CVE-2018-13219 in YourCoin
Summary
by MITRE
The sell function of a smart contract implementation for YourCoin (ICO) (Contract Name: ETH033), an Ethereum token, has an integer overflow in which "amount * sellPrice" can be zero, consequently reducing a seller's assets.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 02/25/2020
The vulnerability identified in CVE-2018-13219 affects the ETH033 smart contract implementation for the YourCoin ICO token on the Ethereum blockchain. This represents a critical integer overflow flaw that fundamentally compromises the contract's financial integrity and asset management capabilities. The vulnerability specifically resides within the sell function of the smart contract, where mathematical operations involving token amounts and sell prices can produce unexpected results due to improper overflow handling. The flaw manifests when the multiplication operation "amount * sellPrice" evaluates to zero, which directly impacts the seller's asset balance in an unintended manner. This type of vulnerability falls under the CWE-191 category of Integer Underflow/Overflow, specifically representing an integer overflow condition that can lead to incorrect arithmetic operations and financial loss.
The technical implementation of this vulnerability stems from the lack of proper input validation and overflow checking within the sell function's mathematical operations. When a seller attempts to redeem tokens, the smart contract performs a multiplication between the token amount being sold and the current sell price to determine the value of the transaction. If either the amount or sell price is zero, or if the multiplication results in an overflow that wraps around to zero due to insufficient bit width handling, the system incorrectly processes the transaction. This can result in sellers receiving zero value for their tokens or having their token balances reduced without proper compensation. The vulnerability demonstrates a fundamental flaw in the contract's mathematical processing logic and highlights the importance of implementing comprehensive overflow protection mechanisms in smart contract development.
The operational impact of this vulnerability extends beyond simple financial loss to encompass broader security implications for the entire token ecosystem. Users who attempt to sell their tokens may find their assets mysteriously reduced or their transactions processed at zero value, leading to significant financial losses and eroding trust in the platform. The vulnerability creates a potential attack vector where malicious actors could exploit the integer overflow to manipulate token balances or create artificial market conditions. Smart contract security researchers have noted that such flaws often compound when multiple operations depend on the same vulnerable mathematical functions, potentially leading to cascading failures in the contract's financial logic. The impact is particularly severe in ICO environments where user trust and financial security are paramount, as this vulnerability directly affects the core functionality of token redemption and asset management.
Mitigation strategies for this vulnerability require immediate implementation of comprehensive overflow protection measures within the smart contract code. Developers should implement explicit overflow checks using require statements or SafeMath libraries to prevent mathematical operations from producing unexpected results. The contract should validate all input parameters before performing arithmetic operations and ensure that multiplication results remain within acceptable numerical bounds. Additionally, the sell function should include proper error handling and logging mechanisms to detect and report anomalous transactions. Organizations should conduct thorough security audits of all smart contract implementations and implement continuous monitoring systems to detect potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1583.001 related to acquisition of resources, as it represents a critical weakness that adversaries could exploit to compromise user assets. The fix should also include comprehensive testing with edge cases including zero values, maximum integer values, and boundary conditions to ensure robust protection against similar vulnerabilities in future implementations.