使用Burp Suite
在Target下的Site mape中找到
http://123.206.87.240:9009
单击，在Burp Suite右下侧Response下的Raw中会看到
HTTP/1.1 200 OK
Server: nginx
Date: Sun, 17 Mar 2019 12:51:05 GMT
Content-Type: text/html
Connection: keep-alive
Keep-Alive: timeout=60
flag{Bugku_k8_23s_istra}:
Content-Length: 139
<html>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<pre><br><br><br><br>什么也没有。<br><br>
</html>
即可找到flag{Bugku_k8_23s_istra}