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Jonas's Checklist

Summary

Author: Jonas

Source: Jonas's Checklist

Checklist

  1. Data

    a. Calculations

    • Integer Overflow-Underflow
    • Integer Division
    • Integer Sign
    • Integer Truncation
    • Wrong Operator
    • Conversion Problem
    • Decimals interoperability

    b. Hidden

    • Hidden built-in symbols
    • Hidden state variables
    • Incorrect Inheritance Order

    c. Initialization

    • Uninitialised Local/State variables
    • Uninitialised Storage variables

  2. Description

    a. Output

    • Right-to-Left-Override Control Character
    • Typo check
    • Check for events in admin changes
    • NatSpec incomplete

  3. Environment

    a. Supporting Software

    • Delete Dynamic Array Elements
    • Using continue-statements in do-while-statements

  4. Interaction

    a. Contract call

    • Reentrancy vulnerability
    • Reentrancy Read-only
    • Unhandled Exception
    • Unchecked return values
    • External calls without gas stipends
    • Calls to phantom functions (fallback)

    b. Ether flow

    • Forced to receive ether
    • Locked Ether
    • Pre-sent Ether

    c. ERC

    • Check for special ERC20 cases

  5. Interface

    a. Parameter

    • Call/Delegatecall data/address is controlled externally
    • Hash collision with multiple variable lenght arguments
    • Short address attack
    • Signature with wrong parameter

    b. Token Interface

    • Non-standard token interface

  6. Logic

    a.Assemble code

    • Returning results using assembly code in the constructor
    • Specify function variable as any type

    b. Denial of service

    • DOS by complex fallback function
    • DOS by gaslimit
    • DOS by non-existent address or malicious contract

    c. Fairness

    • Transaction order dependence
    • Frontrunning

    f. Timestamp dependence

    • Block.timestamp Manipulation
    • Long time to execute might be a problem

  7. Performance

    a. Gas

    • Byte[]
    • Invariants in loop
    • Invariant state variable are not declared constant
    • Unused public function within the contract should be declared as external

  8. Security

    a. Authority control

    • Replay Attack
    • Signature Maleability - OZ version < 4.7.3
    • Suicide Contracts
    • Use tx.origin for authentication
    • Wasteful Contracts
    • Wrong Constructor Name

    b. Privacy

    • Public data

  9. Standard

    a. Maintainability

    • Implicity Visibility Level
    • Nonstandard Naming
    • Too many digits
    • Unlimited Compiler Version
    • Use deprecated built-in symbols

    b. Programming Specification

    • View/contstant function changes contract state
    • Improper use of require, assert and revert
    • Check for EIPs implementation

  10. Bridges

    a. Precompiles

    • Check precompiles for Missing Call Checks (can be called with delegate calls)

  11. Attacks

    • Price Oracle Manipulation
    • Flash Loan Attacks
    • Cross-Chain Bridge Manipulation
    • Insolvency
    • Incorrect Slippage - When slippage % is fixed
    • Initial Supply Mint Issue
    • Malicious Honeypot (Compromised ERC20/ERC777/etc)
    • Sandwich Attacks

Complex Exploits:

  • Multiple contract reentrancy
  • Flash-loan to lend, borrow, burn and then liquidate itself

Common Lending/Borrowing Vulns

  • Liquidation Before Default
  • Borrower Can't Be Liquidated
  • Debt Closed Without Repayment
  • Repayments Paused While Liquidations Enabled
  • Collateral Pause Stops Existing Repayment & Liquidation
  • Liquidator Takes Collateral With Insufficient Repayment
  • Infinite Loan Rollover
  • Repayment Sent to Zero Address
  • Borrower Permanently Unable To Repay Loan
  • Borrower Repayment Only Partially Credited
  • Check if it's possible to lend and borrow same token - flash-loan + inflating price attack