Flickr/Kārlis Dambrāns An Israeli company named NSO Group is reportedly behind the hacking tool for iPhones that forced Apple to issue a critical software update on Thursday.

The tool was apparently discovered in a hacking attempt on a human rights activist in the United Arab Emirates, but details on the ultra-secretive company are hard to come by.

That's because NSO Group sells sophisticated hacking tools to governments, militaries, and intelligence agencies — and it tries to keep such a low profile it even changes its name on a regular basis.

Its profile is likely to be raised in the wake of in-depth research by Lookout Security and Citizen Lab's Bill Marczak and John Scott-Railton, who exposed a major iOS security flaw that allows an attacker to take full control of an iPhone using nothing more than a text message.

NSO Group cofounders Omri Lavie and Shalev Hulio did not respond to a request for comment.

Here's what we know so far.