ARTGALGANO, думаешь, ТС активировал <imunate> через chattr?
Интересная идея.
Сделал у себя
sudo chattr +i /etc/sudoers
и конечно же получил запрет на перемещение.
Попробую произвести ещё пару операций.
### UPD ###
Походу, ты прав:
root@tozen:/home/tozen# dpkg --purge --force-depends sudo
dpkg: sudo: dependency problems, but removing anyway as you requested:
ubuntu-minimal depends on sudo.
gksu depends on sudo.
(Reading database ... 225094 files and directories currently installed.)
Removing sudo (1.8.16-0ubuntu1.2) ...
Purging configuration files for sudo (1.8.16-0ubuntu1.2) ...
dpkg: error processing package sudo (--purge):
cannot remove old config file '/etc/sudoers' (= '/etc/sudoers'): Operation not permitted
Processing triggers for man-db (2.7.5-1) ...
Errors were encountered while processing:
sudo
root@tozen:/home/tozen# apt install sudo
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed
sudo
0 to upgrade, 1 to newly install, 0 to remove and 0 not to upgrade.
Need to get 389 kB of archives.
After this operation, 1,618 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 sudo amd64 1.8.16-0ubuntu1.2 [389 kB]
Fetched 389 kB in 0s (987 kB/s)
Selecting previously unselected package sudo.
(Reading database ... 225046 files and directories currently installed.)
Preparing to unpack .../sudo_1.8.16-0ubuntu1.2_amd64.deb ...
Unpacking sudo (1.8.16-0ubuntu1.2) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up sudo (1.8.16-0ubuntu1.2) ...
chown: changing ownership of '/etc/sudoers': Operation not permitted
dpkg: error processing package sudo (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
sudo
E: Sub-process /usr/bin/dpkg returned an error code (1)
root@tozen:/home/tozen#
Выхлоп идентичен.