Here's an article updated in 2017 that lists several tools for helping with this. I was able to extract the VBA code out of a vbaProject.bin using the OfficeMalScanner tool. Edit: some months after successfully using this tool, Windows is detecting malware in it. The link was www dot reconstructer dot org / code / OfficeMalScanner.zip. Use at your own risk - it worked for me to extract a bunch of needed VBA code from the project after the source was lost.
