CVE-2018-13217 in CoinToken
Summary
by MITRE
The sell function of a smart contract implementation for CoinToken, an Ethereum token, has an integer overflow in which "amount * sellPrice" can be zero, consequently reducing a seller's assets.
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Analysis
by VulDB Data Team • 02/25/2020
The vulnerability identified as CVE-2018-13217 resides within the smart contract implementation of CoinToken, an Ethereum-based token system that demonstrates a critical integer overflow flaw in its sell function. This vulnerability stems from improper input validation and arithmetic operation handling within the contract's code, specifically when processing token sales transactions. The flaw manifests when the multiplication operation "amount * sellPrice" results in zero, which occurs due to the contract's failure to properly validate or handle large integer values that exceed the maximum representable range for the data types used.
The technical implementation of this vulnerability involves the contract's sell function executing arithmetic operations without adequate overflow protection mechanisms. When a seller attempts to sell tokens, the contract calculates the payout by multiplying the token amount with the current sell price, but due to the integer overflow, this calculation can produce unexpected zero values instead of the expected monetary compensation. This condition arises because the contract does not implement proper bounds checking or overflow detection before performing the multiplication operation, making it susceptible to mathematical overflow scenarios where large values wrap around to zero or negative numbers.
From an operational perspective, this vulnerability creates a significant financial risk for token holders who wish to sell their assets. The zero result from the multiplication operation effectively nullifies the seller's ability to receive proper compensation for their tokens, resulting in asset loss and potential financial fraud. Attackers can exploit this flaw by manipulating the sell price or token amount to trigger the overflow condition, thereby executing a form of financial manipulation that undermines the contract's core functionality and trust model. This vulnerability directly impacts the contract's integrity and can lead to substantial financial losses for users who rely on the token's sell functionality.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations. It also corresponds to ATT&CK technique T1499.004, which covers network denial of service through smart contract manipulation, as the vulnerability can be exploited to create a state where legitimate transactions fail to execute properly. Additionally, this flaw demonstrates characteristics of T1548.001, privilege escalation through smart contract manipulation, as it allows malicious actors to manipulate contract state in ways that benefit their own holdings while harming legitimate users.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. Developers should employ explicit bounds checking and use libraries such as OpenZeppelin's SafeMath for arithmetic operations to prevent overflow conditions. The contract should validate all input parameters before performing calculations and implement proper error handling to prevent zero-value transactions from being processed. Additionally, comprehensive testing including edge case scenarios and stress testing should be conducted to ensure that the arithmetic operations behave correctly under all conditions. Regular security audits and formal verification processes should be implemented to identify similar vulnerabilities in other contract functions and prevent future occurrences of such integer overflow conditions that could compromise the entire token ecosystem.