CVE-2018-13499 in Crowdsale
Summary
by MITRE
The mintToken function of a smart contract implementation for Crowdsale, 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 mintToken function in the Ethereum smart contract implementation for Crowdsale contains a critical integer overflow vulnerability that fundamentally compromises the contract's integrity and security. This vulnerability arises from insufficient input validation and arithmetic overflow handling within the mintToken function, allowing an attacker with owner privileges to manipulate token balances arbitrarily. The flaw enables the contract owner to set any user's token balance to an arbitrary value, potentially leading to unlimited token creation and unauthorized balance manipulation. This represents a severe compromise of the contract's core functionality and trust model.
The technical nature of this vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses situations where integer arithmetic operations produce results that exceed the maximum value that can be represented by the data type. In Ethereum smart contracts, this typically occurs when operations involving uint256 variables exceed their maximum value of 2^256 - 1, causing the value to wrap around to zero or a negative value. The mintToken function lacks proper bounds checking and overflow protection mechanisms that would normally prevent such arithmetic anomalies from being exploited.
The operational impact of this vulnerability is devastating for any token holders and investors who rely on the integrity of the Crowdsale contract. An attacker with owner access can manipulate token distributions to create unlimited tokens, effectively undermining the economic model and value proposition of the token. This vulnerability directly enables several attack vectors including token inflation, unauthorized balance manipulation, and potential theft of funds. The compromised contract state means that all users' balances become unreliable, as the owner can arbitrarily adjust them without detection. The vulnerability also creates a fundamental trust issue in the entire token ecosystem, as users cannot verify their actual balances or transaction history.
From a cybersecurity perspective, this vulnerability maps to several ATT&CK techniques including T1059.001 Command and Scripting Interpreter and T1548.001 Abuse of Functionality, as it allows attackers to exploit legitimate contract functions for malicious purposes. The vulnerability also aligns with T1499.004 Network Denial of Service through contract manipulation and T1566.002 Phishing with Spoofing in the context of token value manipulation. Organizations and individuals should immediately audit their smart contract implementations for similar integer overflow vulnerabilities and implement proper overflow protection mechanisms such as safeMath libraries or explicit bounds checking. The vulnerability demonstrates the critical importance of rigorous smart contract auditing and the need for comprehensive security testing before deployment. Additionally, the use of formal verification methods and automated security analysis tools should be considered to prevent similar issues in future implementations. The incident highlights the necessity of implementing proper access controls and multi-signature requirements for contract owner privileges to limit the potential damage from such vulnerabilities.