On Sunday, NewsHour Weekend examines an increasingly prevalent form of computer hacking that's also draining victims' bank accounts: Ransomware. It's a type of software that hackers use to hold individuals' computers hostage, blocking access to all files, unless they agree to pay a ransom, usually with Bitcoins. And because anyone with an internet connection is vulnerable to attack, the problem highlights a growing threat that consumers face on both their personal computers and mobile devices. NewsHour's William Brangham reports from Massachusetts.