Chinese hackers behind U.S. ransomware attacks - security firms

Hackers using tactics and tools previously associated with Chinese government-supported computer network intrusions have joined the booming cyber crime industry of ransomware, four security firms that investigated attacks on U.S. companies said.

Ransomware, which involves encrypting a target's computer files and then demanding payment to unlock them, has generally been considered the domain of run-of-the-mill cyber criminals.

But executives of the security firms have seen a level of sophistication in at least a half dozen cases over the last three months akin to those used in state-sponsored attacks, including techniques to gain entry and move around the networks, as well as the software used to manage intrusions.