A simple Rat I did in C # with the following options: [+] Open and close reading [+] List files in a directory [+] Delete files and directories [+] See the contents of a file [+] Make the keyboard just type[+] Open Word and to vary things only the keyboard writes [+] Send messages [+] Make the computer talk (in English) [+] List processes [+] Kill a process [+] Run command and see the outcome [+] Back crazy mouse for a while [+] Hide and display the taskbar [+] Hide and show desktop icons [+] Keylogger included An image:

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If you want to lose what they can do  here