CVE-2018-13586 in Nectar
Summary
by MITRE
The mintToken function of a smart contract implementation for Nectar (NCTR), 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.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/27/2020
The vulnerability identified in CVE-2018-13586 affects the Nectar (NCTR) token smart contract deployed on the Ethereum blockchain, representing a critical security flaw that fundamentally compromises the contract's integrity and user fund safety. This issue manifests within the mintToken function, which serves as a mechanism for creating new tokens and distributing them to users. The vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types, creating an exploitable condition that allows malicious actors to manipulate token balances beyond normal operational parameters.
The technical flaw constitutes an integer overflow vulnerability, specifically classified under CWE-190 as an integer overflow or wraparound, which occurs when an arithmetic operation attempts to create a result that exceeds the maximum value representable by the underlying data type. In the context of Ethereum smart contracts, this vulnerability arises from the absence of proper bounds checking in the mintToken function, allowing an attacker with owner privileges to manipulate the balance of any user account within the contract. The vulnerability exists because the contract's implementation does not verify that the addition of new tokens to a user's balance will not exceed the maximum value that can be stored in the integer variable, enabling the owner to set arbitrary balances through carefully crafted transactions that exploit this overflow condition.
The operational impact of this vulnerability extends beyond simple balance manipulation, creating a significant threat to the entire token ecosystem and user trust within the Nectar platform. An attacker with owner access can effectively drain the contract of all tokens by setting balances to maximum values, or conversely, can manipulate specific user accounts to gain unauthorized access to funds. This vulnerability directly impacts the fundamental principles of blockchain security and smart contract reliability, as it allows for unauthorized token distribution and potential financial loss for users who hold NCTR tokens. The implications are particularly severe because the vulnerability does not require external interaction from users; it only requires the owner of the contract to execute the malicious mintToken function, making it a critical flaw that undermines the entire security model of the token.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements in smart contract development practices. The primary fix involves implementing proper integer overflow protection through explicit bounds checking and validation before any arithmetic operations are performed within the mintToken function. This includes using safe math libraries such as OpenZeppelin's SafeMath or implementing explicit overflow checks using require statements that verify the result of arithmetic operations will not exceed maximum integer values. Organizations should also consider implementing additional access controls and audit mechanisms to monitor contract operations, as well as adopting comprehensive code review processes that specifically examine arithmetic operations and data type handling. The vulnerability demonstrates the critical importance of adhering to established security frameworks and best practices in smart contract development, including the principles outlined in the OWASP Smart Contract Security Verification Standard, which emphasizes the need for proper input validation and arithmetic operation safety to prevent similar vulnerabilities from occurring in future deployments.