What you can do with this?

• Static analysis: you can do a basic manual code review for decompiled sources to discover hidden communication channels, search for hard-coded passwords, or SQL injection vulnerabilities.
• Import decompiled projects to an IDE to reconstruct and modify the original source code
• Call hidden native exported functions with rundll32

Here is a rough description of what it does, and what tools it is using:

• For exe, dll files:
  
  • Detect and de-obfuscate for .NET libraries with de4dot 
  • Decompile .NET libraries with JustDecompile 
  • Zip decompiled source code to netsources.zip 
  • Run strings against native libraries
  • Export call-able functions with dllexp. You can then try to run those functions with command Rundll32 , 
  • Export dependencies with depends 
  • Extract native resources with resourcesextract 

• For jar files: 
  
• Extract and combine java classes into a single zip file
• Decompile java sources with procyon 
• Zip decompiled source code to javasources.zip