This is "well known" research that resurfaces every other year. Let me tell you a story how I have heard about this in 2012 and putting it into perspective.

Research "Scriptless Attacks –
Stealing the Pie Without Touching the Sill" (2012):
+ Paper: https://www.nds.rub.de/media/emma/ver...
+ Slides: https://www.slideshare.net/x00mario/s...
+ Talk recording: https://channel9.msdn.com/Events/Blue...

CSS Keylogger: https://github.com/maxchehab/CSS-Keyl...
Stealing Data With CSS - Attack and Defense: https://www.mike-gualtieri.com/posts/...

Twitter:
+ https://twitter.com/0x6D6172696F
+ https://twitter.com/sirdarckcat
+ https://twitter.com/garethheyes
+ https://twitter.com/thornmaker
+ https://twitter.com/mlgualtieri

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