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) "```