CVE-2018-13540 in GSI
Summary
by MITRE
The mintToken function of a smart contract implementation for GSI, 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 as CVE-2018-13540 represents a critical integer overflow flaw within the mintToken function of a GSI Ethereum token smart contract implementation. This vulnerability resides in the fundamental arithmetic operations of the smart contract code, where insufficient input validation and overflow checking mechanisms allow malicious actors to manipulate token balances. The GSI token contract operates on the Ethereum blockchain, making it susceptible to exploitation by anyone who can control the contract owner account or gain unauthorized access to privileged functions. The integer overflow occurs when the mintToken function processes token minting operations without proper bounds checking, enabling attackers to manipulate the underlying uint256 data types through carefully crafted inputs that exceed maximum representable values.
The technical exploitation of this vulnerability stems from the lack of proper overflow detection mechanisms within the smart contract's arithmetic operations. When the mintToken function attempts to increment token balances or perform calculations involving token quantities, the absence of overflow protection allows for unexpected behavior where large values wrap around to smaller numbers or zero. This flaw directly maps to CWE-190, which specifically addresses integer overflow and underflow conditions in software systems. The vulnerability allows an attacker with owner privileges to manipulate the balance of any user account within the token contract to arbitrary values, effectively enabling unlimited token generation or balance manipulation. This creates a fundamental trust violation in the token economy as the attacker can inflate their own holdings or drain other users' balances through carefully constructed transaction sequences.
The operational impact of this vulnerability extends beyond simple financial loss, as it fundamentally compromises the integrity and security of the entire token ecosystem. Any user whose balance is manipulated by an attacker can experience complete loss of funds or unauthorized token transfers, while the overall token value may become unstable due to the artificial inflation of supply. The vulnerability creates a persistent risk for all token holders since the malicious actor can target any account within the contract, potentially leading to systematic exploitation of user balances. The implications are particularly severe in decentralized finance applications where such vulnerabilities can be exploited to manipulate token prices, create artificial market conditions, or compromise the security of automated trading systems. This type of vulnerability aligns with ATT&CK technique T1548.001, which covers privilege escalation through code injection and manipulation of system resources.
Mitigation strategies for CVE-2018-13540 require immediate implementation of proper overflow protection mechanisms within the smart contract code. Developers should employ explicit bounds checking and use safe arithmetic libraries such as OpenZeppelin's SafeMath implementation to prevent integer overflow conditions. The contract owner should also implement proper access controls and consider using multi-signature wallets for critical functions to reduce the risk of unauthorized access. Regular security audits and formal verification of smart contract code should be conducted to identify similar vulnerabilities in the codebase. Additionally, the contract should implement comprehensive logging of all mintToken operations to detect potential exploitation attempts and maintain an audit trail of all balance modifications. The vulnerability highlights the importance of following secure coding practices in blockchain environments and demonstrates the critical need for thorough testing of arithmetic operations in smart contracts, particularly when dealing with financial applications where the consequences of overflow conditions can be catastrophic.