0x01. Enter the environment and view the content

The title interface is shown in the figure:

Title hint:Xiaoning wrote a ping function, but not waf. Teacher X told her that it was very dangerous. Do you know why?
emmm, waf may be the key to solving the problem

0x02. Problem Analysis

0x02_1. What is waf

Web application protection system (also known as: website application-level intrusion prevention system. English: Web Application Firewall, referred to as: WAF).Using an internationally recognized saying: Web application firewall is a product that provides protection for Web applications by implementing a series of HTTP/HTTPS security policies.If waf is not turned on, there will be problems such as web pages being tampered with.

0x02_2. Related Commands

You need to be familiar with linux commands here:

Under windows or linux:
command1 && command2 execute command1 first, if true, then execute command2
command1 || command2 execute command1 first, if false, then execute command2
command1 & command2 firstExecute command1 after executing command2
command1 | command2 only execute command2
Command execution vulnerability (| || & && is called pipe character)

0x02_3. Command Test

In any case, the ping command must be able to ping the host, so it must be able to complete ping 127.0.0.1, and the command must be executed successfully.

Secondly, using keywords for full-text search, we can construct a retrieval payload: 127.0.0.1 | find / -name "flag*", as shown in the figure, the word "flag" is returned.

In this case, don't be polite, construct the payload againView flag.txt, the content is: 127.0.0.1 | cat /home/flag.txt, as shown in the figure:

The final answer is: cyberpeace{140607f89048a8ce053e9fc36fdb34c0}