CVE-2018-13535 in PACCOIN
Summary
by MITRE
The mintToken function of a smart contract implementation for PACCOIN, 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 • 02/27/2020
The vulnerability identified as CVE-2018-13535 resides within the mintToken function of a smart contract implementation for PACCOIN, an Ethereum-based token. This flaw represents a critical integer overflow vulnerability that fundamentally compromises the contract's integrity and security model. The vulnerability manifests when the mintToken function processes token minting operations without proper overflow checks, allowing malicious actors to manipulate the token supply mechanism. The integer overflow occurs during arithmetic operations involving token balances, where calculations exceed the maximum representable value for the data type used, causing the value to wrap around and produce unexpected results.
The technical implementation of this vulnerability stems from inadequate input validation and arithmetic boundary checking within the smart contract's mintToken function. When the contract owner invokes this function, the system fails to validate whether the resulting token balance would exceed the maximum value that can be stored in the designated data type. This oversight creates a scenario where an attacker can manipulate the minting process to set arbitrary user balances to any desired value, effectively bypassing the normal token distribution and accounting mechanisms. The vulnerability directly maps to CWE-190, which identifies integer overflow and underflow issues, and specifically relates to CWE-682, which covers incorrect implementation of arithmetic operations. The flaw demonstrates a fundamental lack of proper bounds checking that is essential in blockchain smart contracts where financial assets are at stake.
The operational impact of this vulnerability is severe and multifaceted, potentially enabling unlimited token generation and unauthorized balance manipulation. An attacker with access to the contract owner privileges can exploit this vulnerability to inflate token supplies beyond intended limits, effectively causing a form of inflation that devalues the token for legitimate holders. Additionally, the ability to set arbitrary user balances opens pathways for targeted manipulation of specific accounts, potentially enabling theft of funds or disruption of token distribution mechanisms. This vulnerability undermines the core trust assumptions of the token ecosystem, as it allows for the creation of tokens without proper authorization or accounting. The implications extend beyond simple financial loss, as this flaw can compromise the entire token economy and potentially affect other contracts that interact with PACCOIN tokens.
Mitigation strategies for CVE-2018-13535 require immediate implementation of comprehensive input validation and arithmetic boundary checking within the smart contract code. The most effective approach involves adding explicit overflow checks using modern solidity practices such as require statements with appropriate conditions to validate that arithmetic operations remain within acceptable bounds. The contract should implement proper uint256 type validation and utilize safe math libraries that automatically handle overflow conditions. Additionally, implementing proper access control mechanisms and audit trails can help detect unauthorized minting operations. Organizations should consider deploying the contract with proper initialization values and ensuring that all arithmetic operations include appropriate bounds checking. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and resource consumption, as it allows attackers to manipulate token balances and potentially gain unauthorized access to resources. The remediation process should also include comprehensive code reviews and security testing to identify similar patterns in other contract functions that might be susceptible to the same class of vulnerabilities.