Whole article how they made it - https://googleprojectzero.blogspot.com
Explanation what they have made - Pegasus_(spyware).
The lesson from the whole article is that there are still programmers who can work without using https://stackoverflow.com!
As we say in my homeland - "the road to hell is paved with good intentions ..."
The result of their briliant work is simply awwful!
Please note another interesting idea, using the same concept - "Open Redstone project" and his description.