Is macOS online?

I revisited another previous project, msnciasm. I hadn’t used it in a while and wanted to again, but it threw up a EXC_BAD_ACCESS error.

The eventual fix was trivial (literally one character):

- mov r14d, [eax]
+ mov r14d, [rax]

However, I had not touch this particular project or assembly in so long it was daunting to know where to start. Basically like debugging someone else’s code in a language you don’t read. Fortunately, I had done a lot of reverse engineering binaries for Capture the Flag events, that was helpful to get me stepping through the code to troubleshoot and eventually worked out the fix.

Now I had a new problem, OSX is not a thing anymore, this is macOS. Just enough had changed that the binary wouldn’t build. Getting a working compile probably took longer than the actual fix. But got there in the end.

Updated msnciasm project on GitHub.