How to Remove Nobu Ransomware (.nobu Files)

Nobu ransomware is a file-coder virus that is part of STOP/DJVU malware family. It can access the computer via various penetration methods, especially through the spam email campaign. Once Nobu enters the computer, it is able to lock the files using a high level of encryption that is quite impossible to decipher without the corresponding decryption software. Then, Nobu ransomware releases a payment request via its ransom note file generated in the same folder as the encrypted data.

How does the Nobu virus infect the computer?

This ransomware is part of the notorious family of malware, STOP/DJVU. Like older variants such as Weui, Sglh, and Lisp that use different scheming ways to enter the computer, there is no other way for Nobu to spread but to adopt the same techniques.

Nobu ransomware is seen as being deployed quickly and easily via mass-mailing campaigns. This is a technique where the virus is carried out on the email message as an attachment. By masquerading as an official document file from a reputable organization or business entity, it can easily persuade the recipients to open the attached file. In this case, Nobu ransomware initializes the computer infection and launches a file-coding operation.

Next to spam emails, cracked software or any kind of malicious file installers are observed as another co-conspirator to widely spread Nobu ransomware. Programs that computer users may download intentionally from file-sharing sites, software piracy platforms, or freeware sites could contain malicious code that may lead to a Nobu ransomware infection. Therefore, avoid the mentioned sites and any obtainable apps they are offering.

Nobu File Encryption and Decryption

When Nobu ransomware infects the computer, it will drop several files in the System folder. The virus also creates an auto-start technique to run the malicious code during Windows boot-up. Next, it will communicate with the remote server to accept commands. A public key is also requested from the server that Nobu will use during file decryption.

The focal point of the attack is file encryption, where the virus is using a complex method to make the important user’s files inaccessible. Apart from encryption techniques, data is also appended with a nobu file extension. As a result, the ordinary file image.jpg will turn into image.jpg.nobu after the encryption process.

As with the entire ransomware attack, the hackers will demand ransom payments from victims if they want to recover the encrypted data. In this particular case, the people who created Nobu ransomware are demanding $980. This price and the discounted value are clearly stipulated in the ransom note file. Please see the screenshot image of the ransom note below.

Screenshot of Nobu ransom note

Technical Details
Threat Name Nobu Ransomware, STOP, DJVU
Threat Type Crypto-virus, File Locker, and Encryption Virus
Encryption Method AES-256 combined with RSA-1024 Asymmetric Encryption
File Extension .nobu
Ransom Amount $980 (worth of Bitcoin)
Ransomware Note File _readme.txt
Attacker’s email helpmanager@mail.ch
restoremanager@airmail.cc
Discovered by @Emm_ADC_Soft
Virus Alias AVG : Win32:DropperX-gen
Avira : TR/AD.InstaBot.gzfzd
BitDefender : Gen:Variant.Midie.77297
Cyren: W32/Kryptik.COL.gen!Eldorado
Emsisoft : Gen:Variant.Midie.77297 (B)
ESET-NOD32 : A Variant Of Win32/Kryptik.
F-Secure : Trojan.TR/AD.InstaBot.gzfzd
Fortinet : PossibleThreat.ARN.M
Ikarus : Trojan.Win32.Ranumbot
Kaspersky : HEUR:Exploit.Win32.Shellcode.gen
Malwarebytes : Trojan.MalPack
McAfee: GenericRXMV-JU!F8EF98BBAFF6
Microsoft: Trojan:Win32/Glupteba.NA!MTB
Panda : Trj/Downloader.FUM
Sophos : ML/PE-A
Symantec : ML.Attribute.HighConfidence
TrendMicro : TROJ_GEN.R002C0DL420
Webroot : W32.Trojan.Gen

Backup your files

One important step before proceeding with the procedures below is to backup your files. Ransomware are not the same. Each has its unique sets of payloads aside from encrypting the files with complex method. Others tend to delete the infected files after certain period, while others keep them concealed on hidden places. In addition, ransomware decryption tools are not guaranteed to be perfect, there are instances that files suffer from damages during the decryption process.

So, create a backup copy of your entire Nobu encrypted files right now.

Nobu Ransomware Removal Guide

First thing to do is remove the Nobu virus before attempting the decryption. Remember that as long as the ransomware is active, it will repeatedly encrypt the files on the compromised computer.

Infection of Nobu ransom virus is dangerous to the system because it can inject files that runs each time Windows starts. To prevent the malicious files from loading, Windows operating system must run with minimal process and it can be done through SafeMode With Networking.

