DVWA Clearance Log 2 - Command Injection

Command injection

In simple terms, the most basic thing about command injection is to grasp the meaning of the following command connectors, and then select them according to the actual situation.

You need to mention a small point of attention. If the returned 64-bit package, then the probability of the operating system of the unix system is high, and if it is a 32-bit package, the probability of the windows system is high.Of course, the whole return body is not the same, you can try the following commands according to this.

semicolon ;

commands are executed in sequence, if the previous command fails to execute, the latter command will be executed directly, so this is a more commonly used method, and there is no need to wait for the previous ping time.

For example

ping 127.0.0.1;tail /etc/passwd

return result:

|| logical OR

This is easy to understand. In this case, the command on the left is returned directly after the execution is successful, because the result of true || false is true, so as long as the left side succeeds, the right side is "short-circuited".

&& logical AND

As opposed to || above, if the execution of the left fails, the execution of the right does not.Because false&&true results in false, the right side is still "shorted" in this case.

& Background execution

On the linux platform, if the command is followed by a &, it means that the command is executed in the background.

So

ping 127.0.0.1&tail /etc/passwd

means that ping is executed in the background and only returns the backCommand:

|The pipe character

The output of the previous command is used as the input of the following command, and the pipe character is often used for filtering, such as

x|tail /etc/passwd|grep "www-data"