enable monitoring and auditing. Additionally, regular smart contract audits and formal verification processes should be conducted to identify similar vulnerabilities before deployment. Organizations should also consider implementing multi-signature wallets for owner functions and establish strict governance procedures for contract upgrades. This vulnerability aligns with ATT&CK technique T1548.001 related to privilege escalation and T1078.004 related to valid accounts, as it exploits legitimate owner privileges to perform unauthorized operations. The fix should also include implementing proper gas limit checks and transaction validation to prevent potential denial-of-service attacks that could exploit the same vulnerability in different contexts.