CVE-2018-13545 in HashShield
Summary
by MITRE
The mintToken function of a smart contract implementation for HashShield, 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-2018-13545 represents a critical integer overflow flaw within the mintToken function of the HashShield Ethereum token smart contract implementation. This vulnerability resides in the core token minting mechanism that allows contract owners to create new tokens and distribute them to users. The flaw manifests when the mintToken function processes token minting operations without proper input validation or overflow checking, creating a scenario where arithmetic operations can exceed the maximum value that can be represented by the underlying data type. The integer overflow occurs during the balance update process when the contract attempts to increment a user's token balance, potentially causing the value to wrap around to an unexpected lower value. This vulnerability directly impacts the contract's integrity and can be exploited to manipulate user balances in unintended ways.
The technical execution of this vulnerability follows a well-established pattern that aligns with CWE-190, which specifically addresses integer overflow and unsigned integer overflow conditions. An attacker with owner privileges can leverage this flaw to manipulate the mintToken function by providing carefully crafted parameters that cause the balance arithmetic to overflow. When the overflow occurs, the system's internal accounting becomes corrupted, allowing the attacker to set any user's balance to an arbitrary value. The operational impact extends beyond simple balance manipulation as it fundamentally undermines the trust model of the token system. This vulnerability can be exploited to create unlimited tokens or to manipulate balances to achieve unauthorized access to token resources, potentially leading to financial loss for other users and complete compromise of the token's economic model.
The security implications of CVE-2018-13545 align with ATT&CK technique T1059.006, which involves the use of smart contracts to execute malicious code through vulnerabilities in their implementation. The vulnerability enables privilege escalation attacks where the contract owner can exploit the integer overflow to gain unauthorized control over user balances and token distribution. This flaw creates an attack surface that allows for manipulation of the token economy, potentially enabling the attacker to drain funds from other users or create artificial scarcity. The impact on the token ecosystem extends to potential loss of user trust, regulatory concerns, and financial losses for token holders. The vulnerability demonstrates a fundamental lack of input validation and proper arithmetic boundary checking that is essential in smart contract development, as outlined in industry best practices for blockchain security.
Mitigation strategies for this vulnerability require immediate contract redeployment with proper integer overflow protection mechanisms. The implementation must incorporate comprehensive input validation, explicit overflow checks, and use of secure arithmetic libraries such as OpenZeppelin's SafeMath. Additionally, the contract owner should implement proper access controls and audit logging to detect unauthorized operations. Regular security audits and formal verification of smart contract code are essential preventive measures that align with security frameworks like the Ethereum Smart Contract Security Best Practices. The vulnerability also highlights the importance of thorough code review processes and the adoption of security-focused development methodologies that incorporate automated testing and static analysis tools to identify similar flaws before deployment to the mainnet.