OSX/Dok is a Trojan horse that is capable to bypass Apple’s protections and hijack all traffic entering and leaving your Mac without your knowledge.
Unfortunately, the malware used to have a legitimate certificate, thus the macOS’s Gatekeeper would not prevent its execution. However, after Apple has revoked it and updated the XProtect, it has been considered as a malware signature system.
Yet, hackers still could gain access to users’ communication by redirecting traffic through a malicious proxy server.
The OSX/Dok malware was infecting the OS X users via an email phishing campaign. Thus, the best way to avoid having this malware onto the system is not responding to emails requiring you to enter a password or install any new applications.