An international hacking ring that's been active since at least the end of 2013 has stolen up to $1 billion from banks around the world, according to a cybersecurity firm report released Monday. The group has breached more than 100 banks in 30 countries through methods including programming ATMs to release money at certain times and transferring money to fake accounts, according to Russian security company Kaspersky Lab. The hackers become familiar with banks' systems through phishing, taking screen shots as well as filming employees using work computers, the report said. The theft targets banks instead of customers, which means the hackers are focused on stealing money rather than information, according to Kaspersky principal security researcher Vicente Diaz. Financial institutions in the U.S., Russia, Germany, China and Ukraine have been targeted, but the hackers may be casting a bigger net to include banks in Africa and Europe.