CVE-2018-13172 in bzxcoin
Summary
by MITRE
The mintToken function of a smart contract implementation for bzxcoin (BZX), 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 • 02/25/2020
The vulnerability identified as CVE-2018-13172 resides within the mintToken function of bzxcoin (BZX) smart contract implementation on the Ethereum blockchain. This flaw represents a critical integer overflow vulnerability that fundamentally compromises the contract's tokenomics and financial integrity. The vulnerability allows the contract owner to manipulate user balances arbitrarily, creating a severe security risk that extends beyond simple financial loss to encompass potential systemic threats within the token ecosystem.
The technical implementation of this vulnerability stems from improper input validation and arithmetic operations within the mintToken function. When the contract processes token minting operations, it fails to properly validate the parameters passed to the function, particularly regarding the amount parameter that determines how many tokens to mint for a specific user. This lack of proper bounds checking enables an attacker with owner privileges to craft malicious inputs that cause integer overflow conditions, effectively bypassing normal token balance limitations. The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions, and demonstrates how insufficient input sanitization can lead to severe financial consequences in smart contract environments.
The operational impact of this vulnerability extends far beyond immediate financial manipulation, creating cascading effects throughout the token's ecosystem and potentially affecting related smart contracts. An attacker with owner access can arbitrarily inflate or deflate user balances, manipulate token distribution, and potentially exploit this capability to create artificial market conditions or gain unfair advantages in token-based systems. The vulnerability is particularly dangerous because it operates at the core level of token management, affecting the fundamental trust model that underpins cryptocurrency systems. This capability allows for unauthorized wealth redistribution and can undermine the entire economic framework of the bzxcoin token, potentially leading to loss of investor confidence and market instability.
Mitigation strategies for this vulnerability require immediate attention through contract upgrades and comprehensive security audits. The most effective approach involves implementing proper input validation, utilizing safe arithmetic libraries, and conducting thorough parameter checking before any balance modifications occur. Additionally, the contract should enforce proper access controls and implement multi-signature requirements for critical functions to reduce the risk of unauthorized access. Security practitioners should also consider implementing event logging for all mintToken operations to enable detection of suspicious activities and maintain audit trails. The vulnerability demonstrates the critical importance of adhering to secure coding practices in blockchain environments and highlights the need for comprehensive testing including boundary condition analysis and formal verification methods to prevent similar issues in future smart contract deployments. Organizations should also implement continuous monitoring systems to detect anomalous behavior patterns that might indicate exploitation attempts.