CVE-2018-13746 in kBit
Summary
by MITRE
The mintToken function of a smart contract implementation for kBit, 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 • 03/03/2020
The vulnerability identified in CVE-2018-13746 represents a critical integer overflow flaw within the mintToken function of the kBit Ethereum token smart contract implementation. This vulnerability stems from inadequate input validation and arithmetic operation handling within the contract's codebase, creating a scenario where the contract owner can manipulate user balances arbitrarily. The flaw exists at the core level of the token's functionality, specifically when processing token minting operations that involve mathematical calculations with user-supplied values.
The technical execution of this vulnerability relies on the manipulation of integer arithmetic operations that exceed the maximum value that can be represented within the contract's data types. When the mintToken function processes token creation requests, it fails to properly validate or constrain the input parameters, particularly those related to balance adjustments and token amounts. This creates an overflow condition where the mathematical operation wraps around to produce unexpected results, allowing the contract owner to bypass normal balance limitations and directly set any user's token balance to an arbitrary value. The vulnerability operates under CWE-191, which specifically addresses integer underflow and overflow conditions, and aligns with ATT&CK technique T1059.001 for operating system command and scripting language invocation.
The operational impact of this vulnerability is severe and multifaceted, affecting both the integrity and security of the entire token ecosystem. Contract owners can exploit this flaw to artificially inflate user balances, potentially creating massive supply inflation or enabling unauthorized access to funds. The vulnerability undermines the fundamental trust model of the token system, as users cannot rely on accurate balance reporting or predictable token economics. Additionally, this flaw could enable financial loss for users who hold tokens, as attackers could manipulate their balances to zero or other unintended values, effectively stealing or destroying their assets. The vulnerability also impacts the contract's overall security posture by creating a backdoor that allows privileged access to user accounts without proper authorization mechanisms.
Mitigation strategies for CVE-2018-13746 require immediate implementation of comprehensive input validation and arithmetic operation safeguards within the smart contract code. Developers should implement explicit bounds checking and overflow protection mechanisms using modern Solidity practices such as SafeMath libraries or compiler versions that include built-in overflow protection. The contract owner must also establish proper access controls and audit procedures to prevent unauthorized exploitation of privileged functions. Additionally, regular security audits and formal verification processes should be implemented to identify similar vulnerabilities in the codebase. Organizations should consider redeploying the contract with proper overflow protection measures and potentially implementing a token recovery mechanism to address any damage already caused by the vulnerability. The remediation process should also include thorough testing of all arithmetic operations and balance modifications to ensure that no similar integer overflow conditions exist within the contract's functionality, as outlined in the ATT&CK framework's defensive strategies for smart contract security.