Remove NUSM Ransomware Virus (DECRYPT .nusm FILES)
NUSM ransomware is a new variant of STOP/DJVU virus
Contents
NUSM ransomware is a file-encrypting computer virus from STOP/DJVU malware family. The malicious program is designed to use RSA Salsa 20 algorithm when encrypting all files on the target computer and add .nusm extension after the real file extension. For example, a file originally called 1.jpg becomes 1.jpg.nusm after the encryption. Once all target files become modified, the virus drops _readme.txt notes in every computer folder. All of these notes contain an identical message that says the victim has to pay money for file decryption software. The attackers behind this attack suggest paying $480 as a ransom in 3 days or $980 later. Since the note isn’t very detailed, the criminals suggest contacting them via two provided emails: helpteam@mail.ch or helpmanager@airmail.cc.
The aim of this ransomware is to temporarily lock victim’s files and restrict access to them, hoping to force the victim to do whatever it takes to recover the files. The _readme.txt note specifies that all files, such as documents, photos, videos, databases and other format data were encrypted. The attackers explain that all files have been encrypted with the strongest encryption and unique key, so to decrypt .nusm files, the victim needs to purchase the special decryption tools from the cybercriminals.
The ransom note suggests that the cybercriminals are the only ones who can restore encrypted files back to their original condition. They even suggest “test decryption” service for the victim. The victim can send one encrypted file to the attackers and expect to receive a decrypted version in return. In addition, the criminals provide the decryption software price conditions: if the victim writes to the provided emails within 72 hours (3 full days) from the initial infection timestamp, the criminals offer the decryption software for $490 in Bitcoin. Otherwise, the price jumps to $980.
Bear in mind that cybercriminals cannot be trusted and paying the ransom isn’t recommended by cybercriminals and even FBI. There are more than enough reasons not to pay:
- The criminals might not provide the decryption tool, even if you decide to pay up.
- The tool provided by the criminals might be faulty and might be useless in data decryption;
- Paying the ransom might be considered illegal in your country;
- Listening to cybercriminals’ hefty demands and transferring money to them is exactly what makes this illegal industry attractive for other people, convincing them to join in. The fact that ransomware operators collect millions in ransoms each year simply proves they rake up more than enough by extorting computer users;
- STOP/DJVU variants are known to install variant of AZORULT Trojan on infected systems. Therefore, think twice before you make your decision, because these attackers not only try to extort you, but also install an information and password stealer and do not mention a word about it.
Damage caused by ransomware: what has been done to your computer?
NUSM ransomware begins the attack by bypassing Windows security measures and then starts scanning the entire computer system for target file formats to encrypt. It sure bypasses some folders to ensure that the computer continues to function. The algorithm used to encrypt victim’s files is called RSA Salsa 20, a very secure method and the virus applies it only on the first 150KB of the file. While this can entirely corrupt some file formats, visual files such as images/videos can be repaired in certain conditions.
To prevent the victim from recovering data using Windows in-built tools, it deletes Volume Shadow Copies. Additionally, the ransomware modifies Windows HOSTS file by adding a set of domains that publish various computer-related information and might provide ransomware-related help for the victim. This is done to confuse the victim and possibly make one panic, thinking that there are a lot of problems with the compromised computer.
As stated previously, NUSM virus also drops AZORULT Trojan on the system. This malware is capable of working as a remote access tool and can be used to view, download or delete files from the target system as well as steal various login credentials from applications like Steam and Telegram, also grab browsing history, saved passwords and cookies from them. Finally, this malware is capable of stealing cryptocurrency wallets from the compromised PC.
Needless to say, the list of malicious activities performed by the ransomware and the Trojan is lenghty. Therefore, we recommend you to stop the malicious processes in your computer and remove NUSM ransomware virus without any hesitations and as soon as possible. You can use malware removal software of your choice. We recommend using RESTORO to repair virus damage on Windows OS files afterward.
Scan your system for FREE to detect security, hardware and stability issues. You can use the scan results and try to remove threats manually, or you can choose to get the full version of software to fix detected issues and repair virus damage to Windows OS system files automatically. Includes Avira spyware/malware detection & removal engine.
