Author: Miguel
Source: Solidity Audit Checklist
Info
- All functions are
internal
except where explictly required to bepublic
/external
. [?] - There are no arithmetic overflows/underflows in math operations.
- Using the OpenZeppelin safe math library [?].
- Ether or tokens cannot be accidentally sent to the address
0x0
. - Conditions are checked using
require
before operations and state changes. - State is being set before and performing actions.
- Protected from reentry attacks (A calling B calling A). [?]
- Properly implements the ERC20 interface [?].
- Only using modifier if necessary in more than one place.
- All types are being explicitly set (e.g. using
uint256
instead ofuint
). - All methods and loops are within the maximum allowed gas limt.
- There are no unnecessary initalizations in the constructor (remember, default values are set).
- There is complete test coverage; every smart contract method and every possible type of input is being tested.
- Performed fuzz testing by using random inputs.
- Tested all the possible different states that the contract can be in.
- Ether and token amounts are dealt in wei units.
- The crowdsale end block/timestamp comes after start block/timestamp.
- The crowdsale token exchange/conversion rate is properly set.
- The crowdsale soft/hard cap is set.
- The crowdsale min/max contribution allowed is set and tested.
- The crowdsale whitelisting functionality is tested.
- The crowdsale refund logic is tested.
- Crowdsale participants are given their proportional token amounts or are allowed to claim their contribution.
- The length of each stage of the crowdsale is properly configured (e.g. presale, public sale).
- Specified which functions are intented to be controlled by the owner only (e.g. pausing crowdsale, progressing crowdsale stage, enabling distribution of tokens, etc..).
- The crowdsale vesting logic is tested.
- The crowdsale has a fail-safe mode that when enabled by owner, restricts calls to function and enables refund functionality.
- The crowdsale has a fallback function in place if it makes reasonable sense.
- The fallback function does not accept call data or only accepts prefixed data to avoid function signature collisions.
- Imported libraries have been previously audited and don't contain dyanmic parts that can be swapped out in future versions which can be be used maliciously. [?]
- Token transfer statements are wrapped in a
require
. - Using
require
andassert
properly. Only useassert
for things that should never happen, typically used to validate state after making changes. - Using
keccak256
instead of the aliassha3
. - Protected from ERC20 short address attack. [?].
- Protected from recursive call attacks.
- Arbitrary string inputs have length limits.
- No secret data is exposed (all data on the blockchain is public).
- Avoided using array where possible and using mappings instead.
- Does not rely on block hashes for randomness (miners have influence on this).
- Does not use
tx.origin
anywhere. [?] - Array items are shifted down when an item is deleted to avoid leaving a gap.
- Use
revert
instead ofthrow
. - Functions exit immediately when conditions aren't meant.
- Using the latest stable version of Solidity.
- Prefer pattern where receipient withdrawals funds instead of contract sending funds, however not always applicable.
- Resolved warnings from compiler.