CVE-2018-13763 in Ublasti
Summary
by MITRE
The mintToken function of a smart contract implementation for Ublasti, 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 • 03/03/2020
The vulnerability identified as CVE-2018-13763 represents a critical integer overflow flaw within the mintToken function of Ublasti token smart contract implementations on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for maximum value limits inherent in integer data types. The flaw allows the contract owner to manipulate token balances in ways that exceed normal operational parameters, creating a fundamental security weakness that undermines the integrity of the token economy.
The technical implementation of this vulnerability occurs when the mintToken function processes token creation requests without proper overflow checks during arithmetic operations. When the contract attempts to increment user balances or perform other mathematical operations on token amounts, the integer overflow condition allows values to wrap around to unexpected states. This behavior manifests when calculations exceed the maximum representable value for the integer type being used, causing the system to store incorrect balance values. The vulnerability specifically aligns with CWE-190, which catalogs integer overflow and underflow issues, and represents a classic example of how improper boundary checking can lead to arbitrary control over system state.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially enable contract owner exploitation for financial gain or system disruption. An attacker with owner privileges could artificially inflate user balances to extremely high values, potentially causing downstream systems to malfunction when processing these inflated amounts. The consequences could include unauthorized token distribution, manipulation of tokenomics, or exploitation of dependent smart contracts that rely on accurate balance calculations. This vulnerability fundamentally compromises the trust model of the token system and could lead to significant financial losses for users and the broader ecosystem.
Mitigation strategies for CVE-2018-13763 require immediate implementation of comprehensive input validation and arithmetic boundary checking within the mintToken function. Smart contract developers should implement explicit overflow checks using modern solidity practices such as require statements with appropriate conditions or utilize SafeMath libraries that prevent arithmetic overflow conditions. The fix must ensure that all balance calculations and token minting operations validate against maximum integer limits before performing any arithmetic operations. Additionally, contract owners should implement proper access controls and audit procedures to monitor for unauthorized balance manipulations, while the broader Ethereum ecosystem benefits from enhanced smart contract security auditing practices that can identify similar vulnerabilities before deployment. This vulnerability demonstrates the critical importance of adhering to secure coding practices and following ATT&CK framework considerations for smart contract security operations that prevent privilege escalation through arithmetic manipulation techniques.