CVE-2018-17050 in PolyAI
Summary
by MITRE
The mintToken function of a smart contract implementation for PolyAi (AI), 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 • 03/26/2020
The vulnerability identified in CVE-2018-17050 represents a critical integer overflow flaw within the mintToken function of the PolyAi (AI) Ethereum token smart contract implementation. This vulnerability stems from improper input validation and arithmetic handling within the smart contract code, specifically affecting the token's issuance mechanism. The flaw allows an attacker with owner privileges to manipulate token balances by setting arbitrary values for user accounts, fundamentally compromising the integrity of the token economy. Such a vulnerability directly impacts the fundamental principles of blockchain-based token systems where transparent and immutable balance tracking is essential for trust and security.
The technical exploitation of this integer overflow occurs when the mintToken function processes token minting operations without proper bounds checking on the values being assigned to user balances. In Ethereum smart contracts, integer overflows can be leveraged to bypass normal arithmetic constraints and manipulate state variables in unexpected ways. When an attacker invokes the mintToken function with carefully crafted parameters, the overflow condition allows them to write values beyond the normal range of the data type used for balance storage, potentially enabling the assignment of extremely large or negative values to user accounts. This flaw falls under the CWE-190 category of integer overflow and under CWE-682 of incorrect arithmetic, both of which are well-documented weaknesses in software systems that directly translate to smart contract vulnerabilities.
The operational impact of this vulnerability extends beyond simple balance manipulation, as it fundamentally undermines the security model of the PolyAi token system. An attacker with owner access can arbitrarily inflate or deflate user balances, potentially leading to massive economic disruption within the token ecosystem. The vulnerability creates opportunities for financial gain through manipulation of token distributions, could enable the creation of unlimited tokens, and may allow attackers to bypass normal token transfer restrictions. From an attacker's perspective, this represents a high-value exploit as it provides complete control over user balances without requiring additional privileges or complex attack chains. The vulnerability aligns with ATT&CK technique T1548.001 (Abuse Elevation Control Mechanism) where the attacker leverages existing owner privileges to escalate their control within the system.
Mitigation strategies for this vulnerability require immediate code review and implementation of proper input validation mechanisms within the smart contract. The fix involves implementing bounds checking on all balance assignments and ensuring that arithmetic operations within the mintToken function properly handle potential overflow conditions through the use of SafeMath libraries or similar defensive programming techniques. Additionally, the contract should implement proper access controls and audit logging to track all minting operations and balance modifications. Regular security audits and formal verification of smart contract code should be implemented to prevent similar vulnerabilities from being introduced in future updates. The vulnerability highlights the importance of rigorous testing and code review processes specifically tailored for blockchain environments where a single flaw can result in complete system compromise. Organizations should also implement multi-signature ownership models and time-locks for critical operations to reduce the risk of unauthorized exploitation.