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Akutar NFT 损失 3400 万美元

Code Auditing
April 23, 2022
2 min read

我们在 @AkuDreams 合约中发现了两个严重逻辑漏洞: https://etherscan.io/address/0xf42c318dbfbaab0eee040279c6a2588fa01a961d

第一个漏洞可能导致拒绝服务 (DoS) 攻击,第二个漏洞将导致项目资金(超过 3400 万美元)被永远锁定。

漏洞 I

第一个漏洞存在于 processRefunds 函数中。该函数包含一个循环,用于退还每个竞拍用户的资金。然而,竞拍者可能是一个恶意合约,会回滚交易。这可能导致 processRefunds 函数调用回滚,所有用户的退款都将失败。幸运的是,此漏洞尚未被利用。

我们建议合约可以采取以下措施进行退款:

  • 确保只有 EOA(外部所有者账户)可以竞拍
  • 使用 ERC20 代币,例如 WETH,而不是 ETH
  • 提供一个允许用户自行领取退款的函数

漏洞 II

第二个漏洞是一个软件 bug。在 claimProjectFunds 函数中,项目所有者可以提取合约中的 Ether。然而,require(refundProgress >= totalBids, "Refunds not yet processed"); 这个 require 语句存在 bug,它应该将 refundProgress_bidIndex 进行比较,而不是 totalBids。由于这个漏洞,条件永远无法满足,合约中的 Ether(11,539.5 Ether)可能会永远被锁定。

总结

我们再次感到惊讶(继昨天的 NBA NFT 事件之后),一个备受瞩目的项目怎么会忽视基本的软件安全实践。至少,项目应该编写足够的测试用例。不幸的是,我们怀疑项目方可能因为太忙而未能编写测试用例,最终损失了 3400 美元。

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