I am one of a few people managing a gaming server. The Server is currently running Ubuntu 14.04, which was installed just 3 weeks ago.
Everything was running fine until a few days ago, we've had a few issues. I suspect someone hacked into our SSH server and managed to seriously mess something up.
When I try to execute the command
sudo I get the following error:
sudo: unable to stat /etc/sudoers: No such file or directory
So first thought is the file got deleted and just needs to be recreated, however
ls /etc/ shows that the sudoers file already exists. Furthermore, when edited with nano (my preferred editor) It becomes apparent that the file is completely in tact and formatted correctly.
ls -l also shows that the sudoers file has the permissions
-r--r---- for user root and group root, which from research should be completely sufficient for sudo to be able to read the file, to make sure temporarily I gave the file
-rwxrwx--- for root root (were using tmux for session control and we already had a session up as root), still failed.
So the file exists, the content inside of it is correct, it has the proper permissions. What else could it be. I looked a bit at people who have had similar problems here on askubuntu.com, one solution I found that sounded hopeful, was to back up the sudoers file, then use:
apt-get purge sudo
apt-get install sudo
And then replace the new sudo file with the old one. This did not work unfortunately. To rule out farther that the sudoers file didn't have errors, I tried the solution again, and tried executing just
sudo with the newly created sudoers file, and got the same error.
-------- EDIT --------
For anyone interested in what the supposed non-existant sudoers file contains, here is a filtered version (usernames filtered) by request: http://paste.ubuntu.com/7781967/