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38 lines
1.3 KiB
Markdown
38 lines
1.3 KiB
Markdown
## smart contract vulnerabilities
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### tl; dr
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* `tx.origin` needs to bere placed by `msg.sender`, otherwise any contract you call can act on your behalf.
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* inline assembly should be used only in rare cases.
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* unclear semantics: `now` is alias for `block.timestamp` not current time; use of low level `call`, `callcode`, `delegatecall` should be avoided whenever possible; use `transfer` whenever failure of ether transfer should rollnack the whole transaction.
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* beware of caller contracts: `selfdestruct` can block calling contracts unexpectedly.
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* invocation of local functions via `this`: never use `this` to call functions in the same contract, it only consumes more gas than normal call.
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* transferring Ether in a for/while/do-while loop should be avoid due to the block gas limit.
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* erc20 `decimals` should have `uint8` as return type.
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<br>
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---
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### in this dir
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* [reentrancy](reentrancy_attacks)
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* [randomness in ethereum](random_numbers.md)
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* [code injection via `delegatecall`](delegatecall)
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* [ddos attacks](ddos.md)
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<br>
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----
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### resources
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* [secureum-mind-map](https://github.com/x676f64/secureum-mind_map/blob/master/3.%20Solidity%20201.md)
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* [defi hacks & exploits](https://github.com/SunWeb3Sec/DeFiHackLabs/#list-of-defi-hacks--exploits)
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* [ethereum smart contract security best practices](https://consensys.github.io/smart-contract-best-practices/)
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