CVE-2018-13648 in BGC
Summary
by MITRE
The mintToken function of a smart contract implementation for BGC, 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.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 02/28/2020
The vulnerability identified in CVE-2018-13648 represents a critical integer overflow flaw within the mintToken function of a BGC Ethereum token smart contract implementation. This vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which occurs when a program performs arithmetic operations on integer values that exceed the maximum representable value for the data type. The specific implementation flaw allows the contract owner to manipulate token balances through an unchecked arithmetic operation that can result in unexpected behavior due to the wraparound nature of integer arithmetic.
The technical exploitation of this vulnerability stems from the lack of proper input validation and overflow checking within the mintToken function. When the contract owner invokes this function, they can manipulate the token minting process to create arbitrary token balances for any user address. This occurs because the smart contract fails to validate that the resulting token balance would not exceed the maximum value that can be represented by the underlying integer data type. The vulnerability is particularly dangerous because it grants the contract owner unlimited control over user balances, effectively allowing them to create unlimited tokens or manipulate existing balances to arbitrary values.
From an operational security perspective, this vulnerability creates a severe threat model where the contract owner can essentially bypass the normal token economics and distribution mechanisms. The impact extends beyond simple financial loss as it undermines the fundamental trust in the token's integrity and the blockchain's immutability principles. An attacker with access to the owner account can manipulate token distributions, potentially creating artificial scarcity or flooding the market with tokens. This vulnerability also impacts the security posture of the entire token ecosystem, as it can be used to manipulate token prices, create artificial trading patterns, or even facilitate more sophisticated attacks such as reentrancy exploits or front-running scenarios.
The mitigation strategies for this vulnerability involve implementing proper integer overflow protection mechanisms in smart contract code. This includes utilizing SafeMath libraries or similar arithmetic libraries that perform overflow checks before executing arithmetic operations. Additionally, developers should implement comprehensive input validation and parameter checking within all functions that manipulate token balances or perform arithmetic operations. The vulnerability demonstrates the critical importance of adhering to secure coding practices in blockchain development and aligns with ATT&CK technique T1548.001 for privilege escalation through smart contract manipulation. Organizations should conduct thorough code reviews, implement automated security testing, and ensure proper access control measures are in place to prevent unauthorized access to contract owner privileges. The fix requires updating the mintToken function to include overflow protection and validation checks to prevent the arithmetic operations from exceeding the maximum integer limits, thereby preventing the malicious manipulation of user token balances.