CVE-2018-13575 in YESToken
Summary
by MITRE
The mintToken function of a smart contract implementation for YESToken, 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 vulnerability identified as CVE-2018-13575 resides within the mintToken function of YESToken smart contract implementation on the Ethereum blockchain. This flaw represents a critical integer overflow vulnerability that fundamentally compromises the contract's integrity and financial security. The vulnerability allows the contract owner to manipulate user balances arbitrarily, effectively enabling unauthorized fund manipulation and potential theft of tokens from other users. The issue stems from improper input validation and lack of overflow checks during arithmetic operations within the mintToken function.
From a technical perspective, the integer overflow occurs when the smart contract performs arithmetic operations without proper bounds checking or overflow detection mechanisms. The mintToken function likely accepts parameters that represent token amounts to be minted or transferred to specific addresses. When these values exceed the maximum limit of the integer data type used, the overflow causes the value to wrap around to an unexpected minimum value, creating a situation where malicious actors can manipulate balances through carefully crafted inputs. This vulnerability falls under CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations.
The operational impact of this vulnerability extends far beyond simple balance manipulation. An attacker with owner privileges can effectively drain funds from other users by setting their balances to zero or transferring all tokens to their own address. The financial implications are severe as users lose complete control over their token holdings, while the contract's reputation suffers from potential loss of user trust. The vulnerability also creates potential for cascading effects where compromised balances might affect other smart contracts that depend on YESToken for functionality, creating broader ecosystem risks.
The attack vector for this vulnerability is particularly concerning as it leverages the contract owner's privileged position to exploit a fundamental flaw in the token distribution mechanism. The attacker needs only to invoke the mintToken function with malicious parameters to execute the attack, making it relatively simple to exploit compared to more complex vulnerabilities. This vulnerability directly aligns with ATT&CK technique T1059.006, which involves the use of smart contracts to execute malicious code or manipulate contract state. The vulnerability also relates to T1499.004, which involves the manipulation of financial assets through code-level exploits.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow checks throughout the smart contract code. Developers should utilize safe math libraries that automatically detect and prevent overflow conditions, such as OpenZeppelin's SafeMath implementation. The contract owner should also implement proper access controls and parameter validation before executing any minting operations. Additionally, comprehensive code auditing and formal verification should be conducted to identify similar vulnerabilities across the entire smart contract implementation. Regular security updates and deployment of patched versions are essential to prevent exploitation, while users should be advised to avoid interacting with vulnerable contracts until proper fixes are implemented. The vulnerability highlights the critical importance of secure coding practices in blockchain environments where financial assets are at stake, emphasizing the need for rigorous testing and validation of all smart contract functions before deployment.