CVE-2018-13192 in Jobscoin
Summary
by MITRE
The mintToken function of a smart contract implementation for Jobscoin (JOB), 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 • 02/25/2020
The CVE-2018-13192 vulnerability represents a critical integer overflow flaw within the mintToken function of Jobscoin (JOB) smart contract implementation on the Ethereum blockchain. This vulnerability stems from improper input validation and arithmetic operations that fail to account for the maximum limits of integer data types. The flaw specifically affects the token contract's ability to safely handle large numerical values during balance modifications, creating a scenario where an attacker can manipulate the contract's state through crafted transactions. The vulnerability's severity is amplified by its location within a core function responsible for token creation and distribution, making it particularly dangerous for the overall integrity of the token economy.
The technical exploitation of this integer overflow occurs when the mintToken function processes user balance updates without proper boundary checks or overflow protection mechanisms. When an attacker provides input values that exceed the maximum representable value for the integer type being used, the arithmetic operation wraps around to a much smaller value due to the underlying binary representation. This behavior creates a predictable pattern where the contract's internal accounting becomes corrupted, allowing the contract owner to manipulate user balances to arbitrary values. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, specifically manifesting as an unsigned integer overflow in the context of blockchain smart contracts where financial state management is paramount.
Operationally, this vulnerability presents significant risks to both the Jobscoin ecosystem and its users. An attacker with access to the contract owner privileges can manipulate user balances to create unlimited tokens, effectively enabling unauthorized minting of new JOB tokens. The impact extends beyond simple balance manipulation as it can lead to total loss of funds for users, potential market manipulation through artificial token distribution, and complete compromise of the token's economic model. The vulnerability allows for scenarios where an attacker could set user balances to negative values or extremely large positive values, potentially causing the contract to behave unpredictably or even become permanently unusable. This type of flaw directly violates the fundamental principles of blockchain security where deterministic and predictable state transitions are essential for trustless systems.
The mitigation strategies for CVE-2018-13192 involve implementing comprehensive input validation and arithmetic operation safeguards within the smart contract code. Developers should utilize safe math libraries that include overflow checks before performing arithmetic operations, ensuring that all integer operations within the mintToken function are protected against boundary conditions. The contract should also implement proper access controls and audit mechanisms to monitor for unauthorized balance modifications. Additionally, regular security audits and formal verification processes should be conducted to identify similar vulnerabilities across the entire smart contract codebase. This vulnerability aligns with ATT&CK technique T1548.001 related to privilege escalation through smart contract manipulation, highlighting the need for robust contract governance and security practices in decentralized applications. The remediation process requires immediate code review and deployment of patched versions while potentially implementing emergency measures to freeze token transfers until the vulnerability is fully addressed.