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What is ransomware?

Ransomware stops you from using your PC. It holds your PC or files for ransom.

Some versions of ransomware are called "FBI Moneypak" or the "FBI virus" because they use the FBI's logos.

What does it look like and how does it work?

There are different types of ransomware. However, all of them will prevent you from using your PC normally, and they will all ask you to do something before you can use your PC.

They can:

  • Prevent you from accessing Windows.

  • Encrypt files so you can't use them.

  • Stop certain apps from running (like your web browser).

They will demand that you do something to get access to your PC or files. We have seen them:

  • Demand you pay money.

  • Make you complete surveys.

Often the ransomware will claim you have done something illegal with your PC, and that you are being fined by a police force or government agency.

These claims are false. It is a scare tactic designed to make you pay the money without telling anyone who might be able to restore your PC.

There is no guarantee that paying the fine or doing what the ransomware tells you will give access to your PC or files again.

Prevalent ransomware

Locky  and Cerber are two of the most prevalent and dangerous ransomware currently active.

Read more about Locky in the following blog:

Cerber is also active at the moment and plays a synthesized text-to-speech file when it encrypts files on an infected PC. You can read more about Cerber in out blog:

FakeBsod has emerged as a new prevalent ransomware family since it was first detected in September 2015, as shown in Figure 1. FakeBsod was the second most detected malware in the top ten list of prevalent ransomware, with 21 percent of detections.

Figure 1. Top 10 Ransomware (June to November 2015)

FakeBsod was responsible for 17 percent of the top ten ransomware infections detected by Microsoft security products during November 2015.

Figure 2. Top 10 Ransomware (November 2015)

FakeBsod uses a malicious piece of JavaScript code to lock your web browser and show a fake warning message when you visit a compromised or malicious webpage. The warning message tells you to “contact Microsoft technicians” about an “Error 333 Registry Failure of operating system – Host: Blue screen Error 0x0000000CE”. If you call the phone number in the message you will be asked to pay money to “fix” the issue.

An example of the fake warning message is shown in Figure 3:

Figure 3: Message used by FakeBsod to lock your web browser

You can regain control of your web browser without paying anything by closing the warning message using the Task Manager.

When you reopen your browser, make sure you don't click 'restore previous session'.

Read more about this threat in the Ransom:JS/FakeBsod.A description.

Examples of ransomware

Frequently asked questions

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  • No. These warnings are fake and have no association with legitimate authorities. The message uses images and logos of legal institutions to make the it look authentic.

  • We don’t recommend you pay. There is no guarantee that handing over the ransom will give you access to your files again. Paying the ransom could also make you a target for more malware.

  • How to recover your files depends on where your files are stored and what version of Windows you are using.

    Before you try to recover files, you should use Windows Defender Offline to fully clean your PC.

    For Microsoft Office files stored, synced, or backed up to OneDrive

    For files on your PC

    • You need to have turned on File History (in Windows 10 and Windows 8.1) or System Protection for previous versions (in Windows 7 and Windows Vista) before you were infected. In some cases, these might have been turned on already by your PC manufacturer or network administrator.

    • Some ransomware will also encrypt or delete the backup versions of your files. This means that even if you have enabled File History, if you have set the backup location to be a network or local drive your backups might also be encrypted. Backups on a removable drive, or a drive that wasn't connected when you were infected with the ransomware, might still work.

    • See the Windows Repair and recovery site for help on how to enable file recovery for your version of Windows.

    If you've been infected by the Crilock family of ransomware (also called CryptoLocker), you might be able to use the tool mentioned in the MMPC blog:

  • You should contact your bank and your local authorities, such as the police. If you paid with a credit card, your bank may be able to block the transaction and return your money.

    The following government-initiated fraud and scam reporting websites may also help:

    If your country or region isn't listed here, we encourage you to contact your country's federal police or communications authority.

    For general information on what to do if you have paid, see:

  • Your IP address is not usually hidden, and there are lots of tools online that will get it for you. It’s likely they used such a tool.

  • In most instances ransomware is automatically downloaded when you visit a malicious website or a website that's been hacked.

    For other ways malware, including ransomware, gets on your PC, see:

  • You should:

    You can backup your files with a cloud storage service that keeps a history or archive of your files, such as OneDrive which is now fully integrated into Windows 10 and Windows 8.1, and Microsoft Office.

    After you've removed the ransomware infection from your computer, you can restore previous, unencrypted versions of your Office files using "version history".

    See the question "How do I get my files back?" above for more help on how to use this feature in OneDrive.

    For more tips on preventing malware infections, including ransomware infections, see:

  • Microsoft doesn’t recommend you pay the fine. There is no guarantee that paying the ransom will give you access to your files.

    If you've already paid, see the question "What should I do if I've paid?" above.

    How to remove the ransomware depends on what type it is.

    If your web browser is locked

    You can try to unlock your browser by using Task Manager to stop the web browser's process:

    • Open Task Manager. There are a number of ways you can do this:

      • Right-click on an empty space on the taskbar and click Task Manager or Start Task Manager.

      • Press Ctrl+Shift+Esc.

      • Press Ctrl+Alt+Delete.

    • In the list of Applications or Processes, click on the name of your web browser.

    • Click End task. If you are asked if you want to wait for the program to respond, click Close the program.

    • In some workplaces, access to Task Manager may be restricted by your network administrator. Contact your IT department for help.

    When you open your web browser again, you may be asked to restore your session. Do not restore your session or you may end up loading the ransomware again.

    See the question “How do I protect myself from ransomware” above for tips on preventing browser-based ransomware from running on your PC.

    If your PC is locked

    • Method 2: Use Windows Defender Offline

      Because ransomware can lock you out of your PC, you might not be able to download or run the Microsoft Safety Scanner. If that happens, you will need to use the free tool Windows Defender Offline:

      See our advanced troubleshooting page for more help.

    Steps you can take after your PC has been cleaned

    Make sure your PC is protected with antimalware software.

    Microsoft has free security software that you can use:

    If you don't want to use Windows Defender or Microsoft Security Essentials, you can download other security software from another company. Just make sure it is turned on all the time, fully updated, and provides real-time protection.

Top ransomware