CVE-2018-14006 in Neo Genesis Token
Summary
by MITRE
An integer overflow vulnerability exists in the function multipleTransfer of Neo Genesis Token (NGT), an Ethereum token smart contract. An attacker could use it to set any user's balance.
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Analysis
by VulDB Data Team • 03/04/2020
The integer overflow vulnerability in the Neo Genesis Token smart contract represents a critical security flaw that undermines the fundamental integrity of the token's balance management system. This vulnerability resides within the multipleTransfer function, which is designed to facilitate batch transfers of tokens between multiple recipients. The flaw stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types, creating a scenario where malicious actors can manipulate the contract's state through carefully crafted inputs. Such vulnerabilities are particularly dangerous in blockchain environments where financial assets are at stake and where the immutable nature of smart contracts means that once deployed, security flaws cannot be easily corrected without complete contract replacement.
The technical implementation of this vulnerability exploits the inherent limitations of fixed-width integer representations within the Ethereum Virtual Machine. When the multipleTransfer function processes multiple token transfers, it likely performs arithmetic operations that should validate against overflow conditions but fails to do so adequately. This allows an attacker to input values that, when processed through the contract's mathematical operations, result in integer overflow conditions that produce unexpected and exploitable outcomes. The vulnerability specifically enables an attacker to manipulate user balances by leveraging the overflow behavior to create unintended values that bypass normal balance validation checks. According to the CWE catalog, this corresponds to CWE-190, Integer Overflow or Wraparound, which is classified as a high-severity weakness due to its potential for causing system instability and unauthorized access to resources.
The operational impact of this vulnerability extends beyond simple balance manipulation to encompass potential financial loss and contract integrity compromise. An attacker who successfully exploits this vulnerability can set arbitrary balances for any user account within the token contract, effectively allowing them to create unlimited tokens or transfer tokens they shouldn't possess. This represents a complete breakdown of the token's access control mechanisms and trust model, as the attacker essentially gains the ability to modify the token distribution without authorization. The vulnerability's exploitation directly violates the principle of least privilege and can lead to significant financial damage, especially if the affected token has substantial value or if the attacker can leverage the compromised balances to execute additional attacks within the broader ecosystem. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be categorized under the T1068 privilege escalation tactic, where attackers leverage software vulnerabilities to gain unauthorized access to resources.
Mitigation strategies for this vulnerability require immediate attention through contract auditing and potential redeployment of secure versions. The most effective approach involves implementing proper integer overflow protections through explicit boundary checks and using safe arithmetic operations that prevent overflow conditions. Solidity developers should employ modern verification techniques and utilize libraries that provide overflow protection mechanisms such as OpenZeppelin's SafeMath library. Additionally, comprehensive testing including fuzzing and formal verification should be conducted to identify similar vulnerabilities within the contract's codebase. The vulnerability also underscores the importance of following secure coding practices for blockchain applications and adheres to the principle of defense in depth, where multiple layers of security controls are implemented to protect against various attack vectors. Organizations should implement continuous monitoring and regular security assessments to identify and remediate similar vulnerabilities in their smart contract deployments, as this type of flaw represents a common class of security issues that can be systematically addressed through proper development practices and security protocols.