TeamViewer has been the victim of a cyber attack which was discovered during the autumn of 2016, but was never disclosed. This attack is thought to be of Chinese origins and utilized the Winnti backdoor. Experts and investigators failed to find any evidence of data being stolen during the security incident. No evidence was found that the hackers were able to compromise or steal source code even though they had access to it. Backdoor malware was also removed after a data center overhaul and all systems were “completely checked
Source: security