threat-modeling.md

Threat Model Analysis for ethereum/solidity

Threat: Reentrancy Vulnerability

• Description: An attacker exploits external calls within a Solidity function. By crafting a malicious contract, the attacker can force a recursive call back into the original vulnerable function before the initial call completes its state updates. This allows for repeated execution of actions, like withdrawing funds multiple times when only intended once.
• Impact: Loss of contract funds, unauthorized state changes, potential contract compromise.
• Solidity Component Affected: Function calls, external calls (call, send, transfer), state variables.
• Risk Severity: Critical
• Mitigation Strategies:
  • Implement the Checks-Effects-Interactions pattern in Solidity code.
  • Utilize reentrancy guard modifiers in Solidity to prevent recursive calls.
  • Favor pull payment patterns in Solidity where users initiate withdrawals.

Threat: Integer Overflow/Underflow

• Description: In Solidity versions before 0.8.0, arithmetic operations on integer types (uint, int) could wrap around upon exceeding maximum or falling below minimum values. Attackers could exploit this in Solidity code to manipulate calculations, leading to incorrect logic, for example, in token balances or access control checks.
• Impact: Incorrect contract logic execution, financial losses due to manipulated values, bypass of intended security checks.
• Solidity Component Affected: Arithmetic operators (+, -, *, /), integer data types (uint, int).
• Risk Severity: High (for Solidity versions < 0.8.0)
• Mitigation Strategies:
  • Upgrade to Solidity version 0.8.0 or later, which includes built-in overflow/underflow checks.
  • For older Solidity versions, use safe math libraries like OpenZeppelin's SafeMath in Solidity code.

Threat: Access Control Bypass

• Description: Flaws in Solidity access control implementation allow unauthorized users to execute privileged functions. This can occur due to missing access control modifiers, incorrect conditional logic in access control checks within Solidity functions, or vulnerabilities in custom access control mechanisms written in Solidity.
• Impact: Unauthorized actions performed on the contract, modification of critical state variables, potential loss of funds or contract takeover.
• Solidity Component Affected: Modifiers (onlyOwner, onlyRole, custom modifiers), function visibility (private, internal, public, external), conditional statements in Solidity.
• Risk Severity: Critical
• Mitigation Strategies:
  • Implement robust access control using Solidity modifiers and role-based access control patterns.
  • Clearly define and enforce access control logic within Solidity functions.
  • Thoroughly review and test access control mechanisms implemented in Solidity code.

Threat: Delegatecall Vulnerability

• Description: The delegatecall function in Solidity executes code from an external contract within the storage context of the calling contract. If a contract uses delegatecall to interact with an untrusted or vulnerable external contract, malicious code from the external contract can directly manipulate the storage of the calling contract, leading to severe vulnerabilities.
• Impact: Complete compromise of the calling contract, arbitrary state changes, loss of funds, potential contract destruction.
• Solidity Component Affected: delegatecall function, contract storage, external contract interactions via delegatecall.
• Risk Severity: Critical
• Mitigation Strategies:
  • Exercise extreme caution when using delegatecall in Solidity.
  • Only use delegatecall with thoroughly audited and trusted external contracts.
  • Carefully manage storage layout and potential conflicts when using delegatecall.
  • Consider using call instead of delegatecall in Solidity if storage context sharing is not required.

Threat: Logic Errors and Bugs in Smart Contract Code

• Description: Unintentional errors or flaws in the Solidity code logic can lead to unexpected behavior and vulnerabilities. Attackers can exploit these logic errors to manipulate contract state, bypass intended functionality, or cause financial losses. These bugs can be subtle and arise from complex business logic, incorrect assumptions, or overlooked edge cases in Solidity code.
• Impact: Unpredictable contract behavior, security vulnerabilities exploitable by attackers, financial losses, denial of service, data corruption.
• Solidity Component Affected: All aspects of Solidity code: functions, state variables, control flow, data structures, business logic implementation.
• Risk Severity: High to Critical (depending on the severity of the logic error)
• Mitigation Strategies:
  • Adhere to secure coding practices and best practices for Solidity development.
  • Write comprehensive unit and integration tests in Solidity to cover various scenarios and edge cases.
  • Conduct thorough code reviews by experienced Solidity developers.
  • Utilize static analysis tools specifically designed for Solidity to detect potential vulnerabilities.
  • Consider formal verification techniques to mathematically prove the correctness of critical Solidity code sections.