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After installing updates 2 days ago, I got the screen below on startup. I don't know what a Citadel account is as I never had one!

I tried keying in my password but nothing happened (I tried different keyboards as well but still nothing is inputted). I also tried re-installing my OS but after a number of errors, an the 5 - 6 attempt I managed to get the install screen that stated that there was no OS detected. Obviously, formatting my computer is the last thing I want to do.

How can I restore my OS back to the way it was before installation? enter image description here

Mark J Galea
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3 Answers3

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  1. Boot with a USB - DVD in rescue mode.
  2. Mount the file system.
  3. Make a copy of your data. Backup it.
  4. Create new user, reboot again and try to login with this new user.
  5. If nothing work. Reinstall.
Albert1t0
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You could try the recovery mode of Ubuntu and drop to a root shell.

Follow the steps at https://wiki.ubuntu.com/RecoveryMode or look at the question How do I boot into a root shell? which is more detailed and with screenshots.

This root terminal you could use to access the system and back up all your important data.

You can also e.g. examine /var/log/apt/history.log which logs packages installed/updated/removed through apt and maybe revert recent installations.

To get a list of all installed packages, run dpkg -l | less, but it will be a very long list. Therefore we use the less viewer to get a scrollable list. You can narrow it down to only show lines containing a specific pattern like "citadel", use dpkg -l | grep -i "citadel" | less (-i for case-insensitive matching).

Remove strange packages with apt-get purge PACKAGENAME.

Please respond if you could follow any of these methods and what results you achieved. We can probably continue with further steps then.

Community
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Byte Commander
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Mark, I suspect that you have encountered a ransomware virus. Try booting from a DVD. Have a look at your hard drive. Are all the folders OK or do they have strange names? I suspect that they will be encrypted files containing all your data. Certainly, trying to reinstall the OS will fail as this action is blocked by the virus.

This vulnerability is very new on Linux. However, I understand that it is not a good one and that it is possible to enter an unencrypt key yourself and free up the machine. Unfortunately I have lost the article.

My advice is contact Ubuntu and ask advice as they must have encountered this by now. Alternately, search Google for Linux ransomware virus solution.

I really hope I am wrong but I suspect that I am right in interpreting your OS's symptoms.

Winlinuser
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