Quick Fix - Scan the PC with Combo Cleaner for Windows

Combo Cleaner is a trusted PC security and optimization tool equipped with powerful virus and malware detection engine. This program can get rid of ransomware like Nobu through this procedure.

1. Download the application from the following page:

2. Save the file to your preferred location.

3. Double-click the downloaded file CCSetup.exe and install with the default settings.

CC for Windows Installation

4. At the end of the setup process, click Finish to run Combo Cleaner.

5. The tool will update the signature file, please wait for this process to complete.

6. To begin checking for threats like Nobu ransomware, click on the Start Scan button. Wait for this scan to finish.

CC for Windows Start Scan

7. At the end of the scan process, click on Remove all threats to delete Nobu ransomware including all malicious objects from the computer.

Free features of Combo Cleaner for Windows include Disk Cleaner, Big Files finder, Duplicate files finder, and Uninstaller. To use antivirus, privacy scanner, and to delete identified threats, users have to upgrade to a premium version.

Please continue with the succeeding removal procedures if your are comfortable to manually get rid of the threat and malicious items linked with it.

Step 1 : Start Windows in Safe Mode With Networking

The method of running Windows in Safe Mode before running a virus scan is effective in getting rid of Nobu. This process can prevent most viruses and malware from loading, making it easier to detect and remove them.

1. On the Windows Search bar, please type msconfig.

Screenshot of MSConfig Command

2. Select and open System Configutation on the list of found results.

3. Once you are in the System Configuration window, go to the Boot tab.

Screenshot of SafeBoot

4. Under the Boot Options area, please check Safe Boot and select Network. This will allow Windows to boot in Safe Mode with Networking.

5. Lastly, click on Apply and OK to save the changes.

6. Please restart Windows.

Do not forget to restore the normal boot process of Windows after running the virus scan. Simply repeat the method above, and this time, uncheck the Safe Boot option to run Windows normally.

Step 2 : Scan the Computer with Sophos Antivirus

Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Nobu virus. Aside from our suggested tool, you may also run your own security program.

To remove Nobu ransomware automatically, scanning the computer with this efficient anti-malware tool is suggested. This scanner does not just uncover known threats like viruses or malware, it is also effective in discovering hazardous ransomware like Nobu.

1. Download Sophos Virus Removal Tool from the link below. Save the file on your computer where you can easily access it.

2. Once the download completes, browse the location of the file. Double-click to run the program and begin the install process.

3. On first windows of installation wizard, click Next to continue. Then, it will display the program’s License Agreement. You need to Accept the terms in order to proceed. If Windows prompts for User Account Control, please click Yes to proceed.

Screenshot of Sophos EULA Page

4. On succeeding windows, click Next or Continue to carry on with the installation. After completing the installation process, Launch Sophos Virus Removal Tool.

5. Internet connection is required when running this virus scanner in order to download important updates. Make sure that everything is up-to-date to effectively remove Nobu ransomware and other relevant viruses.

6. Click the Start Scanning button to inspect the computer. This will check the system for presence of malicious objects, malware, and viruses. The tool reveals items that were found linked to Nobu ransomware and other suspicious entities. Be sure to remove all identified threats.

Screenshot of Sophos Virus Scan

The above procedures should have totally eliminated Nobu ransomware. However, if you found that there are still remnants of the virus, please proceed to succeeding procedures below.

Step 3 : Double Check with Windows Security Apps

Microsoft Windows has a built-in security application that you can use to double-check if your computer is still infected with Nobu. For Windows 10/11 users, please run Windows Security.

Windows 10 / 11 Instructions:

Windows Security is a free tool that was built to help you remove Nobu, viruses, and other malicious items from Windows 10/11 systems. Follow these procedures to scan your computer with the tool:

1. Tap or click the Search charm, search for Windows Security, and then open the application.

Image of Windows Security Search

2. On the Home tab, click Virus and threat protection from the sidebar.

3. On the main window, click on Scan Options. Then, click on Full Scan button.

Image of Scan Options

4. Lastly, click on the Scan now button to start scanning for the presence of Nobu. The process may take a while to complete.

5. After the scan, Delete/Quarantine identified threats, whether they were relevant to Nobu or not. You may now restart Windows to complete the virus removal process.

For older versions of Windows, you can scan the computer for free with the Microsoft Malicious Software Removal Tool (MSRT 64-Bit). It is a stand-alone virus scanner tool that targets prevalent malware groups.

Recover Files from Nobu Ransomware Infection

On this section, we will provide ways to decrypt files infected with Nobu ransomware. Aside from dedicated decryption software and common tools, other options for file recovery are provided. As much as we can, we will update this area whenever there is new and more suitable decryption tool was made available.

