CVE-2018-13689 in CJXToken
Summary
by MITRE
The mintToken function of a smart contract implementation for CJXToken, 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-2018-13689 represents a critical integer overflow flaw within the mintToken function of the CJXToken Ethereum smart contract implementation. This vulnerability falls under the CWE-190 category of integer overflow and under the ATT&CK technique T1059.001 for execution through smart contracts. The flaw exists in the token contract's logic where the mintToken function fails to properly validate or constrain integer values during balance calculations, creating a scenario where the owner can manipulate token balances beyond normal operational limits. The vulnerability specifically impacts the contract's ability to maintain accurate and secure token accounting, as it allows for arbitrary balance manipulation without proper authorization checks.
The technical exploitation of this vulnerability occurs when the contract owner invokes the mintToken function with malicious parameters that cause integer overflow conditions. When the contract processes token minting operations, it performs arithmetic operations on token balances without proper overflow detection mechanisms. This allows the attacker to supply values that, when processed through the contract's internal calculations, result in unexpected behavior where the balance of any user account can be set to an arbitrary value. The integer overflow creates a condition where the calculation wraps around to a smaller value, effectively bypassing normal balance constraints and allowing for unauthorized balance manipulation.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token economy and user trust in the system. An attacker with owner privileges can increase any user's balance to extremely high values, potentially leading to inflationary effects that devalue the token for other users. The vulnerability also creates opportunities for denial of service attacks where malicious actors might set balances to zero or extremely low values, effectively freezing user accounts. Additionally, the vulnerability undermines the fundamental security assumptions of the token contract, as it allows for unauthorized value manipulation that bypasses normal access control mechanisms and smart contract security models.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protections within the smart contract code. The recommended approach involves adding explicit bounds checking and validation before any arithmetic operations are performed on token balances, utilizing safe math libraries or implementing custom overflow detection routines. The contract owner should also consider implementing additional access controls and transaction monitoring to detect unusual balance manipulation patterns. Security audits should be conducted to identify and remediate similar vulnerabilities across all smart contract functions that perform arithmetic operations. Organizations should adopt security frameworks such as the OpenZeppelin safe math libraries or similar proven solutions that provide built-in overflow protection mechanisms to prevent similar issues in future smart contract implementations. The vulnerability demonstrates the critical importance of proper input validation and arithmetic operation safety in blockchain smart contracts, as outlined in the Ethereum Smart Contract Security Best Practices and the OWASP Smart Contract Security Verification Standard.