PrusaSlicer 2.6.1 Arbitrary Code Execution

`# Exploit Title: PrusaSlicer 2.6.1 - Arbitrary code execution on g-code export  
# Date: 16/01/2024  
# Exploit Author: Kamil Breński  
# Vendor Homepage: https://www.prusa3d.com  
# Software Link: https://github.com/prusa3d/PrusaSlicer  
# Version: PrusaSlicer up to and including version 2.6.1  
# Tested on: Windows and Linux  
# CVE: CVE-2023-47268  
  
==========================================================================================  
1.) 3mf Metadata extension  
==========================================================================================  
  
PrusaSlicer 3mf project (zip) archives contain the 'Metadata/Slic3r_PE.config' file which describe various project settings, this is an extension to the regular 3mf file. PrusaSlicer parses this additional file to read various project settings. One of the settings (post_process) is the post-processing script (https://help.prusa3d.com/article/post-processing-scripts_283913) this feature has great potential for abuse as it allows a malicious user to create an evil 3mf project that will execute arbitrary code when the targeted user exports g-code from the malicious project. A project file needs to be modified with a prost process script setting in order to execute arbitrary code, this is demonstrated on both a Windows and Linux host in the following way.  
  
==========================================================================================  
2.) PoC  
==========================================================================================  
  
For the linux PoC, this CLI command is enough to execute the payload contained in the project. './prusa-slicer -s code-exec-linux.3mf'. After slicing, a new file '/tmp/hax' will be created. This particular PoC contains this 'post_process' entry in the 'Slic3r_PE.config' file:  
  
```  
; post_process = "/usr/bin/id > /tmp/hax #\necho 'Here I am, executing arbitrary code on this host. Thanks for slicing (x_x)'>> /tmp/hax #"  
```  
  
Just slicing the 3mf using the `-s` flag is enough to start executing potentially malicious code.  
  
For the windows PoC with GUI, the malicious 3mf file needs to be opened as a project file (or the settings imported). After exporting, a pop-up executed by the payload will appear. The windows PoC contains this entry:  
  
```  
; post_process = "C:\\Windows\\System32\\cmd.exe /c msg %username% Here I am, executing arbitrary code on this host. Thanks for slicing (x_x) "  
```  
  
`