Strange message in terminal when visiting a website

I have my terminal open most of the time. Today while I was searching for a software, search results took me to http://download.cnet.com. I didn't like the software, closed the page and carried on.

When I brought may terminal back up (it was open the whole time on the background) I had a strange message on the prompt saying

No permission to use the keyboard API for http://download.cnet.com

What is this and how the heck it has gained handle to may terminal and should I be worried?

P.S.

I visited another url from that domain and the same happened.

I'm running firefox on OS X 10.6.8

I launched firefox via terminal.

You are getting that message because you launched Firefox from the command line.

I assume that you used & to put Firefox into the background but that doesn't redirect the output so any error will get written to your terminal session. To stop that appearing you need to add 2> /dev/null before the &.

See this answer for more :

https://stackoverflow.com/questions/18012930/how-to-redirect-all-output-to-dev-null

As for what the error means I assume that website has run some Javascript that hit Firefox's security system and bounced.

This error message is coming from a web server (download.cnet.com) attempting to take control of your keyboard. This is legitimate in cases where an application want to block your possibility to do a paste of a password or an E-mail address. There the purpose would be to force you to type it again.

Of course there are also many less legitimate cases where a web server would attempt to take control of your keyboard.

On the other hand, this web server didn't take control of any of your terminal (or windows). This warning message is due to the fact you fired Firefox through open within a Terminal. Then this command keep its standard error channel of communication attached to the originating Terminal window. This isn't a problem. On the other hand it is a very usefull way to debug an application without having to go dig for its error or warning messages within /var/log/system.log. Some application choose simply not to record warning messages when they are not attached to a window.

When you fire willingly an application from a Terminal window (either with open or ./my_command_to_debug &, it isn't mandatory nor usefull to hide these error messages.

They are showing and teaching you a lot.