Baaa virus: what it is and how to remove it

Some ransomware might modify Windows hosts file in order to prevent users from accessing certain websites online. For example, Djvu ransomware variants add dozens of entries containing URLs of security-related websites, such as 2-spyware.com. Each of the entries means that users will not be able to access the listed web addresses and will receive an error instead.

Here's an example of "hosts" file entries that were injected by ransomware:

In order to restore your ability to access all websites without restrictions, you should either delete the file (Windows will automatically recreate it) or remove all the malware-created entries. If you have never touched the "hosts" file before, you should simply delete it by marking it and pressing Shift + Del on your keyboard. For that, navigate to the following location:

C:\\Windows\\System32\\drivers\\etc\\

Important! →
Manual removal guide might be too complicated for regular computer users. It requires advanced IT knowledge to be performed correctly (if vital system files are removed or damaged, it might result in full Windows compromise), and it also might take hours to complete. Therefore, we highly advise using the automatic method provided above instead.

Step 1. Access Safe Mode with Networking

Manual malware removal should be best performed in the Safe Mode environment.

Windows 7 / Vista / XP

1. Click Start > Shutdown > Restart > OK.
2. When your computer becomes active, start pressing F8 button (if that does not work, try F2, F12, Del, etc. - it all depends on your motherboard model) multiple times until you see the Advanced Boot Options window.
3. Select Safe Mode with Networking from the list.

Windows 10 / Windows 8

1. Right-click on Start button and select Settings.
   
   
2. Scroll down to pick Update & Security.
   
3. On the left side of the window, pick Recovery.
4. Now scroll down to find Advanced Startup section.
5. Click Restart now.
   
6. Select Troubleshoot.
7. Go to Advanced options.
8. Select Startup Settings.
9. Press Restart.
10. Now press 5 or click 5) Enable Safe Mode with Networking.

Step 2. Shut down suspicious processes

Windows Task Manager is a useful tool that shows all the processes running in the background. If malware is running a process, you need to shut it down:

1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
2. Click on More details.
   
3. Scroll down to Background processes section, and look for anything suspicious.
4. Right-click and select Open file location.
   
5. Go back to the process, right-click and pick End Task.
   
6. Delete the contents of the malicious folder.

Step 3. Check program Startup

1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
2. Go to Startup tab.
3. Right-click on the suspicious program and pick Disable.
   
   

Step 4. Delete virus files

Malware-related files can be found in various places within your computer. Here are instructions that could help you find them:

1. Type in Disk Cleanup in Windows search and press Enter.
   
   
2. Select the drive you want to clean (C: is your main drive by default and is likely to be the one that has malicious files in).
3. Scroll through the Files to delete list and select the following: Temporary Internet Files
   Downloads
   Recycle Bin
   Temporary files
4. Pick Clean up system files.
   
   
5. You can also look for other malicious files hidden in the following folders (type these entries in Windows Search and press Enter): %AppData%
   %LocalAppData%
   %ProgramData%
   %WinDir%

After you are finished, reboot the PC in normal mode.

Since many users do not prepare proper data backups prior to being attacked by ransomware, they might often lose access to their files permanently. Paying criminals is also very risky, as they might not fulfill the promises and never send back the required decryption tool.

While this might sound terrible, not all is lost - data recovery software might be able to help you in some situations (it highly depends on the encryption algorithm used, whether ransomware managed to complete the programmed tasks, etc.). Since there are thousands of different ransomware strains, it is immediately impossible to tell whether third-party software will work for you.

Therefore, we suggest trying regardless of which ransomware attacked your computer. Before you begin, several pointers are important while dealing with this situation:

• Since the encrypted data on your computer might permanently be damaged by security or data recovery software, you should first make backups of it - use a USB flash drive or another storage.
• Only attempt to recover your files using this method after you perform a scan with anti-malware software.

Install data recovery software

1. Download .
2. Double-click the installer to launch it.
   
3. Follow on-screen instructions to install the software.
4. As soon as you press Finish, you can use the app.
5. Select Everything or pick individual folders where you want the files to be recovered from.
6. Press Next.
7. At the bottom, enable Deep scan and pick which Disks you want to be scanned.
8. Press Scan and wait till it is complete.
9. You can now pick which folders/files to recover - don't forget you also have the option to search by the file name!
10. Press Recover to retrieve your files.

If your computer got infected with one of the Djvu variants, you should try using Emsisoft decryptor for Djvu/STOP. It is important to mention that this tool will not work for everyone - it only works if data was locked with an offline ID due to malware failing to communicate with its remote servers.

Even if your case meets this condition, somebody from the victims has to pay criminals, retrieve an offline key, and then share it with security researchers at Emsisoft. As a result, you might not be able to restore the encrypted files immediately. Thus, if the decryptor says your data was locked with an offline ID but cannot be recovered currently, you should try later. You also need to upload a set of files - one encrypted and a healthy one to the company's servers before you proceed.

• Download the app from the official Emsisoft website.
• After pressing Download button, a small pop-up at the bottom, titled decrypt_STOPDjvu.exe should show up - click it.
  
• If User Account Control (UAC) message shows up, press Yes.
• Agree to License Terms by pressing Yes.
  
  
• After Disclaimer shows up, press OK.
• The tool should automatically populate the affected folders, although you can also do it by pressing Add folder at the bottom.
  
• Press Decrypt.
  
  

From here, there are three available outcomes:

1. "Decrypted!" will be shown under files that were decrypted successfully - they are now usable again.
2. "Error: Unable to decrypt file with ID:" means that the keys for this version of the virus have not yet been retrieved, so you should try later.
3. "This ID appears to be an online ID, decryption is impossible" - you are unable to decrypt files with this tool.

Some ransomware strains aim to infect not only one computer but hijack the entire network. As soon as one of the machines is infected, malware can spread via the network and encrypt files everywhere else, including Network Attached Storage (NAS) devices. NAS devices are commonly compromised via reused administrator credentials and remote access services, and attackers may also delete existing snapshots. If your computer is connected to a network, it is important to isolate it to prevent re-infection after ransomware removal is complete.

In modern environments, ransomware often spreads using stolen credentials, remote management tools, VPN connections, and cloud synchronization services, not only through shared network drives.

The easiest way to disconnect a PC from everything is simply to plug out the ethernet cable. This does not disconnect wireless networks, VPN connections, or cloud services, which must also be disabled separately. However, in the corporate environment, this might be extremely difficult to do (also would take a long time). In many organizations, devices are centrally managed, and network isolation is typically performed by IT or security teams using endpoint security or device management tools. The method below will disconnect from all the networks, including local and the internet, isolating each of the machines involved.

On modern Windows systems, network connections can also be disabled through the Settings app or automatically isolated using endpoint detection and response (EDR) tools.

• Type in Control Panel in Windows search and press Enter
• Go to Network and Internet
• Click Network and Sharing Center
• On the left, pick Change adapter settings
• Right-click on your connection (for example, Ethernet), and select Disable
• Confirm with Yes.

If you are using some type of cloud storage you are connected to, you should disconnect from it immediately. It is also advisable to disconnect all the external devices, such as USB flash sticks, external HDDs, etc. Once the malware elimination process is finished, you can connect your computers to the network and internet, as explained above, but by pressing Enable instead. Before reconnecting, credentials should be reset, persistence mechanisms checked, and backups verified to ensure reinfection does not occur.