The Nusm virus is a STOP/DJVU family of ransomware-type infections. This virus encrypts your files (video, photos, documents) that can be tracked by a specific “.nusm” extension. It using a strong encryption method, which makes it impossible to calculate the key in any way.

Nusm uses a unique key for each victim, with one exception:

• If Nusm is unable to establish a connection to its command and control server (C&C Server) before starting the encryption process, it uses the offline key. This key is the same for all victims, which makes it possible in some cases to decrypt files encrypted during a ransomware attack.

Brendan SmithIT Security Expert

First, scan your PC with antivirus tool!

I will try to help you remove Nusm virus and will assist you to decrypt or restore encrypted files. The is an excellent way to deal with recognizing and removing threats - using Gridinsoft Anti-Malware. This program will scan your PC, find and neutralize all suspicious processes. DOWNLOAD NOWGridinsoft Anti-Malware 6-day trial available.
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There are several universal methods for recovering encrypted .nusm files, which will be demonstrated below. It is very important to read the entire instruction manual carefully and make sure to understand it all. Do not skip any steps, each of these steps is very important and must be completed by you.

Nusm virus

Nusm

🤔 Nusm virus is ransomware that originates from the DJVU/STOP family. Its primary purpose is to encrypt files that are important for you. After that ransomware virus asks its victims for a ransom fee ($490 – $980) in BitCoin.

The Nusm ransomware is a kind of threat that encrypted your documents and then forced you to pay to restore them. Note that Djvu/STOP ransomware family was first revealed and analyzed by virus analyst Michael Gillespie.

Nusm virus is similar to other representatives of DJVU ransomware like: PAHD, Ehiz, Igvm, Pcqq, Rejg. This virus encrypt all common file types and adds its own “.nusm” extension into all files. For example, the file “1.jpg”, will be amended into “1.jpg.nusm“. As soon as the encryption is accomplished, virus creates a specific message file “_readme.txt” and adds it into all folders that contain the modified files.

Name	Nusm Virus
Ransomware family1	DJVU/STOP2 ransomware
Extension	.nusm
Ransomware note	_readme.txt
Ransom	From $490 to $980 (in Bitcoins)
Contact	,
Detection3	Ransom:Win32/Avaddon.A!MTB, Win32/LockScreen.BQ, ATK/Shellter-AF
Symptoms	Encrypted most of your files (photos, videos, documents) and adds a particular “.nusm” extension; Can delete Volume Shadow copies to make victim’s attempts to restore data impossible; Adds a list of domains to HOSTS file to block access to certain security-related sites; Installs password-stealing Trojan on the system, like Azorult Spyware;
Fix Tool	To remove possible malware infections, scan your PC: GridinSoft Anti-Malware 6-day free trial available.

The image below gives a clear vision of how the files with the “.nusm” extension look like:

Encrypted files by NUSM Ransomware

This _readme.txt file asking payment is for restore files via decryption key:

_readme.txt (STOP/DJVU Ransomware) – The scary alert demanding from users to pay the ransom to decrypt the encoded data contains these frustrating warnings

The cryptography algorithm used by DJVU/STOP virus is AES-256. So, if your files got encrypted with an online decryption key, which is unique. The sad reality is that it is impossible to decrypt the files without the unique key.

In case if Nusm worked in online mode, it is impossible for you to gain access to the AES-256 key. It is stored on a distant server owned by the criminals who distribute the Nusm ransomware.

For receiving decryption key the payment should be $980. To obtain the payment details, the victims are encouraged by the message to contact the frauds by email ().

The message by the ransomware states the following information:

ATTENTION!
Don't worry, and you can return all your files!
All your files like photos, databases, documents, and other important are encrypted with the strongest encryption and unique key.
The only method of recovering files is to purchase a decrypt tool and unique key for you.
This software will decrypt all your encrypted files.
What guarantees you have?
You can send one of your encrypted files from your PC, and we decrypt it for free.
But we can decrypt only 1 file for free. The file must not contain valuable information.
You can get and look video overview decrypt tool:
The price of private keys and decrypt software is $980.
Discount 50% available if you contact us first 72 hours, that's the price for you is $490.
Please note that you'll never restore your data without payment.
Check your e-mail "Spam" or "Junk" folder if you don't get an answer in more than 6 hours.
To get this software you need writes on our e-mail:
Reserve an e-mail address to contact us:
Your personal ID:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

How did Nusm infect my computer?

Typically, ransomware developers distribute malware through untrustworthy software downloads, fake (unofficial) software updates, email spam, and system vulnerabilities (exploits).

Some examples of unreliable software download sources are peer-to-peer networks (for example, uTorrent, eMule, Deluge, BitTorrent, and others), so-called “free download sites” or sites for sharing files.

Using these sources, cybercriminals present their malware as legitimate and trick people into downloading and installing malware (or other unwanted applications).

