I am trying to check if I installed a malicious chrome extension which can steal credit card data. That may be some extension that has an access to all data on all sites. chrome:://extensions does not seem to have this data. How can I check which data is available to google chrome extension?
The premise that extension requests permissions and hence can steal your data is false. Having said that, if you want to check the permissions, then while installing you get a list of things the Extension can access.
To review this post installation, Head over to the Extensions page,
Click on the "Visit Website" & then on the details tab.
You'll see the permissions listing on the lower right corner.
Another way is to head over to %localappdata%\Google\Chrome\User Data\Default\Extensions\id where id is the id below the extension(to show the id, Developer mode tickbox must be checked. From this folder, you can examine the manifest file to see what it requests. Of course, you can go one step further & just examine the entire extension source code itself.