Bloomberg: Carbanak’s suspected ringleader is under arrest, but $1.2 billion remains missing, and his malware attacks live on.

“Since late 2013, this band of cybercriminals has penetrated the digital inner sanctums of more than 100 banks in 40 nations, including Germany, Russia, Ukraine, and the U.S., and stolen about $1.2 billion, according to Europol, the European Union’s law enforcement agency. The string of thefts, collectively dubbed Carbanak—a mashup of a hacking program and the word “bank”—is believed to be the biggest digital bank heist ever. In a series of exclusive interviews with Bloomberg Businessweek, law enforcement officials and computer-crime experts provided revelations about their three-year pursuit of the gang and the mechanics of a caper that’s become the stuff of legend in the digital underworld. Besides forcing ATMs to cough up money, the thieves inflated account balances and shuttled millions of dollars around the globe. Deploying the same espionage methods used by intelligence agencies, they appropriated the identities of network administrators and executives and plumbed files for sensitive information about security and account management practices. The gang operated through remotely accessed computers and hid their tracks in a sea of internet addresses. “Carbanak is the first time we saw such novel methods used to penetrate big financial institutions and their networks,” says James Chappell, co-founder and chief innovation officer of Digital Shadows Ltd., a London intelligence firm that works with the Bank of England and other lending institutions. “It’s the breadth of the attacks, that’s what’s truly different about this one.”…