Firefox extention not blocked, spreads to host

[capturewiz]

Normally, an extension added to a sandboxed instance of Firefox stays in the sandbox. It's blocked from appearing in normal, unprotected instances of Firefox.

However, I recently installed a suspicious TV viewing extension in a sandboxed instance of Firefox and was surprised to discover the extension had spread to the host machine.

You can duplicate the problem by following these four steps...

1 Open a sandboxed instance of Firefox.

2 Install an extension.

3 Open an unprotected instance of Firefox.

4 The extension will magically appear in the unprotected instance of Firefox.

[Conadan]

Have you allowed direct access to your whole Firefox profile?

[bo.elam]

You can duplicate the problem by following these four steps...

I tried to reproduce what you are saying by installing DownloadHelper sandboxed. Then I opened an unsandboxed version of Firefox. The extension did not appear. You should create a new sandbox and run Firefox in it, then install an extension to see what you get.

Bo

[Dun]

Make sure Firefox sync is disabled for sandboxed firefox.
I would do it that way:
config what needed outside of sandbox, start sandboxed, disable internet connection, disable FF sync for sandboxed FF, then finally config sandboxed FF