CVE-2018-13704 in eddToken
Summary
by MITRE
The mintToken function of a smart contract implementation for eddToken, 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 mintToken function in the eddToken smart contract implementation contains a critical integer overflow vulnerability that fundamentally compromises the token's integrity and security model. This vulnerability resides in the contract's ability to mint new tokens and assign them to user accounts, creating a scenario where the contract owner can manipulate token balances beyond normal operational parameters. The flaw specifically manifests when the contract attempts to increment token balances, allowing for values that exceed the maximum limits of the integer data types used in the implementation. This represents a direct violation of the fundamental principles of blockchain tokenomics where each user's balance should be accurately tracked and immutable except through legitimate transactions. The vulnerability stems from inadequate input validation and overflow checking mechanisms within the mintToken function, enabling malicious actors with owner privileges to manipulate the total supply and individual user balances at will. According to CWE-190, this vulnerability maps directly to integer overflow conditions that occur when a computation results in a value that exceeds the maximum value that can be represented by the underlying data type, creating a dangerous attack surface for smart contract systems.
The operational impact of this vulnerability extends far beyond simple balance manipulation, creating potential for significant financial loss and system compromise within the token ecosystem. An attacker with access to the contract owner account can arbitrarily set any user's balance to any value, including potentially infinite amounts, which would allow for unlimited spending and transfer capabilities. This vulnerability effectively nullifies the security assumptions that users rely upon when interacting with the token, as the fundamental accounting mechanism becomes compromised. The implications are particularly severe in decentralized finance applications where token balances directly control access to funds and system permissions. Attackers could exploit this to create artificial wealth in their accounts, manipulate token distribution, or even cause the contract to behave unpredictably when attempting to process transactions involving affected accounts. The vulnerability also enables potential denial-of-service scenarios where an attacker could set balances to values that cause the contract to fail during normal operations. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques where an attacker leverages existing administrative access to gain further control over the system's financial state, potentially enabling subsequent attacks on other components that rely on the integrity of token balances.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements to prevent similar issues in future implementations. The immediate fix requires implementing proper integer overflow checks using safe arithmetic operations or employing established libraries such as OpenZeppelin's SafeMath that prevent overflows through explicit validation. The contract should validate all input parameters to the mintToken function, ensuring that balance additions do not exceed maximum integer limits and that the resulting values remain within acceptable bounds. Additionally, implementing comprehensive access controls and multi-signature requirements for owner functions can reduce the attack surface by preventing single points of failure. Regular security audits and formal verification of smart contract code should become standard practice to identify similar vulnerabilities before they can be exploited. The implementation should also include proper event logging and monitoring capabilities to detect anomalous balance changes that might indicate exploitation attempts. Organizations should consider adopting industry best practices such as those outlined in the Ethereum Smart Contract Security Best Practices document, which emphasizes the importance of defensive programming and comprehensive testing to prevent integer overflow conditions. The vulnerability also highlights the necessity of implementing robust testing methodologies including fuzz testing and property-based testing to identify edge cases that might lead to similar issues in token implementations.