Twenty Four: I Broke AWS Again

Again?

Yes, again. You may remember that last time, I broke AWS because I wiped my harddrive and therefore lost my SSH key. This time, I made a different error that literally broke my Debian instance.

The sin

Admittedly, I don’t really blame myself for this one. I was busy setting up a Docker compose file for a CTF challenge (Sub-Z3R0 CTF coming soon, Dec 2!). For reasons I prefer not to get into, I was trying to do something janky and I copied my sudo binary into the container and changed the permissions. Little did I know, if you copy a file into a Docker container and then modify its permissions in the container, the original file’s permissions are modified too. I am not 100% sure that this is correct and maybe I just made a dumb mistake, but next thing I knew, I could no longer use sudo in my instance because I had modified the permissions. Uh oh. I can’t fix the sudo permissions because, well, I need sudo for it. And to run docker containers, I need sudo too, because I hadn’t added myself to the docker group. I had no other option (please correct me if there was something else I could do). I tried everything I found online, but the nuclear option stared me in the face. Of course, I had to detach the volume, create a new instance and attach the volume to that one and mount it, fix the sudo permissions, and reattach the volume to the original instance to get back to normal.

Stupid mistakes

Interestingly enough, I made this grave mistake when I first mounted the volume to a new instance

cd /mnt/
cd /usr/bin/
chmod ... sudo

You may have caught my error. That is, I cd’ed to my OWN /usr/bin/ instead of the mnt/usr/bin. I then screwed up sudo on accident in my new instance that I created specifically to fix it! So, I had to create yet another instance and fix the problem there.

I am glad that I knew exactly how to fix the issue (with detaching the volume) immediately when I made the original sin. It feels good to know how to fix something immediately because you have made a mistake like it before. It does truly feel like I am learning.

This is being posted on Thanksgiving. If you’re reading this, I am thankful for you, and I hope you do not make the same mistake I did. Or, if you did, then perhaps you may benefit from my solution.