CVE-2018-13744 in Crowdnext
Summary
by MITRE
The mintToken function of a smart contract implementation for Crowdnext (CNX), 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-2018-13744 represents a critical integer overflow flaw within the mintToken function of the Crowdnext (CNX) Ethereum token smart contract. This vulnerability resides in the contract's token issuance mechanism where the owner can manipulate user balances through improper integer handling. The flaw allows an attacker with ownership privileges to arbitrarily set any user's token balance to any desired value, effectively enabling unauthorized token distribution or manipulation of the token economy. The vulnerability stems from the lack of proper input validation and overflow checks during arithmetic operations within the mintToken function, creating a scenario where mathematical operations can exceed the maximum representable value for the data type used.
The technical implementation of this vulnerability follows CWE-190, which specifically addresses integer overflow conditions where an attacker can cause a signed or unsigned integer to wrap around to an unintended value. In the context of Ethereum smart contracts, this typically occurs when operations involving uint256 or similar unsigned integer types exceed their maximum capacity of 2^256-1. The mintToken function likely performs arithmetic operations without proper bounds checking, allowing the owner to manipulate the balance calculation in such a way that the result overflows and produces an unexpected value. This vulnerability directly impacts the contract's integrity and the fundamental principle of decentralized trust, as it allows the contract owner to bypass normal token issuance rules and manipulate user holdings at will.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token ecosystem and user trust in the platform. An attacker with owner privileges could inflate user balances to create artificial scarcity, manipulate token distribution for personal gain, or even create a scenario where the total supply calculation becomes corrupted. The vulnerability affects all users whose balances could be manipulated through this function, potentially leading to financial losses and market instability. Additionally, since this involves the token owner's capabilities, it demonstrates a fundamental flaw in the contract's access control and privilege management, creating risks for token holders who may have trusted the contract's integrity. The vulnerability also creates potential for cascading effects where manipulated balances could impact other contract functions that depend on accurate token supply calculations.
Mitigation strategies for this vulnerability require immediate implementation of proper integer overflow protection mechanisms within the smart contract code. The recommended approach involves incorporating explicit bounds checking and overflow detection before any arithmetic operations in the mintToken function, utilizing Solidity's built-in overflow protection features or external libraries such as OpenZeppelin's SafeMath library. Contract owners should implement comprehensive input validation to ensure that balance calculations remain within acceptable ranges and that no integer overflow conditions can occur. Additionally, the contract should undergo thorough security auditing to identify and remediate similar vulnerabilities across all arithmetic operations. The vulnerability highlights the importance of following secure coding practices as outlined in the OWASP Smart Contract Security Verification Standard and should be addressed through proper code review processes that include automated static analysis tools. Regular security assessments and continuous monitoring of contract functions are essential to prevent similar issues from emerging in future contract updates or modifications.