On 08.05.22 16:51, Sylvain Sécherre wrote:
I thought a lot about your answer and I feel a bit tricky... I
understand what you're writing but I don't know how to do this.
Do you think I can simply get rid of these rootkit? I've tried to move
the file "crontab" in a safe place and then reinstall the package cron.
The new "crontab" file seems to be the same as the previous since the
md5 are equal, but debcheckroot still throws an error for it...
Dear Sylvain
No, I don´t think you can get rid of the rootkit by reinstalling a
package. Usually rootkits are designed in a way that updating or
reinstalling packages doesn´t damage the rootkit. The best thing to do
is to reinstall new from scratch. In order to do this without
complications I have an own home partition that I can register and reuse
with /etc/fstab. If you don´t have that make a
cp -a /home /mnt/usbhdd/home
However that is not all you need to respect. Basically any infected
file can cause the rootkit to get reinstalled on your computer. That can
also be the case for hidden files in your home directory like
/home/sylvain/.*
I always do it like this:
cd /home/sylvain
ls -lad .[^.]*
mkdir /mnt/usbhdd/hidden-quarantine
mv .[^.]* /mnt/usbhdd/hidden-quarantine
the .[^.]* - expression works like this:
* first match anything that starts with a dot (under Linux hidden files
start with dots)
* second match a character that is not a dot [^.]: This excludes ..
which denotes the parent directory. This one should of course not be copied
* third match any from zero up to more characters: *
Make sure that you move away the hidden files before you copy your
home directory back.
Moving away hidden home directory files will also reset your Firefox
bookmarks and saved passwords. If you have progressed this far I can
tell you how to reinstall them - and under normal circumstances reusing
a database file should not cause a rootkit to reinstall. If you are very
thorough you can export the bookmarks as html and write down all saved
passwords on a sheet of paper. You need to know however that getting rid
of a rootkit with 100% certainty is hard since basically any binary file
can result in an attack vector.
If you have progressed this far, sure I am going to continue to help
you with setting up a new installation and rescuing bookmarks (at least
for FF).
Kind Regards,
Elmar
