CVE-2018-13636 in TurdCoin
Summary
by MITRE
The mintToken function of a smart contract implementation for TurdCoin, 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 vulnerability identified in CVE-2018-13636 represents a critical integer overflow flaw within the mintToken function of the TurdCoin Ethereum smart contract implementation. This vulnerability resides in the core token management functionality that allows the contract owner to create new tokens and distribute them to users. The integer overflow occurs when the contract attempts to increment token balances without proper bounds checking, creating a scenario where arithmetic operations can wrap around to unexpected values. Such flaws are particularly dangerous in blockchain environments where financial assets are at stake and where the immutable nature of smart contracts makes remediation extremely difficult once deployed on the mainnet.
The technical exploitation of this vulnerability stems from the lack of input validation and overflow protection within the mintToken function implementation. When the contract owner invokes this function to mint new tokens for a specific user, the underlying code fails to verify that the resulting balance would not exceed the maximum value representable by the integer data type. This allows an attacker with owner privileges to manipulate the balance calculation such that the arithmetic overflow produces an arbitrary target value, effectively enabling the owner to set any user's token balance to any desired amount. The vulnerability directly maps to CWE-190, which describes integer overflow and underflow conditions, and represents a classic example of how improper integer handling can lead to severe financial consequences in decentralized applications.
The operational impact of this vulnerability extends far beyond simple balance manipulation, as it fundamentally compromises the integrity of the token economy. An attacker with owner access could potentially inflate token supplies, create unlimited balances for malicious addresses, or manipulate token distributions to gain unfair advantages in token-based systems. This type of vulnerability enables what security researchers categorize as privilege escalation attacks within the MITRE ATT&CK framework, specifically falling under the category of privilege escalation through code injection or manipulation of system state. The implications for token holders, exchanges, and the broader ecosystem are severe, as such manipulation can lead to market manipulation, loss of confidence in the token, and potential financial losses for users who hold the affected tokens.
Mitigation strategies for this vulnerability require immediate attention from contract owners and developers. The most effective approach involves implementing comprehensive input validation and overflow protection mechanisms within the smart contract code, utilizing safe arithmetic operations that explicitly check for overflow conditions before performing calculations. The fix should include explicit bounds checking on all balance modifications and the implementation of overflow protection patterns such as those recommended by the Solidity documentation and security best practices. Additionally, contract owners should conduct thorough security audits and employ formal verification methods to identify similar vulnerabilities across their entire smart contract ecosystem. The remediation process must also consider the importance of access control mechanisms, ensuring that only authorized parties can invoke privileged functions, and implementing multi-signature requirements for critical operations. This vulnerability highlights the critical importance of adhering to established security standards and best practices in smart contract development, as even minor oversights in arithmetic operations can lead to catastrophic financial consequences in decentralized systems.