This is beautiful, but the real takeaway should be that even proprietary software you only have binaries for is still mutable. The computer runs the code you want it to run. We always need to maintain that and prevent scenarios where general purpose computers stop being the default.
We were always doing this kind of thing on these platforms. This is how we used to hack copy protection out of games.
Stepping through, line by line, editing the code and adding JMPs to get around the copy protection code after loading the magic numbers into the register...
Happy, happy times.
Then they started loading the protection code from disk doing tricky things. One I cracked recently was a pair of Commodore 1541 sectors that appeared to be the same logical sector (because the drive head is blind). It needed to hit both of them to compile the next portion of the loader. Naturally the segment up to that point was encrypted as well, but nothing survives a VICE breakpoint. https://oldvcr.blogspot.com/2023/08/cracking-designwares-gra...
Obviously this is nothing on things like V-MAX! and Rapidlok which even nowadays have variations that are tough to remaster.
That's how I first learned assembly. Armed with a monitor program that can disassemble and modify memory, I read and modified programs stepping through them. Mostly games, naturally. I never got an actual assembler/linker chain that would work and useful software was hard to come by.
Unfortunately the whole "open source" movement has diverted attention away from that and brainwashed countless would-be power-users and even developers into believing that they are powerless to do anything without the source code. It's convenient to have the source, but not necessary for freedom.
Cat's out of the bag there already. We all have general purpose computing devices in our pockets, locked down on purpose. Android used to allow you to gain admin rights but it's been getting more and more impossible to do so while still keeping most of your programs working. It's not only a cat-and-mouse game against "rooting detection" SDKs companies licence and plug into their apps out of a misguided duty of care, but it's especially bad with anything that uses Google's remote attestation lately.
Android is also about to lock down "sideloading", another "great" dysphemism for "installing software".
Moving the Overton window on this has been so successful, that even people in our industry happily accepted the much maligned dysphemisms of "jailbreaking" and "rooting" for what used to be called "local admin rights" and look upon such access as if it's only something pirates, criminals or malware spreaders would want to do.
I say this as someone who is running an Android phone with a kernel with some backported patches applied and compiled by myself. The fact that I can do it is great. The fact that the entire industry is trying to make it as frustrating as possible for me to do this under the guise of false premises such as "security" is disheartening.