Hackers have exploited security weaknesses in SS7 protocol to break into a GMail account, take control of a bitcoin wallet and steal funds. The security issue in the Signaling System 7 could be exploited by criminals, terrorists and intelligence agencies to spy on communications. The attack method devised by the experts from Positive Technologies works against any service that relies on SMS to verify the user accounts, including Gmail and Twitter. The technique allows bypassing any security measure implemented by the giant of the social networks.”]
Source: http://securityaffairs.co/wordpress/63172/hacking/ss7-attacks.html