The use of the legitimate regsvr32.exe application to run a .sct file is an AppLocker bypass technique originally discovered by Casey Smith (@subtee), which eventually resulted in a Metasploit module. The WINDOWSTEMP.ps1 script is a dropper that decodes an embedded executable using base64 and decompresses it with the System.IO.Compression.GzipStream object. The WindowsTemplate.exe executable is a new variant of RogueRobin written in C