CVE-2018-18667 in Pylon
Summary
by MITRE
The mintToken function of Pylon (PYLNT) aka PylonToken, 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, a related issue to CVE-2018-11812.
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Analysis
by VulDB Data Team • 04/24/2020
The CVE-2018-18667 vulnerability affects the Pylon (PYLNT) token smart contract on the Ethereum blockchain, representing a critical integer overflow flaw that fundamentally compromises the token's security model. This vulnerability exists within the mintToken function, which is designed to create new tokens and distribute them to users. The flaw arises from improper input validation and arithmetic operations that fail to check for overflow conditions, creating a pathway for malicious actors to manipulate token balances. The vulnerability is particularly concerning as it allows the contract owner to arbitrarily set any user's balance to any desired value, effectively enabling unlimited token creation and distribution manipulation.
The technical implementation of this vulnerability stems from the absence of proper overflow checks in the mintToken function, which operates on unsigned integer values without adequate bounds verification. When the contract attempts to increment token balances or perform arithmetic operations on token amounts, the lack of overflow protection causes the values to wrap around to unexpected states. This behavior aligns with CWE-191, which describes integer underflow/overflow vulnerabilities where arithmetic operations produce results that exceed the maximum or minimum representable values. The flaw directly enables privilege escalation attacks where the contract owner can manipulate token distributions without restriction, potentially leading to complete control over the token supply and user balances.
The operational impact of this vulnerability extends far beyond simple balance manipulation, creating cascading security risks that affect the entire token ecosystem. An attacker with access to the owner account can effectively drain or inflate token supplies, manipulate trading dynamics, and compromise the integrity of any token-based applications that depend on Pylon's balance data. The vulnerability's relationship to CVE-2018-11812 demonstrates a pattern of similar flaws in token contracts, suggesting that multiple instances of this class of vulnerability may exist within the broader Ethereum token ecosystem. This creates a significant risk for users who hold PYLNT tokens, as the value of their holdings becomes potentially unstable due to the contract's inability to maintain accurate balance accounting.
Mitigation strategies for CVE-2018-18667 require immediate contract upgrades with proper overflow protection mechanisms and comprehensive security audits. The recommended approach involves implementing safe math libraries that automatically check for overflow conditions before performing arithmetic operations, as well as conducting thorough code reviews to identify similar vulnerabilities in other contract functions. Organizations should also implement proper access controls and consider multi-signature wallets for contract ownership to reduce the risk of unauthorized access. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and resource consumption attacks, where adversaries leverage contract-level flaws to manipulate token distributions and potentially disrupt token-based services. The vulnerability highlights the critical importance of formal verification and security testing in smart contract development, particularly for functions that handle token creation and balance modifications.