CVE-2018-13644 in RoyalClassicCoin
Summary
by MITRE
The mintToken function of a smart contract implementation for RoyalClassicCoin, 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-2018-13644 represents a critical integer overflow flaw within the mintToken function of the RoyalClassicCoin Ethereum token smart contract. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types. The flaw allows the contract owner to manipulate token balances of arbitrary users by exploiting the overflow behavior, effectively enabling unauthorized minting of tokens beyond intended limits.
The technical implementation of this vulnerability demonstrates a classic case of unchecked arithmetic operations within smart contract code. When the mintToken function processes token minting requests, it performs calculations without proper overflow checks, particularly when dealing with large integer values that exceed the maximum capacity of the underlying data types. This condition creates a scenario where arithmetic operations wrap around to zero or negative values, enabling the contract owner to manipulate user balances arbitrarily. The vulnerability specifically affects the uint256 data type handling within the Ethereum Virtual Machine, where operations exceeding maximum values cause wraparound behavior rather than throwing exceptions.
The operational impact of this vulnerability extends beyond simple financial manipulation to encompass potential system compromise and user fund theft. An attacker with owner privileges can exploit this flaw to inflate user balances to arbitrary values, potentially enabling them to drain the contract's token supply or manipulate market dynamics. The vulnerability also creates trust issues within the token ecosystem, as users cannot rely on the integrity of their token balances. Additionally, this flaw may enable more sophisticated attacks such as reentrancy exploits or other contract manipulation techniques that leverage the compromised balance state.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and arithmetic boundary checks within the smart contract code. The recommended approach involves adding explicit overflow checks using require statements before any arithmetic operations that could potentially exceed integer limits. Developers should implement comprehensive testing procedures including fuzz testing and formal verification to identify similar vulnerabilities across the entire contract codebase. The solution aligns with CWE-191, which specifically addresses integer underflow and overflow conditions, and follows ATT&CK framework techniques related to smart contract manipulation and privilege escalation. Proper implementation of these mitigations ensures that the mintToken function validates all inputs and performs arithmetic operations within safe boundaries, preventing unauthorized balance manipulation while maintaining the contract's intended functionality.