Ransomware Summary
| Name | NUSM Ransomware Virus |
| Type | Ransomware; Crypto-malware; Virtual Extortion Virus |
| Family | STOP/DJVU |
| Encryption type | RSA Salsa20 |
| Previous versions | VYIA, QBAA, FOPA, VTYM, KQGS, XCBG, BPQD (find full list here) |
| Version | 298th |
| Extension | .nusm |
| Damage | This ransomware leverages RSA Salsa20 algorithm to encrypt all files on the compromised host. Each modified file gets appended with a new extension (file marker). The virus also eliminates system restore points (VSS) and modifies Windows HOSTS file to restrict access to certain Internet pages. |
| Ransom note | _readme.txt |
| Ransom demand | $490-$980 in Bitcoin |
| Distribution | Spreads via illegal torrent downloads, cracked software or KMSPico. |
| Detection names | Trojan:Win32/Glupteba (Microsoft), Glupteba.Backdoor.Bruteforce.DDS (Malwarebytes), TR/AD.InstaBot.bfsbw (Avira), HEUR:Exploit.Win32.Shellcode.gen (Kaspersky), Trojan.GenericKD.36669904 (B)(Emsisoft), W32.Trojan.Gen (Webroot) see all detection name variations on VirusTotal |
| Removal | Use trusted malware removal software to eliminate the ransomware and related malware from your PC. Afterward, scan with RESTORO to repair virus damage on Windows OS files. |
Tricks used for ransomware distribution
Since NUSM ransomware is part of STOP/DJVU virus family, the technique used for its distribution matches all previous variants (such as IGVM‘s or REJG’s). The operators behind this ransomware pack malicious scripts into various illegal downloads, such as software cracks, keygens, KMSPico and others. Once launched, the malicious script connects to an external domain, downloads the ransomware and executes it on the victim’s computer. Often times, the ransomware even displays a fake Windows update prompt. This is done to convince the victim that the update is to be blamed for a sudden system slowdown, while actually the data encryption process is the culprit.
Cybercriminals know that there are many computer users who head to various torrent-sharing websites to get paid software for free. Typically, there are a few kinds of software that interests computer users the most – it’s various games and video or photo editing software. However, attempts to get these paid programs for free almost always lead to silent computer installation. For this reason, we recommend you to avoid shady downloads and only look for desired software on their official developer’s or distributors’ sites.
What is even worse is that computer users who look for illegal software activation means tend to ignore security software’s warnings about a potentially malicious file, thinking that these are simply false positive detections.
Another popular technique used to spread malware is email spam. This is where the attackers get very creative and come up with various topics when targeting potential victims. The one scheme that’s used most frequently is pretending to be a well-known company representative who is sending an important document, such as invoice, payment information or other file that needs to be overviewed by the victim. Unfortunately, opening such email simply starts the malicious script that’s meant to fire the trigger and drop the malicious payload on victim’s PC. The worst part is that these scam emails can be hard to identify nowadays, because the attackers often use email spoofing techniques that allows sender’s email appear legitimate. In other words, the email sender’s email that appears above the message can be different from the one that was actually used to send the email.
All STOP/DJVU ransomware victims should beware of new scam technique circulating around: operators of other ransomware strains, such as ZORAB, are advertising fake STOP/DJVU ransomware decryption tools that actually are ransomware in disguise. In this situation, opening such file will result in double file encryption.
Remove NUSM ransomware virus and decrypt or repair your files
If you’ve fallen victim to the described malware, you should remove NUSM ransomware virus as soon as possible. Luckily, it won’t be hard because we provide a free and easy-to-follow virus removal guide below. We strongly recommend using RESTORO to repair virus damage on your system as well. If you have any questions, do not hesitate and get in touch with our team or leave a question down below in the comments section.
Once NUSM virus removal is completed, we recommend doing the following steps:
- Report Internet crime incident to an authority responsible of handling such cases in your country. You can find some links down below.
- Look for data backups and, if you have them, use them to recover your files;
- Follow the guide to decrypt or repair STOP/DJVU files given down below or in this separate post.
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Our team recommends a two-step rescue plan to remove ransomware and other remaining malware from your computer, plus repair caused virus damage to the system:
STEP 1. REMOVE AUTOMATICALLY WITH ROBUST ANTIVIRUS
STEP 2. REPAIR VIRUS DAMAGE TO YOUR COMPUTER
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NUSM ransomware virus Removal Guidelines
Method 1. Enter Safe Mode with Networking
Step 1. Start Windows in Safe Mode with Networking
Before you try to remove NUSM ransomware virus virus, you must start your computer in Safe Mode with Networking. Below, we provide the easiest ways to boot PC in the said mode, but you can find additional ones in this in-depth tutorial on our website – How to Start Windows in Safe Mode. Also, if you prefer a video version of the tutorial, check our guide How to Start Windows in Safe Mode on Youtube.
Instructions for Windows XP/Vista/7 users
- First of all, turn off your PC. Then press the Power button to start it again and instantly start pressing F8 button on your keyboard repeatedly in 1-second intervals. This launches the Advanced Boot Options menu.
