CVE-2018-13635 in HBcms
Summary
by MITRE
The mintToken function of a smart contract implementation for HBCM, 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-2018-13635 represents a critical integer overflow flaw within the mintToken function of the HBCM Ethereum token smart contract implementation. This vulnerability resides in the core tokenomics functionality where the contract owner can manipulate user balances through improper integer handling. The flaw allows for arbitrary balance manipulation by exploiting unchecked arithmetic operations that fail to validate input parameters before performing mathematical calculations. The mintToken function serves as a mechanism for creating new tokens and assigning them to user addresses, but due to the integer overflow condition, it becomes a vector for unauthorized balance manipulation.
The technical execution of this vulnerability stems from the absence of proper input validation and overflow checking within the smart contract code. When the mintToken function processes token minting operations, it performs arithmetic calculations without verifying whether the resulting values exceed the maximum limits of the integer data types used. This creates a scenario where an attacker with owner privileges can manipulate the token supply and user balances by exploiting the overflow behavior to create unintended values. The vulnerability manifests as an integer overflow condition that allows for values to wrap around to unexpected states, enabling the contract owner to set arbitrary user balances to any desired amount. This type of vulnerability is classified under CWE-190 as an integer overflow or wraparound error, which represents a fundamental weakness in arithmetic operation handling within software systems.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token economy and user trust within the HBCM ecosystem. An attacker with access to the contract owner privileges can arbitrarily inflate user balances, create artificial wealth distribution, or even drain the token supply through strategic manipulation of the minting process. The vulnerability directly affects the token's integrity and can lead to significant financial losses for users and the project itself. The implications include potential market manipulation, loss of confidence in the token's value, and possible regulatory scrutiny due to the unauthorized alteration of token distributions. This vulnerability undermines the fundamental principles of blockchain security and smart contract reliability, as it allows for privileged account manipulation that should not be possible within a properly secured system.
Mitigation strategies for this vulnerability require immediate code review and patching of the affected smart contract implementation. The fix must implement proper input validation and integer overflow checking before any arithmetic operations occur within the mintToken function. This includes verifying that calculated values remain within acceptable ranges and implementing bounds checking for all user-supplied parameters. Additionally, the contract should incorporate comprehensive testing procedures including fuzz testing and formal verification to identify similar vulnerabilities in other functions. The remediation process must also consider implementing access controls and audit trails to monitor any balance modifications and ensure that only legitimate minting operations occur. Organizations should follow established security frameworks such as the OWASP Smart Contract Security Verification Standard and apply defensive programming practices to prevent similar issues in future implementations. The vulnerability highlights the critical need for robust smart contract auditing and adherence to security best practices in blockchain development environments.