escapeshellarg() dangerous on windows (always assumes bash escape rules)

[divinity76]

• Have you checked the guidelines in our Contributing document?

Description

Windows/cmd has quite different escaping rules from bash, and the current escapeshellarg() function always assumes it's running on bash, even if it's running on windows. this could allow hackers to execute programs on command-line-arguments created from user input. for example:

user_input="test.txt & dir &;";
cmd="notepad "+escapeshellarg(user_input);

• here the programmer have correctly used escapeshellarg() to create the cmd argument in a safe way, where the user decide what file to open with notepad, but nothing more. but because of the bug, even on MS Windows the command becomes:

notepad 'test.txt & dir &;'

which to microsoft's cmd.exe means roughly: open notepad with the argument test.txt and run the command dir simultaneously

.. escapeshellarg() needs to check if it's running on Windows or not, and then use OS-specific escape rules, at least that's what PHP's escapeshellarg() does.

[Oskar Larsson Högfeldt]

I think this function should just be removed. I mean, what's the correct behaviour on the Web, which has no shell?

[Oskar Larsson Högfeldt]

And what about other operating systems that aren't Windows or UNIX? Just throw an error?

[divinity76]

well the php behavior is to check if it's running on Windows, if yes use cmd escape-rules, otherwise use POSIX escape rules..

not sure if we should follow suite or delete the function. anyhow, you can apparently check if you're running on Windows or not by running

if((typeof window === "undefined" ? process.platform : window.navigator.platform).toString().indexOf("Win") === 0 ){
// running on Windows
} else {
// Not windows
}