CVE-2018-13559 in UTCT
Summary
by MITRE
The mintToken function of a smart contract implementation for UTCT, 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-2018-13559 represents a critical integer overflow flaw within the mintToken function of a UTCT Ethereum token smart contract implementation. This vulnerability falls under the CWE-190 category of integer overflow and under the ATT&CK technique T1059.006 for execution through smart contracts. The flaw stems from improper input validation and arithmetic operations within the token minting mechanism that fails to properly check for overflow conditions during balance updates. When the mintToken function processes token creation requests, it performs arithmetic operations without adequate bounds checking, creating an environment where malicious actors can manipulate the contract's internal state.
The technical exploitation of this vulnerability occurs when an attacker with owner privileges manipulates the mintToken function to increment token balances beyond the maximum representable value for the data type used in the contract. This overflow condition allows the attacker to effectively bypass normal balance limitations and set arbitrary user balances to any desired value, including potentially infinite amounts. The vulnerability is particularly dangerous because it operates at the contract level, where the owner privileges are typically limited to authorized parties, making the attack vector both subtle and potentially devastating. The integer overflow manifests when the contract attempts to add new tokens to existing balances without proper overflow detection mechanisms.
Operationally, this vulnerability creates significant risks for token holders and the broader ecosystem relying on the UTCT token implementation. The ability to set arbitrary balances means that an attacker could potentially drain the entire token supply or manipulate market dynamics by creating artificial wealth for specific addresses. The impact extends beyond immediate financial loss to include potential disruption of token economics, loss of trust in the platform, and possible regulatory implications. The vulnerability affects not only the direct token holders but also the underlying blockchain network by potentially causing transaction failures or requiring emergency contract upgrades to address the exploit.
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 before any arithmetic operations, utilizing safe math libraries such as OpenZeppelin's SafeMath implementation, and ensuring all balance updates undergo proper validation. Additionally, contract owners should implement comprehensive testing procedures including fuzz testing and formal verification to identify similar vulnerabilities. The fix should also include proper access control mechanisms and audit trails to monitor any unauthorized balance modifications. Security audits should be conducted regularly to ensure that similar integer overflow vulnerabilities do not exist in other contract functions, and the implementation should follow established best practices for smart contract security as outlined in the Ethereum Smart Contract Security Best Practices framework.