CVE-2018-13542 in ZIBToken
Summary
by MITRE
The mintToken function of a smart contract implementation for ZIBToken, 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 in CVE-2018-13542 represents a critical integer overflow flaw within the mintToken function of the ZIBToken smart contract implementation 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 crafted transactions. The flaw exists specifically in the mintToken function which is designed to create new tokens and assign them to user addresses, but due to insufficient overflow checks, it allows for arbitrary value manipulation. The vulnerability is classified under CWE-190, which details integer overflow and underflow conditions, and represents a fundamental weakness in the contract's arithmetic handling that directly impacts the integrity of the token ecosystem. When an attacker exploits this vulnerability, they can cause the balance of any user account to be set to an arbitrary value, potentially leading to massive financial losses for token holders and undermining the entire token economy.
The technical implementation of this vulnerability occurs within the mintToken function where the smart contract performs arithmetic operations without proper bounds checking. In Ethereum smart contracts, integer overflows typically occur when operations exceed the maximum value that can be represented by the data type, causing the value to wrap around to zero or negative numbers. The specific flaw in ZIBToken allows an attacker to manipulate the mintToken function such that when the contract attempts to increment a user's balance, the arithmetic operation overflows and produces an unintended result. This overflow can be leveraged to set any user's balance to an extremely large value, effectively creating unlimited tokens for that user or potentially setting balances to zero. The vulnerability is particularly dangerous because it operates at the contract level and can be exploited by the contract owner, who has privileged access to execute the mintToken function, making it a severe governance risk within the token system.
The operational impact of this vulnerability extends beyond immediate financial loss to encompass broader ecosystem stability and trust degradation. When an attacker successfully exploits this integer overflow, they can manipulate token distributions in ways that fundamentally alter the token's economic model, potentially enabling them to drain the contract's resources or create artificial inflation. The vulnerability allows for manipulation of user balances, which can result in unauthorized access to funds, creation of fraudulent token distributions, and potential disruption of token trading markets. This type of vulnerability directly impacts the security posture of the entire Ethereum ecosystem as it demonstrates how seemingly simple arithmetic operations can lead to catastrophic consequences when proper validation is absent. The exploitation of such vulnerabilities can lead to complete loss of funds for token holders, undermine investor confidence, and potentially result in regulatory scrutiny of the entire token project. According to ATT&CK framework, this vulnerability maps to T1068 which involves exploiting remote services, and T1210 which covers exploitation of remote services, specifically targeting the smart contract execution environment.
Mitigation strategies for this vulnerability require immediate implementation of comprehensive input validation and arithmetic operation safeguards within the smart contract code. The most effective approach involves adding explicit overflow checks before any arithmetic operations that could potentially exceed integer limits, utilizing safe math libraries or built-in overflow protection mechanisms available in modern Ethereum development frameworks. Contract owners should implement proper access controls and consider using multi-signature wallets for executing mintToken functions to prevent unauthorized exploitation. The recommended remediation includes replacing vulnerable arithmetic operations with checked versions that explicitly verify results before assignment, ensuring that balance updates cannot exceed reasonable limits. Additionally, comprehensive testing including fuzz testing and formal verification should be conducted to identify similar vulnerabilities in other contract functions. The vulnerability also highlights the importance of adhering to established security standards and best practices such as those outlined in the Ethereum Smart Contract Security Best Practices document, which emphasizes the need for rigorous input validation and proper handling of integer arithmetic operations. Regular security audits and continuous monitoring of smart contract deployments are essential to prevent similar vulnerabilities from being introduced in future contract implementations.