如何错误地验证签名——AssociationNFT案例

Code Auditing

April 21, 2022

2 min read

The Association NFT 是一个由 NBA 推出的 NFT。然而，我们发现该 NFT 销售合约存在严重的漏洞，允许攻击者在不支付任何代币的情况下铸造大量 NFT。

该漏洞的根本原因是签名验证的错误使用。基本上，合约未能确保签名只能由用户（且仅由用户）使用一次。在这种情况下，攻击者可以重复使用特权用户的签名，并将代币铸造给自己。

我们可以看到，在 verify 函数中，签名中不包含发送者的地址。此外，没有机制来包含一个 nonce 以确保签名只能使用一次。这些安全要求是软件安全课程中的基本知识。

我们很惊讶如此普遍的 NFT 项目中会出现这样的漏洞。整个社区都需要更加关注合约的安全性。

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