Often, unofficial software update tools (fake updaters) are used to download and install malware instead of promised software updates. These tools are capable of exploiting vulnerabilities in legacy software.

Do not pay for Nusm!

_readme.txt file also indicates that the computer owners must get in touch with the Nusm representatives during 72 hours starting from the moment files were encrypted. On the condition of getting in touch within 72 hours, users will be granted a 50% rebate. Thus the ransom amount will be minimized down to $490). Yet, stay away from paying the ransom!

I strongly recommend that you do not contact these crooks and do not pay. The one of the most real working solution to recover the lost data – just using the available backups, or use NUSM File Decryption tool.

The peculiarity of all such viruses applies a similar set of actions for generating the unique decryption key to recover the ciphered data.

Thus, unless the ransomware is still under the stage of development or possesses some hard-to-track flaws, manually recovering the ciphered data is a thing you can’t perform. The only solution to prevent the loss of your valuable data is to make backups of your crucial files regularly.

Note that even if you do maintain such backups regularly, they ought to be put into a specific location without loitering, not being connected to your main workstation.

For instance, the backup may be kept on the USB flash drive or some alternative external hard drive storage. Optionally, you may refer to the help of online (cloud) information storage.

Needless to mention when you maintain your backup data on your common device, it may be similarly ciphered as well as other data.

For this reason, locating the backup on your main computer is surely not a good idea.

How To Remove Nusm Virus?

The is an excellent way to deal with recognizing and removing threats – using Gridinsoft Anti-Malware. This program will scan your PC, find and neutralize all suspicious processes">⁶.

1. Download Removal Tool.

   You can download GridinSoft Anti-Malware by clicking the button below:

   Download GridinSoft Anti-Malware

2. Run the setup file.

   When setup file has finished downloading, double-click on the setup-antimalware-fix.exe file to install GridinSoft Anti-Malware on your system.

   An User Account Control asking you about to allow GridinSoft Anti-Malware to make changes to your device. So, you should click “Yes” to continue with the installation.

3. Press “Install” button.

4. Once installed, Anti-Malware will automatically run.

5. Wait for the Anti-Malware scan to complete.

   GridinSoft Anti-Malware will automatically start scanning your PC for Nusm infections and other malicious programs. This process can take a 20-30 minutes, so I suggest you periodically check on the status of the scan process.

6. Click on “Clean Now”.

   When the scan has completed, you will see the list of infections that GridinSoft Anti-Malware has detected. To remove them click on the “Clean Now” button in right corner.

Trojan Killer for special instances

There is a minimal number of security tools that can be set up on USB drives, and antiviruses that can do so in most cases require obtaining quite an expensive license. For this instance, I can recommend you to use another solution of GridinSoft – Trojan Killer Portable. It has a 14-days cost-free trial mode that offers the entire features of the paid version ">⁷. This term will definitely be 100% enough to wipe malware out.

How To Decrypt .nusm Files?

The newest extensions released around the end of August 2019 after the criminals made changes. This includes Wrui, Lmas, Urnb, etc.

As a result of the changes made by the criminals, STOPDecrypter is no longer supported. It has been removed and replaced with the Emsisoft Decryptor for STOP Djvu Ransomware developed by Emsisoft and Michael Gillespie.

You can download free decryption tool here: Decryptor for STOP Djvu.

Download and run decryption tool.

Start downloading the decryption tool.

Make sure to launch the decryption utility as an administrator. You need to agree with the license terms that will come up. For this purpose, click on the “Yes” button:

As soon as you accept the license terms, the main decryptor user interface comes up:

Select folders for decryption.

Based on the default settings, the decryptor will automatically populate the available locations to decrypt the currently available drives (the connected ones), including the network drives. Extra (optional) locations can be selected with the help of the “Add” button.

Decryptors normally suggest several options considering the specific malware family. The current possible options are presented in the Options tab and can be activated or deactivated there. You may locate a detailed list of the currently active Options below.

Click on the “Decrypt” button.

As soon as yo add all the desired locations for decryption into the list, click on the “Decrypt” button in order to initiate the decryption procedure.

Note that the main screen may turn you to a status view, letting you know of the active process and the decryption statistics of your data:

The decryptor will notify you as soon as the decryption procedure is completed. If you need the report for your personal papers, you can save it by choosing the “Save log” button. Note that it is also possible to copy it directly to your clipboard and to paste it into emails or messages here if you need to do so.

The Emsisoft Decryptor might display different messages after a failed attempt to restore your nusm files:

How to Restore .nusm Files?

Nusm ransomware encryption mechanism feature is next: it encrypts every file byte-by-byte, then saves a file copy, deleting (and not overriding!) the original file. Hence, the file location information on the physical disk is lost, but the original file is not deleted from the physical disk. The cell, or the sector where this file was stored, can still contain this file, but it is not listed by the file system and can be overwritten by data that has been loaded to this disk after the deletion. Hence, it is possible to recover your files using special software.

