Just a short note for today. As a hacker of NAS boxes I often find it’s tricky to keep the original firmware and enhance it much. Many NAS’s have a thriving community of people working out how to get in, modify or replace firmware. I’d always suggest starting at NAS_Central first. Even if your specific NAS isn’t listed many of the articles are for similar devices and can offer clues on where to go.
Many, many people compile binaries for many purposes, and if you’re not into compiling or just want to add a simple command (SU, a decent IFCONFIG or something) just ripping a binary can be quick and effective as long as you understand dependencies. Often new binaries need newer flavours of linux on the box which gets tricky again. Understanding how different chips work can help.
One useful site I found recently Exploiting ARM binaries has some really good (and simple) background on some of the older ARM chips, their foibles and how to disassemble/run on QEMU
**Update 22/5/19 – NAS Central appears to be off air again since early 2019. You can look at much of the content with the Wayback machine: https://web.archive.org/web/20190314085609/nas-central.org/wiki/main_page **