CVE-2018-13683 in exsulcoin
Summary
by MITRE
The mintToken function of a smart contract implementation for exsulcoin, 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 • 02/28/2020
The mintToken function in the exsulcoin Ethereum token smart contract contains a critical integer overflow vulnerability that fundamentally compromises the contract's integrity and user asset security. This vulnerability exists within the token's core functionality where the owner can manipulate user balances through improper integer handling during token creation processes. The flaw allows an attacker with contract ownership privileges to arbitrarily set any user's token balance to an arbitrary value, potentially enabling unlimited token generation or balance manipulation that directly impacts the token's economic model and user trust.
The technical implementation of this vulnerability stems from insufficient input validation and unchecked arithmetic operations within the mintToken function. When processing token minting requests, the smart contract fails to properly validate or constrain integer values, allowing for overflow conditions that can result in unexpected behavior. This vulnerability directly maps to CWE-190, which describes integer overflow and underflow conditions, and represents a classic example of improper handling of numeric data types in blockchain smart contracts. The absence of proper bounds checking and overflow protection mechanisms creates a scenario where mathematical operations can exceed the maximum representable value for the data type, leading to unpredictable balance manipulations.
The operational impact of this vulnerability extends beyond simple balance manipulation to potentially compromise the entire token ecosystem. An attacker with ownership privileges can create unlimited tokens, manipulate user balances to zero, or set balances to extremely high values that could disrupt the token's supply mechanism. This vulnerability undermines the fundamental principles of blockchain security and trustless systems, as it allows for arbitrary control over user assets without proper authorization. The implications are particularly severe for token holders who may lose their assets or see their holdings manipulated without any recourse, directly affecting the token's utility and market confidence.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The smart contract implementation should incorporate comprehensive input validation, proper integer overflow protection through library functions like OpenZeppelin's SafeMath, and thorough testing of all arithmetic operations. Additionally, contract ownership should be transferred to multi-signature wallets or decentralized governance mechanisms to prevent single points of failure. Security audits should be conducted using formal verification methods and static analysis tools to identify similar vulnerabilities across the entire contract codebase. This vulnerability exemplifies the importance of following secure coding practices in blockchain environments and aligns with ATT&CK technique T1059.001 for executing malicious code through smart contract manipulation, emphasizing the critical need for robust security controls in decentralized applications.