CVE-2018-13553 in Micro BTC
Summary
by MITRE
The mintToken function of a smart contract implementation for Micro BTC (MBTC), 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-2018-13553 represents a critical integer overflow flaw within the mintToken function of the Micro BTC (MBTC) smart contract deployed on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic handling within the contract's code, specifically affecting how the contract processes token minting operations. The flaw allows the contract owner to manipulate user balances through a mathematical overflow condition that occurs when the contract attempts to increment token balances beyond their maximum representable values.
The technical implementation of this vulnerability manifests in the mintToken function where the smart contract fails to properly validate or constrain the parameters passed during token creation. When the owner invokes this function with maliciously crafted inputs, the integer overflow condition enables the manipulation of account balances to arbitrary values. This occurs because the contract does not implement proper bounds checking or overflow detection mechanisms that would normally prevent such mathematical anomalies. The vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented weakness in software systems where arithmetic operations exceed the maximum value that can be represented by the underlying data type.
The operational impact of this vulnerability extends beyond simple balance manipulation, creating a fundamental compromise of the token's integrity and the trust model that underpins the entire smart contract ecosystem. An attacker with owner privileges can effectively create unlimited tokens, manipulate user balances to zero, or inflate balances to maliciously high values, potentially disrupting the token's economic model and causing significant financial losses for users. The vulnerability also undermines the core principles of blockchain security by allowing unauthorized manipulation of the ledger state through legitimate contract owner functions. This type of flaw can be exploited to drain funds from user accounts or to create artificial scarcity in the token market, fundamentally breaking the trust assumptions that users place in smart contract systems.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and arithmetic boundary checks within the smart contract code. The most effective approach involves adding explicit overflow detection mechanisms using modern solidity practices such as require statements with mathematical bounds checking or utilizing libraries like OpenZeppelin's SafeMath implementation. The contract should validate that token minting operations do not result in values exceeding the maximum representable integer limits for the token's balance data types. Additionally, implementing proper access controls and audit trails can help detect unauthorized manipulations, while regular security audits and formal verification processes can identify similar vulnerabilities before they can be exploited. This vulnerability highlights the critical importance of adhering to secure coding practices in blockchain development environments and aligns with ATT&CK technique T1548.001 for privilege escalation through smart contract manipulation, emphasizing the need for comprehensive security measures in decentralized applications.