If your computer has been infected with a virus, you should do two things: First, disconnect your computer from the network immediately and remove any external storage media. Second, pull the following disaster recovery plan out of the drawer and go through it step by step.
It’s really annoying when your computer gets a virus. Especially if you have anti-virus software installed. Of course, you can first try to scan the PC with the anti-virus software. However, the malware managed to infiltrate your system anyway, so it's unlikely that a scan will be able to detect the virus. You can now either consult an IT expert or try running through the following checklist:
1. Disconnect your computer from the network (Internet) to prevent further spread or activity of the malware.
2. Disconnect all external storage media such as hard drive, USB stick or smartphone to prevent further infestation.
3. Get yourself a coffee because the following steps take some time.
4. Scan the computer using anti-virus software in one of the following ways:
Launch Windows and press the F8 key to enter Safe Mode. Now run a full scan. Stay offline.
A specialised rescue USB stick or DVD offer greater prospects for success. If you launch the scan with one of these media, the virus will not become active and can be detected more easily. You can create a rescue medium yourself, for example with the Kaspersky Rescue Disk or Desinfec't from German IT publisher Heise.
5. If the scan detects viruses in the system, place them in quarantine. This will store the virus program in a safe location where it will no longer be active. This can be useful to find out if the virus has infected system files. If the malware is in a mail attachment, you can delete it directly.
6. Scan external data carriers that were attached to the computer at the time of the attack. It's best to use a rescue medium.
7. You might want to grab another coffee because, to be on the safe side, you should now reinstall the computer. Format the hard drive and reinstall Windows and all the other applications.
8. Change your passwords. If the virus gained access to your credentials, your passwords are no longer secure.