Command Injections

To inject an additional command to the intended one, we may use any of the following operators:

Injection Operator	Injection Character	URL-Encoded Character	Executed Command
Semicolon	;	%3b	Both
New Line		%0a	Both
Background	&	%26	Both (second output generally shown first)
Pipe	|	%7c	Both (only second output is shown)
AND	&&	%26%26	Both (only if first succeeds)
OR	||	%7c%7c	Second (only if first fails)
Sub-Shell	``	%60%60	Both (Linux-only)
Sub-Shell	$()	%24%28%29	Both (Linux-only)

In addition to the above, there are a few unix-only operators, that would work on Linux and macOS, but would not work on Windows, such as wrapping our injected command with double backticks (``) or with a sub-shell operator ($()).

In general, for basic command injection, all of these operators can be used for command injections regardless of the web application language, framework, or back-end server. So, if we are injecting in a PHP web application running on a Linux server, or a .Net web application running on a Windows back-end server, or a NodeJS web application running on a macOS back-end server, our injections should work regardless.

The only exception may be the semi-colon ;, which will not work if the command was being executed with Windows Command Line (CMD), but would still work if it was being executed with Windows PowerShell.