The Lending & Borrowing Deep Dive
@EthSecurity1
https://dacian.me/lending-borrowing-defi-attacks

How Avoid oracle manipulation

This thread will be focused on the Chainlink oracles and how to deal with them, since they are one of the most popular choices.

https://twitter.com/saxenism/status/1656632735291588609?s=21
@EthSecurity1

Watch out for arbitrary NFT approvals inside of loops! 👇

If you attempt to call the "setApprovalForAll" function on an AxieInfinity NFT for an address that already has approval, it will revert.
@EthSecurity1

Great reveals on NFT

https://medium.com/web-design-web-developer-magazine/the-offset-approach-to-fair-nft-reveals-and-other-metadata-reveal-strategies-considerations-2e2c69e5c274
@EthSecurity1

The CoreCollection.withdraw function uses payableToken.transferFrom(address(this), msg.sender, amount) to transfer tokens from the CoreCollection contract to the msg.sender ( who is the owner of the contract). The usage of transferFrom can result in serious issues. In fact, many ERC20 always require that in transferFrom allowance[from][msg.sender] >= amount, so in this case the call to the withdraw function will revert as the allowance[CoreCollection][CoreCollection] == 0 and therefore the funds cannot ben withdrawn and will be locked forever in the contract.

Recommendation : replace transferFrom with transfer @EthSecurity1

tldr of tornado governance hack
1. hacker makes a proposal that executes code from a contract
2. users vote for the proposal since contract code looks good, proposal passes
3. hacker self-destructs contract and deploys malicious one in same address
4. 2nd contract is executed

so hacker got voters to vote a proposal, and, after the proposal passed, they changed the code for it and executed their malicious proposal, giving themselves full control of the DAO and draining the tokens held there.

another resource:

https://twitter.com/samczsun/status/1660012956632104960?s=21

@EthSecurity1

Storage collision because of lack of EIP1967 could cause conflicts and override sensible variables
Proof of Concept

contract CoreProxy is Ownable {
address private immutable _implement;

When you implement proxies, logic and implementation share the same storage layout. In order to avoid storage conflicts EIP1967 was proposed.(https://eips.ethereum.org/EIPS/eip-1967) The idea is to set proxy variables at fixed positions (like impl and admin ).

For example, according to the standard, the slot for for logic address should be

0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc (obtained as bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1) ).

In this case, for example, as you inherits from Ownable the variable _owner is at the first slot and can be overwritten in the implementation. There is a table at OZ site:https://docs.openzeppelin.com/upgrades-plugins/1.x/proxies @EthSecurity1

Anyone holding funds in Tornado Cash Nova must withdraw the funds ! The attacker can simply upgrade the contract (takes 7 days tho to execute) on Gnosis Chain (is managed by governance) and drain the ETH funds. For how to do it, see here

https://t.co/LXoG9cEMpn
@EthSecurity1

Getting flash loan without using the flash loan function. https://code4rena.com/reports/2023-04-caviar/#m-01-the-buy-functions-mechanism-enables-users-to-acquire-flash-loans-at-a-cheaper-fee-rate @EthSecurity1

Tornado Cash Hack - How to deploy different contracts at the same address

Notes
https://github.com/stakewithus/notes

References
https://twitter.com/storming0x/status/1660076433903869953

https://twitter.com/samczsun/status/1660012956632104960

https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
@EthSecurity1

lack of expiration timestamp check and slippage control. impact:
The transaction can be pending in mempool for a long and the trading activity is very time senstive. Without deadline check, the trade transaction can be executed in a long time after the user submit the transaction, at that time, the trade can be done in a sub-optimal price, which harms user's position.

The deadline check ensure that the transaction can be executed on time and the expired transaction revert. the second point is the slippage control:

require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
and
require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');

the slippage control the user can receive the least optimal amount of the token they want to trade.

In the current implementation, neither the deadline check nor the slippage control is in place when user deposit / withdraw / trade. @EthSecurity1

Chain abstraction is cool and save a lot of gas https://fxtwitter.com/ConnextNetwork/status/1661439482950811650 @EthSecurity1

This research introduces a novel pairs trading strategy based on copulas for cointegrated
pairs of cryptocurrencies: https://arxiv.org/pdf/2305.06961.pdf @EthSecurity1

Deploy Different Contracts at Same Address | Hack Solidity 0.8 youtu.be/zYaHtUJN-MI @EthSecurity1

The forgotten IPFS vulnerabilities https://consensys.net/diligence/blog/2022/09/the-forgotten-ipfs-vulnerabilities/
Fuzzing Tutorial: How to get started testing your smart https://consensys.net/diligence/blog/2023/04/fuzzing-tutorial-how-to-get-started-testing-your-smart-contracts/
Benchmarking Smart-Contract Fuzzers https://consensys.net/diligence/blog/2023/04/benchmarking-smart-contract-fuzzers/ @EthSecurity1

Auditing resources part 1:

Search for Audit reports
Audit Reports DeFi Yield
Past Audit Reports Solodit
Solutions to Blockchain Security CTF
Audit Findings Audit Hero
Security resources by Immunifi
Quill Audits Roadmap
Quill Auditing Mindmap
Quill Attack Vectors
web3 security
Metamask Signature Types
officercia.eth
SWC Registry
Security Guide by Crytic
DeFiHackLabs by Sunsec
DeFiVulnLabs
Smart Contract Best Practices by Consensys
Past Secureum Races
Certora Reports
Chain Security Audit Reports
Learn Advanced EVM/
Macro DAO Audit Reports
@EthSecurity1

New paper “Automated Market Making and Arbitrage Profits in the Presence of Fees” by jason_of_cs ciamac Tim_Roughgarden
@EthSecurity1
https://moallemi.com/ciamac/papers/lvr-fee-model-2023.pdf

Auditing resources part 2:
Security Compedium
Audit Reports - CD Security
YAcademy - DeFi Bugs
List of Reentrancy Attacks
Oracle Manipulation
Secure Contracts - Trail Of Bits
Immunify Bug Bounty Writeups
Audit Reports by Web3Sec News
Coinspect EVM Attacks
Solidity Notes by Chinmaya
Auditing Process by GA
Web3 Bugs
Secureum Mindmap @EthSecurity1