CVE-2018-13489 in OllisCoin
Summary
by MITRE
The mintToken function of a smart contract implementation for OllisCoin, 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 in CVE-2018-13489 represents a critical integer overflow flaw within the mintToken function of OllisCoin smart contract implementation on the Ethereum blockchain. This vulnerability stems from inadequate input validation and arithmetic overflow handling in the contract's token minting mechanism. The flaw allows the contract owner to manipulate user balances arbitrarily, effectively creating a scenario where unauthorized value manipulation can occur within the token ecosystem. The vulnerability manifests when the mintToken function processes token creation requests without proper bounds checking, enabling attackers to exploit the mathematical overflow properties inherent in fixed-size integer representations.
The technical implementation of this vulnerability directly maps to CWE-190, which specifically addresses integer overflow conditions in software systems. In the context of Ethereum smart contracts, this represents a classic overflow vulnerability that occurs when arithmetic operations exceed the maximum value that can be represented by the underlying data type. The mintToken function likely performs operations that assume integer values will remain within safe bounds, but fails to validate that the resulting values do not exceed the maximum representable value for the data type used. This creates a scenario where the overflow can be manipulated to produce predictable and exploitable outcomes, particularly when dealing with balance updates and token minting operations.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token economy and user trust within the OllisCoin ecosystem. An attacker with owner privileges can arbitrarily set any user's balance to any value, including negative balances or values exceeding the total token supply. This capability enables several malicious scenarios including creating unlimited tokens, manipulating user balances to gain unfair advantages, or even potentially causing the token contract to behave unpredictably when the overflow conditions are triggered. The vulnerability effectively undermines the fundamental security assumptions of the token contract and can lead to complete loss of value for users who trust the contract's integrity.
Mitigation strategies for CVE-2018-13489 require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. The recommended approach involves implementing comprehensive input validation and bounds checking before any arithmetic operations occur, particularly in functions that handle token minting and balance updates. This includes utilizing safe arithmetic libraries or implementing explicit overflow checks using require statements that validate all input parameters and intermediate calculation results. The contract should also implement proper access controls to ensure only authorized parties can invoke mintToken functions, while additionally incorporating defensive programming practices such as using overflow-safe libraries like OpenZeppelin's SafeMath implementation. Additionally, regular security audits and formal verification of smart contract code should be conducted to identify and remediate similar vulnerabilities before they can be exploited in production environments.
This vulnerability also aligns with several ATT&CK techniques including T1059.001 for command and scripting interpreter and T1548.001 for abuse of system privileges, as it allows privilege escalation through the manipulation of contract owner functions. The attack surface is particularly concerning given that Ethereum smart contracts operate in a trustless environment where such vulnerabilities can be exploited by anyone who gains access to the owner private key, making proper vulnerability management and access control critical components of any blockchain security strategy.