[SOLVED] can't edit permissions of directory after changing them using "sudo chmod 444 etc"

Issue

I'm using Ubuntu 12.04.1 LTS (GNU/Linux 3.2.0-31-virtual x86_64) and changed the permissions of the "etc" directory to 444 (sudo chmod 444 etc). I now cant change the permissions to anything else and am receiving the following message:

$ sudo chmod 777 etc
sudo: unable to open /etc/sudoers: Permission denied
sudo: no valid sudoers sources found, quitting

I've tried to change to root user and change the permissions but I am prompted for a password which I was never asked to set, and am presented with this message:

$ su
Password:
su: Authentication failure

Solution

You should boot into "Ubuntu recovery mode" and change permissions back to /etc to 755:

https://askubuntu.com/questions/115358/changed-etc-permission-in-oneiric-ubuntu11-10-by-using-sudo-chmod-665-etc

Answered By - dAm2K

Answer Checked By - Candace Johnson (WPSolving Volunteer)