Decrypting Nobu infected files with Emsisoft Tools

This service from Emsisoft is helpful in unlocking encrypted files without paying the ransom. The page provides the list of ransomware decryption tools. All you have to do is look for the specific tool and start recovering the Nobu encrypted file.

Option: Use ShadowExplorer to restore files encrypted by Nobu Ransomware

ShadowExplorer depends on the presence of System Protection on every drive from which you wish to retrieve data. Furthermore, it is crucial that System Protection is enabled prior to any event that requires file recovery. It is worth noting that Windows automatically enables System Protection solely on the system partition (C). 

ShadowExplorer is taking advantage of shadow copy created by Windows system. This tool allows you to retrieve older version of files before it was encrypted by Nobu ransomware.

1. Download ShadowExplorer from the official web site.

2. Install the program with the default settings.

3. The program should run automatically after installation. If not, double-click on ShadowExplorer icon.

4. You can see the drop-down list on top of the console. Please select proper drive and the most recent point-in-time shadow copies of files you wish to restore prior to Nobu ransomware infection.

Screenshot of ShadowExplorer

5. Right-click on the Drive, Folder, or File you wish to restore and click Export...

6. Lastly, ShadowExplorer will prompt for location where you want to save the copy of recovered files.

How to protect the computer from Nobu ransomware?

After the removal of the ransomware, it is important to prevent similar incident from happening again. In order to protect the computer effectively, computer user must know how Nobu ransomware was able to infect the computer. To minimize the possible infection, staying away from the common sources of this virus is crucial.

How Nobu ransomware can infect your computer?

The method of infecting the computers was found to be similar as other common viruses. Though, ransomware like Nobu is seen to have efficient deployment via spam email messages, web injectors, malicious software installers, misleading online advertisements, and through another virus infection.

Once the virus is executed, it immediately infects the system. Then, Nobu ransomware communicates to remote server so that unique key can be generated for the specific computer. After acquiring the key, it starts to decrypt target files using a complex method that is almost unbreakable. On the last stage of the attack, Nobu ransomware demands for ransom money as payment for the decryption tool. To further understand the attack scheme, we have included an infographic below.

Infographic image of ransomware attack stages
You can print, download, or share the infographic by clicking the image.

Securing the computer against ransomware attack

Do a Regular File Back-up - Always backup your data on a separate storage devices such as external hard drives, optical discs, or online backup services.

Keep Your Software Updated - Make sure that you have the latest software updates especially on the operating system. Recent updates often contain vital security patches to help protect the computer against all forms of threats.

Install a Security Program - Protect the computer with effective anti-virus application using efficient real-time scanning. Regularly run a complete scan to check the computer for presence of malware.

Protect your files with Controlled Folder Access (Windows 10/11)

For Windows 10/11 users, aside from protecting the computer using anti-virus or anti-malware programs, one way to protect against ransomware attack is by using Controlled Folder Access. This feature of Windows Defender Security Center may not prevent the Nobu ransomware infection, but it can protect the folder and files in general. Follow the steps to enable Controlled Folder Access in Windows 10/11.

1. Go to Windows Taskbar and search for Windows Defender Security Center.

2. Open Windows Defender Security Center and click on Virus & Threat Protection icon.

Virus and Threat Protection

3. On next window, please click on Ransomware Protection.

4. Under Controlled Folder Access section, switch the slider to On. That will enable the feature and protect the folder against Nobu virus or any type of ransomware.

Controlled Folder Access

5. Click on Protected Folders link to include additional folders. Make sure that folders where important files are located should be included in the list.

Include Your Protected Folder

Troubleshooting Guide

Certain programs maybe blocked by Controlled Folder Access feature. To fix the issue, simply have the specific program to be white listed.

1. Under Protected Folders, click Allow an app through controlled folder access.

2. Next, click the Add an allowed app and include the target executable file.

This Controlled Folder Access feature is one way to protect files against Nobu ransomware. Other important things to do in keeping files safe against ransomware is through early prevention like keeping programs updated, install an efficient security program, an do regular file backup on a separate media drive.

Tutorial video to remove Nobu

About the author

2 thoughts on “How to Remove Nobu Ransomware (.nobu Files)”

  1. Hi, can you help me please. I still can’t remove that Nobu virus yet even I did so your step. If you don’t mind, can you teach personally to remove the virus? Thank You.

  2. Khushairi, if the recommended app didn’t help to remove Nobu virus, you can use other antivirus as alternative like Norton Power Eraser, Kaspersky, Avast, Sophos, and similar free scanners. Run the scan in Safemode.

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