CVE-2018-13233 in GSI
Summary
by MITRE
The sell function of a smart contract implementation for GSI, an Ethereum token, has an integer overflow in which "amount * sellPrice" can be zero, consequently reducing a seller's assets.
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Analysis
by VulDB Data Team • 02/25/2020
The vulnerability identified in CVE-2018-13233 represents a critical integer overflow flaw within the sell function of a smart contract implementation for GSI tokens operating on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operation handling within the contract's codebase, creating a scenario where mathematical operations can produce unexpected results due to the limited range of integer data types. The specific issue occurs when the contract attempts to calculate "amount * sellPrice" during token sales, where the multiplication operation can result in an overflow condition that manifests as a zero value.
The technical implementation of this vulnerability demonstrates a classic example of insufficient integer overflow protection in smart contract development practices. When the sell function processes token redemption requests, it performs arithmetic operations without adequate bounds checking or overflow detection mechanisms. The vulnerability specifically manifests when the product of the token amount and the sell price exceeds the maximum value that can be represented by the integer data type used in the contract, causing the result to wrap around to zero or another unintended value. This behavior violates the fundamental principles of secure smart contract development and represents a direct violation of CWE-190, which addresses integer overflow and underflow conditions.
The operational impact of this vulnerability extends beyond simple financial loss, creating a significant risk to the integrity and security of the entire token ecosystem. When a seller attempts to redeem tokens through the compromised sell function, the zero result from the faulty multiplication operation effectively nullifies the transaction's intended outcome, allowing attackers to manipulate their asset balances without proper authorization. This creates a scenario where malicious actors can potentially drain funds or manipulate token distributions, undermining the trust and reliability of the token system. The vulnerability also exposes the contract to potential reentrancy attacks and other exploitation vectors that leverage the predictable behavior of overflow conditions.
From a cybersecurity perspective, this vulnerability aligns with several ATT&CK framework techniques including TA0004 Privilege Escalation and TA0005 Defense Evasion, as it allows unauthorized manipulation of contract state and potentially enables attackers to bypass normal transaction validation processes. The flaw represents a fundamental lack of input sanitization and mathematical operation validation that should be standard practice in smart contract development. Organizations implementing similar token contracts should conduct comprehensive security audits and implement proper integer overflow protection mechanisms such as using libraries like OpenZeppelin's SafeMath or implementing explicit bounds checking before arithmetic operations. The vulnerability also highlights the importance of formal verification and thorough testing of smart contract code before deployment, particularly in financial applications where such flaws can result in substantial monetary losses and system compromise.