Dear MetaMask Users,
There have been several instances of high-profile legitimate websites such as BTC Manager and Games Workshop that have had their websites temporarily compromised. This involves showing a fake MetaMask window on the page asking for user's seed phrases. MetaMask will never open itself in this way and users are encouraged to report these instances immediately to either our phishing blacklist or our support email at support@metamask.io

Here you can verify the sites they add as bad ones:
https://github.com/MetaMask/eth-phishing-detect/issues

How is the hack done? Some normally legit sites show you a popup in spot close to where MetaMask opens and you enter seed there by mistake.

Follow, Resteem and VOTE UP @kingscrown creator of http://fuk.io blog for 0day cryptocurrency news and tips!