This is a open-source C# example file that you can use for free! I made it especially for Ransomware test.
The five detections on VirusTotal are just false positives! VirusTotal: https://www.virustotal.com/gui/file/49bf518151f4af5ac8ae83310e20a10bee8e6ff5fae0cb69b08443a8271356d3/detection
To download the file, you need to click on the latest version at the lower right corner.