CVE-2018-13186 in MMTCoin
Summary
by MITRE
The mintToken function of a smart contract implementation for MMTCoin (MMT), 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-2018-13186 resides within the mintToken function of MMTCoin's smart contract implementation on the Ethereum blockchain. This flaw represents a critical integer overflow condition that fundamentally compromises the contract's integrity and security model. The vulnerability stems from inadequate input validation and overflow protection mechanisms within the token minting process, creating a scenario where the contract owner can manipulate user balances arbitrarily. The integer overflow occurs when the contract attempts to increment token balances without proper bounds checking, allowing malicious actors with ownership privileges to exploit the mathematical limitations of fixed-size integer variables.
The technical exploitation of this vulnerability enables the contract owner to manipulate user balances to any desired value, including potentially infinite amounts or negative balances. This represents a severe deviation from expected tokenomics and undermines the fundamental trust model of the cryptocurrency system. The flaw operates at the core of the contract's state management, where balance updates are not properly validated against overflow conditions. When the mintToken function processes token creation requests, it fails to implement proper overflow detection mechanisms that would normally prevent integer arithmetic from wrapping around to invalid values, creating a path for arbitrary balance manipulation.
The operational impact of this vulnerability extends beyond simple financial loss to encompass complete contract compromise and potential systemic risks within the Ethereum ecosystem. An attacker with access to the contract owner account can effectively control the distribution and value of MMTCoin tokens, potentially leading to market manipulation, complete loss of user funds, and undermining confidence in the token's legitimacy. The vulnerability affects all users of the MMTCoin token since any user's balance can be arbitrarily modified, creating a cascading effect that could destabilize trading pairs and market value. This type of vulnerability directly impacts the security posture of decentralized applications and demonstrates the critical importance of proper integer handling in smart contract development.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements. The primary fix involves implementing comprehensive overflow protection mechanisms using require statements or SafeMath libraries that prevent integer arithmetic from exceeding maximum values. Contract developers should enforce strict input validation on all balance modification functions and implement proper bounds checking before any arithmetic operations. Additionally, the contract owner should consider implementing multi-signature controls and regular security audits to prevent unauthorized access to privileged functions. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and represents a direct threat to the principles outlined in the Ethereum Smart Contract Security Best Practices. The ATT&CK framework categorizes this as a privilege escalation technique where an attacker leverages existing ownership rights to manipulate system state, making it particularly dangerous in permissioned environments where owner privileges are centralized.