Recovering your files with PhotoRec

PhotoRec is an open-source program, which is created for file recovery from damaged disks or for file recovery in case if they are deleted. However, as time has gone by, this program can recover the files of 400 different extensions. Hence, it can be used for data recovery after the ransomware attack

At first, you need to download this app. It is 100% free, but the developer states that there is no guarantee that your files will be recovered. PhotoRec is distributed in a pack with other utility of the same developer – TestDisk. The downloaded archive will have the TestDisk name, but don’t worry. PhotoRec files are right inside.

To open PhotoRec, you need to find and open “qphotorec_win.exe” file. No installation is required – this program has all the files it need inside of the archive, hence, you can fit it on your USB drive, and try to help your friend/parents/anyone who was been attacked by DJVU/STOP ransomware.

After the launch, you will see the screen showing you the full list of your disk spaces. However, this information is likely useless because the required menu is placed a bit higher. Click this bar, then choose the disk which was attacked by ransomware.

After choosing the disk, you need to choose the destination folder for the recovered files. This menu is located at the lower part of the PhotoRec window. The best desicion is to export them on USB drive or any other type of removable disk.

Then, you need to specify the file formats. This option is located at the bottom, too. As it was mentioned, PhotoRec can recover files of about 400 different formats.

Finally, you can start files recovery by pressing the “Search” button. You will see the screen where the results of the scan and recovery are shown.

Nusm files recovery guide

Frequently Asked Questions

🤔 How can I open “.nusm” files?

No way. These files are modified by ransomware. The contents of .nusm files are not available until they are decrypted.

🤔 Nusm files contain important information. How can I decrypt them urgently?

If your data remained in the .nusm files very valuable, you most likely made a backup copy.
If not, then you can try to restore them through the system function – Restore Point.
All other methods will require patience.

🤔 You have advised using GridinSoft Anti-Malware to remove Nusm. Does this mean that the program will delete my encrypted files?

Of course not. Your encrypted files do not pose a threat to the computer. What happened has already happened.

You need GridinSoft Anti-Malware to remove active system infections. The virus that encrypted your files is most likely still active and periodically runs a test for the ability to encrypt even more files. Also, these viruses install keyloggers and backdoors for further malicious actions (for example, theft of passwords, credit cards) often.

🤔 Nusm virus has blocked the infected PC: I can’t get the activation code.

In this situation, you need to prepare the memory stick with a pre-installed Trojan Killer.

🤔 Decryptor did not decrypt all my files, or not all of them were decrypted. What should I do?

Have patience. You are infected with the new version of STOP/DJVU ransomware, and decryption keys have not yet been released. Follow the news on our website.

We will keep you posted on when new Nusm keys or new decryption programs appear.

🤔 What can I do right now?

The Nusm ransomware encrypts only the first 150KB of files. So MP3 files are rather large. Some media players (Winamp, for example) may be able to play the files, but – the first 3-5 seconds (the encrypted portion) will be missing.

You can try to find a copy of an original file that was encrypted:

• Files you downloaded from the Internet that were encrypted, and you can download again to get the original.
• Pictures that you shared with family and friends that they can send back to you.
• Photos that you uploaded on social media or cloud services like Carbonite, OneDrive, iDrive, Google Drive, etc.)
• Attachments in emails you sent or received and saved.
• Files on an older computer, flash drive, external drive, camera memory card, or iPhone where you transferred data to the infected computer.

Also, you can contact the following government fraud and scam sites to report this attack:

• In the United States: On Guard Online;
• In Canada: Canadian Anti-Fraud Centre;
• In the United Kingdom: Action Fraud;
• In Australia: SCAMwatch;
• In New Zealand: Consumer Affairs Scams;
• In India, go to Indian National Cybercrime Reporting Portal.
• In France: Agence nationale de la sécurité des systèmes d’information;
• In Poland: KOMENDA GŁÓWNA POLICJI;
• In Portugal: Polícia Judiciária;
• In Italy: Polizia di Stato;
• In Spain: Cuerpo Nacional de Policía;
• In Germany: Bundesamt für Sicherheit in der Informationstechnik;
• In Ireland: An Garda Síochána;

To report the attack, you can contact local executive boards (A full list you can find here). For instance, if you live in USA, you can have a talk with FBI Local field office, IC3 or Secret Service.

Video Guide

If the guide doesn’t help you to remove Nusm virus, please download the GridinSoft Anti-Malware that I recommended. Also, you can always ask me in the comments for getting help. Good luck!

References

1. My files are encrypted by ransomware, what should I do now?
2. About DJVU (STOP) Ransomware.
3. Encyclopedia of threats.
4. Windows passwords vulnerability (Mimikatz HackTool):
5. GridinSoft Anti-Malware Review from HowToFix site:
6. More information about GridinSoft products:
7. Trojan Killer Review:

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