CVE-2018-13659 in BrianCoin
Summary
by MITRE
The mintToken function of a smart contract implementation for BrianCoin, 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-2018-13659 represents a critical integer overflow flaw within the mintToken function of the BrianCoin Ethereum smart contract implementation. This vulnerability stems from improper input validation and arithmetic handling within the contract's codebase, creating a scenario where the contract owner can manipulate user balances arbitrarily. The flaw occurs when the mintToken function processes token minting operations without adequate overflow checks, allowing malicious actors with owner privileges to execute calculations that exceed the maximum value representable by the integer data type. Such vulnerabilities fall under the CWE-190 category of Integer Overflow or Wraparound, which is classified as a high-severity issue in software security assessments.
The technical execution of this vulnerability involves the contract owner exploiting the lack of bounds checking in the mintToken function to perform arithmetic operations that result in unexpected behavior. When the contract attempts to increment a user's balance through minting operations, the integer overflow allows the owner to manipulate the resulting value to any desired amount. This occurs because the smart contract fails to validate that the addition operation will remain within the valid range of the integer data type. The vulnerability is particularly dangerous as it directly impacts the contract's integrity and user fund security, enabling the owner to create unlimited tokens or manipulate existing balances without detection. According to ATT&CK framework, this represents a privilege escalation technique where an attacker with owner privileges can manipulate the contract state through code-level vulnerabilities.
The operational impact of this vulnerability extends beyond simple balance manipulation to encompass potential financial losses and contract integrity breaches. An attacker with owner access can inflate user balances to create artificial wealth or reduce balances to zero, effectively enabling theft of funds or manipulation of the token economy. The vulnerability undermines the fundamental trust in the smart contract's token distribution mechanism and can lead to significant financial losses for users who hold BrianCoin tokens. Additionally, this flaw can compromise the entire token ecosystem by allowing the contract owner to bypass normal tokenomics and potentially create a scenario where the token supply becomes unstable or the economic model is fundamentally compromised. The vulnerability's exploitation requires minimal technical knowledge and can be executed through standard Ethereum transaction mechanisms, making it particularly dangerous in production environments where such contracts are actively used.
Mitigation strategies for CVE-2018-13659 must focus on implementing proper integer overflow protections within the smart contract code. Developers should incorporate comprehensive input validation and use safe arithmetic operations that check for overflow conditions before performing calculations. The recommended approach includes implementing bounds checking mechanisms, utilizing established libraries such as OpenZeppelin's SafeMath for arithmetic operations, and conducting thorough code audits to identify similar vulnerabilities. Additionally, contract owners should implement proper access controls and consider using multi-signature wallets for critical operations to reduce the risk of unauthorized exploitation. The vulnerability highlights the importance of following secure coding practices in blockchain development, particularly regarding data type handling and arithmetic operations, as outlined in industry standards for smart contract security. Regular security assessments and continuous monitoring of smart contract implementations are essential to prevent similar vulnerabilities from emerging in future deployments.