Upload File to File Server

The short answer is Yes, but not Out of the box. 

Longer answer. The only Out of the Box attachment options would be to use SharePoint or a SmartBox SmartObject with a File property. Two of the easiest options I can think of to get files on the file system are:

1. 
   
2. Create a custom Service Object that interacts with files directly on the file system. This shouldn't take all that much effort and allows you full flexibility in your implementation. There is also some VS templates so you do not have to start from scratch:
   http://www.k2underground.com/groups/visual_studio_project_templates_for_k2_blackpearl_extensions/default.aspx 
   
3. Write a web service, WCF Service or assembly that handles the operations and then consume these using the Dynamic WCF/Web Service/Assembly Service Broker.