By Emily Flitter and Tanya Agrawal (Reuters) - A brazen gang of cyber criminals, who stole $45 million from bank ATMs in 27 countries, exposes an Achilles heel in the global financial industry: prepaid debit cards. Cyber security experts and industry analysts say the burgeoning use of prepaid debit cards for everything from gift certificates to disaster relief handouts is making it easier for hackers to withdraw large amounts of money before detection. Prepaid cards have fewer controls on them than on regular credit and debit cards issued by banks. ...