CVE-2018-13603 in Briant2Token
Summary
by MITRE
The mintToken function of a smart contract implementation for Briant2Token, 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 as CVE-2018-13603 resides within the mintToken function of the Briant2Token Ethereum smart contract implementation, representing a critical integer overflow flaw that fundamentally compromises the contract's integrity and financial security. This vulnerability stems from improper input validation and arithmetic operations within the smart contract code, where the mintToken function fails to adequately check for overflow conditions when processing token minting operations. The flaw allows the contract owner to manipulate user balances arbitrarily, creating a severe security risk that extends beyond simple financial manipulation to potentially enable complete contract control.
The technical execution of this vulnerability occurs through the manipulation of integer arithmetic operations within the mintToken function, where the contract owner can exploit the lack of overflow checks to set any user's token balance to an arbitrary value. This integer overflow vulnerability directly maps to CWE-191, which specifically addresses integer underflow and overflow conditions, and represents a classic example of how improper boundary checks in smart contract code can lead to catastrophic consequences. The vulnerability operates by allowing the owner to pass malicious values that, when processed through the mintToken function, cause the underlying integer arithmetic to wrap around, resulting in unintended balance modifications. This flaw demonstrates the critical importance of implementing comprehensive input validation and overflow protection mechanisms in blockchain smart contracts, as the Ethereum virtual machine executes these operations without the typical memory safety protections found in conventional software environments.
The operational impact of this vulnerability extends far beyond simple balance manipulation, as it enables the contract owner to potentially drain funds, create artificial token distributions, or even gain unauthorized control over the token economy. An attacker with owner privileges can systematically manipulate user balances to create artificial wealth distribution patterns, potentially enabling them to control token markets or manipulate voting rights within token-based governance systems. The vulnerability also creates a pathway for more sophisticated attacks where the attacker might attempt to exploit the overflow condition to manipulate contract state variables, potentially leading to complete contract compromise. From an ATT&CK framework perspective, this vulnerability aligns with the privilege escalation and resource hijacking techniques, as it allows an authorized user to gain unauthorized control over user assets and contract functionality. The implications for token holders are severe, as they cannot trust the integrity of their balances or the fairness of the token distribution mechanism, potentially leading to complete loss of confidence in the token ecosystem.
Mitigation strategies for CVE-2018-13603 require immediate implementation of comprehensive overflow protection mechanisms within the smart contract code, including explicit bounds checking and the use of safe arithmetic libraries such as OpenZeppelin's SafeMath implementation. The contract owner must implement proper input validation for all parameters passed to the mintToken function, ensuring that all arithmetic operations include overflow and underflow checks before execution. Additionally, the contract should undergo thorough security auditing and formal verification processes to identify and remediate similar vulnerabilities throughout the codebase. Regular code reviews and implementation of security best practices such as the principle of least privilege should be enforced to prevent unauthorized access to administrative functions. The vulnerability also underscores the necessity of implementing multi-signature wallets for critical contract operations and establishing robust monitoring systems to detect unauthorized balance modifications, as these measures provide additional layers of protection against exploitation of similar integer overflow conditions. Organizations should also consider implementing automated testing frameworks that specifically target integer overflow scenarios to ensure comprehensive coverage of potential vulnerabilities in their smart contract implementations.