New instal­la­tion Win­dows 10

Your PC has become infected with mal­ware. You don’t know how to cor­rectly rein­stall your system? The fol­lowing step-by-step instruc­tions will help you to rein­stall your PC and at the same time reduce the risk of a new infec­tion.

We have tried to draw up as gen­er­ally applic­able a set of instruc­tions for pri­vate users as pos­sible. Of course the steps required may differ in spe­cific cases.

These instruc­tions are based on a Win­dows 10 Pro 64 bit edi­tion, but also apply to 32 bit ver­sions.

To be able to prop­erly rein­stall your system in accor­dance with these instruc­tions, you will need the Win­dows 10 instal­la­tion CD plus an external storage medium to back up your data.

Step 1: Dis­con­nect your PC from the net­work

  • If your PC is con­nected to the net­work via a cable, simply pull out the net­work plug.
  • In case you are using a wire­less net­work (WLAN), you should acti­vate the flight mode (click the net­work symbol at the bottom right of the taskbar, → click the flight mode button).

Step 2: Backing up per­sonal data

  • With the «Shift» key pressed and held down, con­nect an external storage medium, and back up your per­sonal data. Do not use a «normal» back-up medium to do so, but a new, com­pletely blank one if pos­sible.
    PLEASE NOTE: Mal­ware on your PC can lead to your external storage medium and all data stored on it becoming infected too. Mal­ware specif­i­cally uses the Autorun func­tion to spread via external storage media (USB stick etc.). It is rel­a­tively simple to tem­porarily deac­ti­vate this Autorun func­tion. To do so, press and hold the «Shift» key on your key­board. Then con­nect the external storage medium to your com­puter and only let go of the «Shift» key a short time later. In this case, the «Shift» key pre­vents Win­dows from auto­mat­i­cally exe­cuting pro­grams and files on the external storage medium.

Step 3: Cleaning the Master Boot Record (MBR)

Cer­tain com­puter viruses will infil­trate the so-called Master Boot Record (MBR) of your PC. For this reason, this should be rewritten and cleaned this way. Use the «bootrec.exe» utility in the Win­dows restore envi­ron­ment to do so.

  • Insert your Win­dows 10 instal­la­tion CD into your drive and restart your PC.
  • If your PC does not boot from the CD inserted after this restart, set the CD drive as the first device in the PC BIOS (see main­board manual). Alter­na­tively, press the «F8» func­tion key straight after starting the PC. This will take you to the boot man­ager where you can select the CD drive.
  • Press a key when you are asked to do so.
  • Select an instal­la­tion lan­guage, time and cur­rency format, key­board or method of entry, and then click Con­tinue.
  • Click on Com­puter repair options at the bottom left.
  • Click Trou­bleshooting.
  • Click Advanced Options.
  • In the Advanced Options dia­logue box, click Com­mand prompt.
  • Enter «bootrec.exe /fixmbr» and then press the Enter key. This will restore the MBR (thus deac­ti­vating the MBR rootkit func­tion­ality of any mal­ware).
  • Close the Com­mand prompt and use Shut down to close your PC down. Leave the Win­dows 10 instal­la­tion CD in the drive.

Step 4: Rein­stal­la­tion of Win­dows 10

  • Restart your PC.
  • If your PC does not boot from the CD inserted after this restart, set the CD drive as the first device in the PC BIOS (see main­board manual). Alter­na­tively, press the «F8» func­tion key straight after starting the PC. This will take you to the boot man­ager where you can select the CD drive.
  • Press a key when you are asked to do so.
  • Select an instal­la­tion lan­guage, a time and cur­rency format, a key­board or method of entry, and then click Con­tinue.
  • Now you need to click on Install now.
  • In the course of instal­la­tion, please select Custom: Install Win­dows only (advanced) as type of instal­la­tion required.
  • You can now delete, newly create and format par­ti­tions.
    WARNING: When you delete or format a par­ti­tion, all data on the par­ti­tion will be lost!
    PLEASE NOTE: To make sure there is no mal­ware present on your PC any longer, you must delete the existing par­ti­tions and create them once again. After­wards, the newly cre­ated par­ti­tions should be for­matted. Please also note that there may be a recovery par­ti­tion cre­ated by the man­u­fac­turer present. This should not be deleted or for­matted.
  • To con­tinue with the Instal­la­tion in the selected par­ti­tion, click Con­tinue.
    WARNING: Once the system reboots, a screen enti­tled «Get going fast» appears. You should not click on Use express set­tings here!
  • Click Cus­tomize set­tings at the bottom left.
    PLEASE NOTE: As long as you choose your set­tings by selecting the above, you can pre­vent Win­dows trans­mit­ting too many data to Microsoft which you don’t want trans­mitted to them. On the fol­lowing three pages, you should there­fore switch all set­tings to «off». With one excep­tion: On the third page, you should use set­ting «User SmartScreen online ser­vice to help pro­tect against mali­cious con­tent and down­loads in sites loaded by Win­dows browsers and Store apps.» to «On», since this SmartScreen filter serves to block web­sites and down­loads con­taining mal­ware. You can find our check-list with addi­tional useful infor­ma­tion on pri­vacy under Win­dows 10 here.
  • Finish installing Win­dows 10 with the rec­om­mended set­tings.
  • Recon­nect your PC to the Internet (insert net­work plug).
  • Update your oper­ating system by clicking the mag­ni­fying glass at the bottom left in the task bar and entering «Win­dows update» there. Now click Look for updates and do the same again in the next window. Updates will now be installed auto­mat­i­cally.

Step 5: Installing antivirus soft­ware

  • Install antivirus soft­ware from a trust­worthy source and update this using the inte­grated update func­tion.
    PLEASE NOTE: A list of rec­om­mended antivirus soft­ware can be found here.

Step 6: Installing and updating pro­grams

  • Install the required pro­grams. Update all pro­grams, and acti­vate the auto-update func­tion wher­ever pos­sible.
    PLEASE NOTE: Please make sure to only install pro­grams from trust­worthy sources (e. g. man­u­fac­turer down­load sites or soft­ware archives such as PCtipp, Heise etc.).

Step 7: Scan­ning data

  • Hold down the «shift» key and con­nect the external storage medium with the data backed up pre­vi­ously to your PC.
    PLEASE NOTE: In case mal­ware was copied to the external storage medium when backing up your data, your PC can become rein­fected! To pre­vent this, if pos­sible, it is manda­tory to hold down the «Shift» key when con­necting the external storage medium (see note under step 2).
  • Scan the whole system and the external storage medium using the antivirus soft­ware installed pre­vi­ously. In case any infected files are found, you should ask to clean or delete them!
    PLEASE NOTE: A better, yet more elab­o­rate alter­na­tive to scan­ning via the newly installed system would be to check your external storage medium via a bootable live CD or from another oper­ating system (e. g. Linux, macOS).

Step 8: Restoring data

  • Restore your backed-up data from the external storage medium to the PC.

Step 9: Other vital things to do!

  • As mal­ware very fre­quently cap­tures user names and pass­words nowa­days, you should make sure to change all pass­words on your system itself, but also all pass­words to log into any web­sites (e. g. e-banking, e-mail access, Face­book etc.).
  • In addi­tion you should closely check your e-banking and credit card state­ments.

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