CVE-2018-13694 in Gmile
Summary
by MITRE
The mintToken function of a smart contract implementation for GMile, 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-2018-13694 represents a critical integer overflow flaw within the mintToken function of GMile smart contract implementation on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for boundary conditions in the token minting process. The flaw allows an attacker with owner privileges to manipulate token balances by setting arbitrary values for user accounts, effectively bypassing normal token distribution mechanisms and creating a potential avenue for unauthorized value manipulation.
The technical nature of this vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions where an integer value exceeds the maximum representable value for its data type. In the context of Ethereum smart contracts, this overflow occurs during the mintToken function execution when the contract attempts to increment token balances without proper bounds checking. The vulnerability exists because the contract does not validate that the addition operation will not exceed the maximum value for the integer data type, allowing an attacker to craft inputs that cause the arithmetic to wrap around to unintended values.
From an operational perspective, this vulnerability creates a severe risk to the token ecosystem as it enables the contract owner to manipulate user balances to arbitrary values including potentially infinite amounts. The impact extends beyond simple balance manipulation since it could allow for the creation of unlimited tokens, disruption of normal trading operations, and potential financial loss for token holders. The vulnerability's exploitability is enhanced by the fact that it requires only owner privileges, which are typically limited but still represent a significant trust assumption within the token governance model.
The ATT&CK framework categorizes this vulnerability under privilege escalation and resource hijacking tactics, as it allows an attacker to gain unauthorized control over token resources through manipulation of the smart contract's core functionality. The vulnerability demonstrates a fundamental flaw in the contract's access control and input validation mechanisms, creating a pathway for malicious actors to compromise the token's integrity. Additionally, this issue represents a failure in the secure coding practices typically expected in blockchain applications, where the immutable nature of smart contracts makes such vulnerabilities particularly dangerous.
Mitigation strategies should focus on implementing comprehensive input validation and bounds checking within the mintToken function to prevent arithmetic overflow conditions. The contract should utilize safe arithmetic libraries or built-in overflow protection mechanisms available in modern Ethereum development frameworks. Regular security audits and formal verification processes should be implemented to identify similar vulnerabilities before deployment. The contract owner should also consider implementing additional access controls and multi-signature requirements for critical functions to reduce the risk of unauthorized exploitation. Furthermore, developers should adopt defensive programming practices including explicit overflow checks and comprehensive testing of edge cases to prevent similar vulnerabilities in future implementations.