Coldroot, a remote access trojan (RAT), is still undetectable by most antivirus engines, despite being uploaded and freely available
on GitHub for almost two years.
The RAT appears to have been created as a joke, "to Play with Mac users," and "give Mac it's rights in this [the RAT] field," but has since expanded to work all three major desktop operating systems — Linux, macOS, and Windows— according to a screenshot of its builder extracted from a promotional
YouTube video.
But despite being open-sourced in 2016, the RAT remained in anonymity, never being at the center of major cybercrime operations. Unfortunately, things appear to have changed in the meantime, and the RAT has now entered active distribution.