- Use arrow keys on the keyboard to navigate down to Safe Mode with Networking option and press Enter.
Instructions for Windows 8/8.1/10/11 users
- Open Windows Start menu, then press down the Power button. On your keyboard, press down and hold the Shift key, and then select Restart option.
- This will take you to Windows Troubleshoot screen. Choose Troubleshoot > Advanced Options > Startup Settings > Restart. Tip: If you can't find Startup Settings, click See more recovery options.
- In Startup Settings, press the right key between F1-F9 to enter Safe Mode with Networking. In this case, it is the F5 key.
Step 2. Remove files associated with the virus
Now, you can search for and remove NUSM ransomware virus files. It is very hard to identify files and registry keys that belong to the ransomware virus, Besides, malware creators tend to rename and change them repeatedly. Therefore, the easiest way to uninstall such type of a computer virus is to use a reliable security program such as INTEGO Antivirus, which also includes data recovery software. For virus damage repair, consider using RESTORO.
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Method 2. Use System Restore
In order to use System Restore, you must have a system restore point, created either manually or automatically.
Step 1. Boot Windows in Safe Mode with Command Prompt
Instructions for Windows XP/Vista/7 users
- Shut down your PC. Start it again by pressing the Power button and instantly start pressing F8 button on your keyboard repeatedly in 1-second intervals. You will see Advanced Boot Options menu.
- Using arrow keys on the keyboard, navigate down to Safe Mode with Command Prompt option and press Enter.
Instructions for Windows 8/8.1/10/11 users
- Launch Windows Start menu, then click the Power button. On your keyboard, press down and hold the Shift key, and then choose Restart option with the mouse cursor.
- This will take you to Windows Troubleshoot screen. Choose Troubleshoot > Advanced Options > Startup Settings > Restart. Tip: If you can't find Startup Settings, click See more recovery options.
- In Startup Settings, press the right key between F1-F9 to enter Safe Mode with Command Prompt. In this case, press F6 key.
Step 2. Start System Restore process
- Wait until system loads and command prompt shows up.
- Type cd restore and press Enter, then type rstrui.exe and press Enter. Or you can just type %systemroot%system32restorerstrui.exe in command prompt and hit Enter.
- This launches System Restore window. Click Next and then choose a System Restore point created in the past. Choose one that was created before ransomware infection.
- Click Yes to begin the system restoration process.
After restoring the system, we recommend scanning the system with antivirus or anti-malware software. In most cases, there won't be any malware remains, but it never hurts to double-check. In addition, we highly recommend checking ransomware prevention guidelines provided by our experts in order to protect your PC against similar viruses in the future.
Alternative software recommendations
Malwarebytes Anti-Malware
Removing spyware and malware is one step towards cybersecurity. To protect yourself against ever-evolving threats, we strongly recommend purchasing a Premium version of Malwarebytes Anti-Malware, which provides security based on artificial intelligence and machine learning. Includes ransomware protection. See pricing options and protect yourself now.
System Mechanic Ultimate Defense
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Disclaimer. This site includes affiliate links. We may earn a small commission by recommending certain products, at no additional cost for you. We only choose quality software and services to recommend.
Decrypt NUSM files
Fix and open large NUSM files easily:
It is reported that STOP/DJVU ransomware versions encrypt only the beginning 150 KB of each file to ensure that the virus manages to affect all files on the system. In some cases, the malicious program might skip some files at all. That said, we recommend testing this method on several big (>1GB) files first.
- Create a copy of encrypted file to a separate folder using Copy > Paste commands.
- Now, right-click the created copy and choose Rename. Select the NUSM extension and delete it. Press Enter to save changes.
- In the prompt asking whether you want to make the changes as file might become unusable, click OK.
- Try opening the file.
STOP/DJVU decryption tool usage guide
STOP/DJVU ransomware versions are grouped into old and new variants. NUSM ransomware virus is considered the new STOP/DJVU variant, just like VYIA, QBAA, FOPA, VTYM, KQGS, XCBG, BPQD (find full list here). This means full data decryption is now possible only if you have been affected by offline encryption key. To decrypt your files, you will have to download Emsisoft Decryptor for STOP DJVU, a tool created and maintained by a genius security researcher Michael Gillespie.
Note! Please do not spam the security researcher with questions whether he can recover your files encrypted with online key - it is not possible.
In order to test the tool and see if it can decrypt NUSM files, follow the given tutorial.
- Download the decryption tool from Emsisoft.
- Click the little arrow next to your download and choose Show in Folder.
