CVE-2018-13583 in Shmoo
Summary
by MITRE
The mintToken function of a smart contract implementation for Shmoo, 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-2018-13583 represents a critical integer overflow flaw within the mintToken function of the Shmoo Ethereum token smart contract implementation. This vulnerability stems from improper input validation and arithmetic handling within the smart contract's codebase, creating a scenario where the contract owner can manipulate user balances arbitrarily. The flaw exists at the core of the token's issuance mechanism, where the mintToken function fails to properly validate or constrain the parameters passed to it, allowing for malicious manipulation of the token distribution system.
The technical exploitation of this vulnerability occurs through the manipulation of integer arithmetic operations within the smart contract's mintToken function. When the contract owner invokes this function with carefully crafted parameters, the integer overflow condition allows them to bypass normal balance limitations and set any user's token balance to an arbitrary value. This type of vulnerability is classified under CWE-190 as an integer overflow, specifically manifesting as an unsigned integer overflow that can be leveraged for privilege escalation within the token system. The vulnerability directly impacts the contract's integrity and the fundamental principles of token distribution and user account management.
The operational impact of this vulnerability extends beyond simple balance manipulation to compromise the entire token ecosystem's trust model and financial integrity. An attacker with access to the contract owner's private key can arbitrarily inflate or deflate user balances, potentially leading to massive financial losses for token holders and undermining the token's value proposition. The vulnerability enables scenarios such as creating unlimited tokens for specific users, effectively allowing the contract owner to mint tokens without proper authorization or accounting. This exploitation capability directly violates the decentralized and trustless principles that underpin blockchain-based token systems, as it allows a single entity to manipulate the token supply and user balances.
Mitigation strategies for this vulnerability require immediate contract redeployment with proper integer overflow protections and comprehensive input validation mechanisms. The recommended approach involves implementing explicit bounds checking and using safe arithmetic libraries that prevent integer overflow conditions. Additionally, the contract should enforce access controls and require multi-signature authorization for sensitive functions like mintToken. The vulnerability's remediation aligns with ATT&CK technique T1059.006 for command and scripting interpreter usage, as it involves exploiting the smart contract's execution environment through parameter manipulation. Security audits should also implement formal verification methods and static analysis tools to detect similar vulnerabilities in smart contract code, ensuring proper adherence to secure coding practices and preventing similar integer overflow scenarios in future implementations.