CVE-2018-13089 in Universal Coin
Summary
by MITRE
The mintToken function of a smart contract implementation for Universal Coin (UCOIN), 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 • 02/24/2020
The vulnerability identified in CVE-2018-13089 represents a critical integer overflow flaw within the mintToken function of the Universal Coin (UCOIN) smart contract deployed on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types, creating a scenario where malicious actors can manipulate token balances through controlled overflow conditions. The flaw specifically affects the contract's ability to safely handle large numeric values during token creation and distribution processes.
The technical implementation of this vulnerability manifests through the mintToken function's failure to validate whether the addition of new tokens to a user's balance would exceed the maximum value that can be represented by the underlying integer type. When the contract attempts to increment a user's balance with newly minted tokens, an integer overflow occurs if the resulting value surpasses the maximum allowable integer limit, causing the value to wrap around to zero or a negative number. This overflow behavior allows the contract owner to manipulate the balance calculations in a predictable manner, effectively enabling arbitrary balance manipulation.
From an operational perspective, this vulnerability creates a severe security risk for the Universal Coin ecosystem as it grants the contract owner unlimited control over user token balances. The attacker can exploit this flaw to artificially inflate or deflate any user's token holdings, potentially enabling unauthorized wealth redistribution, manipulation of token exchange rates, or creation of artificial scarcity. The impact extends beyond simple balance manipulation to potentially compromise the entire token economy, as users may lose trust in the system's integrity and the underlying value of their holdings becomes uncertain. This vulnerability fundamentally undermines the core principles of blockchain-based asset management and smart contract security.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations, and maps to ATT&CK technique T1548.001 for privilege escalation through smart contract manipulation. The attack vector requires the contract owner's private key access, making it a high-severity issue that could be exploited for financial gain or system compromise. Organizations should implement comprehensive input validation, utilize safe arithmetic libraries, and conduct thorough code audits to prevent similar vulnerabilities in future smart contract deployments. The remediation process involves implementing proper overflow checks, utilizing established cryptographic libraries, and ensuring that all arithmetic operations within smart contracts are designed to handle edge cases without compromising system integrity.