- Now, right-click the file and choose Run as Administrator. If asked, enter administrator's password.
- In UAC window, click Yes.
- Click Yes to agree to software terms in both windows.
- The tool will automatically include C:// disk as a location to decrypt. The file recovery tool will prepopulate the locations to scan, including connected data storage drives or network drives. Click Add folder if you wish to add additional locations.
In Options tab, you can choose to keep encrypted file copies. We recommend leaving this option selected, especially if you do not know if the decryption tool will work. - Click Decrypt to start restoring NUSM files. You will see the progress in the Results tab. Here, you can see messages from the tool, such as whether the decryption procedure is successful, or you need to wait for an update.
You might also be informed that online key was used to encrypt your files. In such case, the decryption tool won't work for you, and the only way to recover your files is to use a data backup.
Meanings of decryptor's messages
The NUSM decryption tool might display several different messages after failed attempt to restore your files. You might receive one of the following messages:
Error: Unable to decrypt file with ID: [example ID]
This message typically means that there is no corresponding decryption key in the decryptor's database.
No key for New Variant online ID: [example ID]
Notice: this ID appears to be an online ID, decryption is impossible
This message informs that your files were encrypted with online key, meaning no one else has the same encryption/decryption key pair, therefore data recovery without paying the criminals is impossible.
Result: No key for new variant offline ID: [example ID]
This ID appears to be an offline ID. Decryption may be possible in the future.
If you were informed that an offline key was used, but files could not be restored, it means that the offline decryption key isn't available yet. However, receiving this message is extremely good news, meaning that it might be possible to restore your NUSM extension files in the future. It can take a few months until the decryption key gets found and uploaded to the decryptor. We recommend you to follow updates regarding the decryptable DJVU versions here. We strongly recommend backing up your encrypted data and waiting.
Report Internet crime to legal departments
Victims of NUSM ransomware virus should report the Internet crime incident to the official government fraud and scam website according to their country:
- In the United States, go to the On Guard Online website.
- In Australia, go to the SCAMwatch website.
- In Germany, go to the Bundesamt für Sicherheit in der Informationstechnik website.
- In Ireland, go to the An Garda Síochána website.
- In New Zealand, go to the Consumer Affairs Scams website.
- In the United Kingdom, go to the Action Fraud website.
- In Canada, go to the Canadian Anti-Fraud Centre.
- In India, go to Indian National Cybercrime Reporting Portal.
- In France, go to the Agence nationale de la sécurité des systèmes d’information.
If you can't find an authority corresponding to your location on this list, we recommend using any search engine to look up "[your country name] report cyber crime". This should lead you to the right authority website. We also recommend staying away from third-party crime report services that are often paid. It costs nothing to report Internet crime to official authorities.
Another recommendation is to contact your country's or region’s federal police or communications authority.
Frequently Asked Questions
You can only open NUSM files if you have the decryption key, or if you were affected by offline encryption type.
To figure out whether you were affected by offline encryption, please go to C:/SystemID/PersonalID.txt and see if the string inside of it ends in t1. You can also try using Emsisoft Decryptor for STOP/DJVU.
Please follow the guidances provided by the official NUSM decryption tools and believe what they say. If they say it is impossible to decrypt, it really is so. There is no magic tool or human capable of decrypting your files hiding somewhere. Encryption is a technique created to be nearly impossible to decrypt without a special private key (held by the criminals).
We advise scanning with anti-virus, anti-malware, malware removal tools or software like RESTORO to eliminate virus damage on the system. If you do not trust using a single tool, try running one after another. However, we do not recommend keeping several security programs on a computer at once as they can interfere with each other's work.
Beware of fake NUSM decryption tools circulating around the web. Cyber criminals are uploading them to various shady websites, also might be promoting them via suspicious Youtube videos. These programs can infect your computer even more heavily (Trojans, miners, etc.). We suggest being extremely cautious around the web. If there will be an official STOP/DJVU decryption tool available, it will be widely discussed in public media.
Norbert Webb is the head of Geek’s Advice team. He is the chief editor of the website who controls the quality of content published. The man also loves reading cybersecurity news, testing new software and sharing his insights on them. Norbert says that following his passion for information technology was one of the best decisions he has ever made. “I don’t feel like working while I’m doing something I love.” However, the geek has other interests, such as snowboarding and traveling.
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can someone please help me
my usb drive has been affected by nusm virus
My pc has been affected by the nusm virus and the software stop Djvu isn't able to decrypt my files. I request you to please help me. I had many precious pictures and videos of my belated sister so I just want that so please help me!