CVE-2018-13639 in Virtual Energy Units
Summary
by MITRE
The mintToken function of a smart contract implementation for Virtual Energy Units (VEU) (Contract Name: VEU_TokenERC20), 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 as CVE-2018-13639 resides within the mintToken function of the Virtual Energy Units (VEU) token smart contract implementation on the Ethereum blockchain. This contract, formally named VEU_TokenERC20, implements an ERC20 token standard that governs the creation and distribution of Virtual Energy Units. The flaw manifests as an integer overflow condition that fundamentally compromises the contract's ability to maintain accurate account balances and secure token distribution mechanisms. The vulnerability's severity stems from the fact that it directly affects the core tokenomics of the system, enabling unauthorized manipulation of user balances through the contract owner's privileged position.
The technical implementation of this vulnerability occurs within the mintToken function where integer overflow conditions are not properly validated or handled. When the contract owner invokes this function, they can manipulate the token minting process to set arbitrary user balances to any desired value. This occurs because the smart contract fails to implement proper bounds checking on the integer values used for balance calculations and token issuance. The overflow condition allows attackers to bypass normal token distribution limits and potentially create unlimited tokens or manipulate existing balances in ways that violate the expected token economics. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses issues where integer arithmetic operations produce results that exceed the maximum value representable by the data type.
The operational impact of this vulnerability extends far beyond simple balance manipulation, creating significant risks for both individual users and the overall token ecosystem. An attacker with owner privileges can arbitrarily inflate or deflate user balances, potentially leading to substantial financial losses for token holders and undermining the trust in the entire token system. The vulnerability also compromises the integrity of the token's supply mechanism, allowing for potential creation of unlimited tokens or manipulation of the total supply. This attack vector represents a critical weakness in the contract's access control and validation mechanisms, as it allows privilege escalation through the owner account to manipulate core token functions. The implications for token governance and user confidence are severe, as users cannot trust that their balances remain accurate or that the token distribution remains fair and transparent.
Mitigation strategies for this vulnerability require immediate implementation of comprehensive input validation and integer overflow protection measures within the smart contract code. The contract owner must implement proper bounds checking on all integer operations, particularly within the mintToken function, to prevent overflow conditions from occurring. This includes utilizing safe math libraries or implementing explicit overflow detection mechanisms that reject operations resulting in values exceeding the maximum representable integer limits. Additionally, the contract should enforce strict access controls and audit all owner operations to prevent unauthorized balance manipulation. The implementation should follow established security best practices for smart contract development and incorporate regular security audits to identify and remediate similar vulnerabilities. Organizations should also consider implementing multi-signature ownership controls and time locks for critical operations to reduce the risk of exploitation. The vulnerability demonstrates the critical importance of proper integer handling in blockchain smart contracts and aligns with ATT&CK technique T1548.001 for privilege escalation through smart contract manipulation, emphasizing the need for robust access control and validation mechanisms in decentralized applications.