NZTT Virus (.NZTT File) 🔐 Decrypt & Removal Guide

Nztt virus is a ransomware, a part of STOP/Djvu family. This malware is infamous for file encryption and following ransom demands. Once Nztt virus is launched in a system, it ciphers valuable files, typically MS Office document, videos, photos and the like. Encrypted files receive a distinctive “.nztt” extension, and become unusable without the decryption.

Nztt Virus Overview

Nztt

🤔 Nztt virus is ransomware that belongs to the DJVU/STOP family. Its primary purpose is to encrypt files that are important to you. Then, this ransomware asks its victims for a ransom fee – ($490 – $980) in Bitcoin.

The Nztt virus is a type of malware that ciphers your files and coerces you into paying for their recovery. This ransomware ciphers various file types. ciphered files are identifiable by a distinct “.nztt” extension. The affected files become impossible to access and use.

After that, the ransomware asks for a file decryption payment in Bitcoin from its victims, that ranges from $490 to $980, depending on the time passed after the attack. In all cases, a text file with ransom payment guidances is named as “_readme.txt“.

Nztt Ransomware works with Salsa20 encryption algorithms to cipher the files. Since Nztt virus utilizes such a strong encryption method, it becomes particularly difficult, if even possible, to find the decryption key without the assistance of the attackers.

Once Nztt malware finishes the encryption, it shows a ransom note to the user, demanding a ransom payment for the decryption key. The ransom note provides instructions on how to pay off the bill and also often contains threats of system wipeout or increased ransom amounts if the demands are not met within a specified timeframe.

I have compiled an all-encompassing list of potential solutions, advice, and methods to neutralize the Nztt malware and recover your files. There are situations where it may be feasible to restore your files, while sometimes, it may be impossible.

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📌 Important Note!

It is important to note that paying off the bill is not a guarantee of the successful files recovery. The individuals behind the Nztt virus are not trustworthy. There were the cases where people have paid the ransom, only to be denied by the cybercriminals with the decryption key provision.

Nztt employs a unique key for each victim, with one exception:

The Nztt virus bears resemblance to other DJVU ransomware variants such as Wzer, Wzoq, Wzqw, and Wztt. This virus encrypts a wide range of common file types and appends its distinct “.nztt” extension to all files. For instance, a file named “1.jpg” would be altered to “1.jpg.nztt” and “2.png” to “2.png.nztt“.

Upon successful encryption, malware spawns a special text file named “_readme.txt” and places it in every folder containing the encrypted files. It as well adds this file to the desktop, so the victim will not miss the attack even without opening folders.

The image below provides a visual representation of files with the “nztt” extension:

Encrypted Files by STOP/DJVU Ransomware

Name	Nztt Virus
Ransomware family¹	DJVU/STOP² ransomware
Extension	.nztt
Ransomware note	_readme.txt
Ransom	From $490 to $980 (in Bitcoins)
Contact	[email protected], [email protected]
Detection	Win32/Filecoder.Conti.L, Win32:PWSX-gen [Trj], PWS:Win32/Fareit!MTB
Symptoms	Disables Volume Shadow copies, making victim’s attempts to restore data futile; Installs password-stealing Trojan on the system, like Vidar Stealer or RedLine Stealer; Successfully installs a SmokeLoader backdoor for remote access; Updates the HOSTS file with a list of domains to block access to certain security-related sites; Implements encryption to lock most of your files (photos, videos, documents) and adds a particular “.nztt” extension;
Fix Tool	To remove possible malware infections, scan your PC: 6-day free trial available.

This message asking payment is for restore files via decryption key:

_readme.txt (STOP/DJVU Ransomware) – The alarming warning insisting users to pay off the ransom to unlock the encrypted data contains these exasperating cautions.

Nztt ransomware arrives as a set of procedures that are used to carry out different activities on a victim’s computer. One of the first processes being launched is winupdate.exe, a deceptive process that displays a fraudulent Windows update prompt during the attack. That is needed to convince the victim that a sudden PC slowdown is caused by a Windows update.

Meanwhile, the ransomware runs another process (which name commonly consists of 4 random characters) which starts scanning the computer for target files and ciphering them. Next, the ransomware removes Volume Shadow Copies from the disk using the following CMD command:

vssadmin.exe Delete Shadows /All /Quiet

Once erased, it becomes impossible to retrieve the previous computer state using System Restore Points. The issue is, ransomware operators are getting rid of any built-in Windows approaches that could assist the victim to restore files for free. In addition, the rascals modify the Windows HOSTS file by including a list of domains to it and directing them to the localhost IP. As a result, the victim will see a DNS_PROBE_FINISHED_NXDOMAIN error when accessing one of the listed websites.

It has come to our attention that ransomware attempts to restrict websites that developed various how-to guides for computer users. It is clear that by hindering specific domains, the perpetrators are seeking to hinder the victim from reaching relevant and helpful ransomware-attack-related information online. Malware also stores two .txt files on the victim’s computer that provide attack-related particulars – the public key of this victim and personal ID. These two files are named bowsakkdestx.txt and PersonalID.txt.

After all these alterations, the malware doesn’t stop. Variants of STOP/DJVU have a tendency to release Vidar password-stealing Trojan on compromised systems. This threat has an huge list of capabilities, including:

Infiltrating the victim’s computer with malware and executing it to gain unauthorized access.
Obtaining unauthorized access to login credentials of Steam, Telegram, and Skype.
Manipulating and viewing files on the victim’s computer without their knowledge.
Stealing cryptocurrency wallets from the victim’s system.
Granting the hackers remote control over the victim’s computer for various malicious activities.
Extracting sensitive information such as browser cookies, saved passwords, and browsing history.

The encryption algorithm used by DJVU/STOP virus is AES-256. So, once your data is encrypted with an online decryption key, the chances to get your files back are quite low. Thing is, the key is unique for each victim, and brute forcing it will take exceptionally big amount of time.

Getting the online key in another way is also merely impossible. It is kept on a remote server owned by the crooks who spread the Nztt malware. For receiving decrypting code the payment should be $980. To get the payment details, the victims should contact the hackers by email ([email protected]).

The message by the ransomware states the following information:

ATTENTION!

Don't worry, you can return all your files!

All your files like photos, databases, documents and other important are encrypted with strongest encryption and unique key.
The only method of recovering files is to purchase 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 file from your PC and we decrypt it for free.
But we can decrypt only 1 file for free. File must not contain valuable information.

You can get and look video overview decrypt tool:

https://we.tl/t-WJa63R98Ku

Price of private key and decrypt software is $980.
Discount 50% available if you contact us first 72 hours, that's 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 answer more than 6 hours.

To get this software you need write on our e-mail:

[email protected]

Reserve e-mail address to contact us:

[email protected]

Your personal ID:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Do not pay the ransom!

Please, try to use the available backups, or Decrypter tool

_readme.txt file also indicates that the system owners must get in touch with the hackers’ representatives during 72 hours since the file encryption. If user contacts hackers within 72 hours, hackers grant a 50% discount. This decreases the ransom sum down to $490.

Yet, stay away from paying off the ransom! I strongly recommend that you to avoid contacting these swindlers and do not pay. An efficient solution to regain the lost data is just using the available backups, or using Decrypter tool from Emsisoft.

The peculiarity of such malware is the employment a similar set of actions for generating the unique decryption key to recover the ciphered data. Thus, unless the ransomware is still in development or possesses with some hard-to-track flaws, manual data recovery is a thing you can’t perform. The exclusive resolution to prevent the loss of your valuable data is to regularly make backups of your critical files.

Remember that even if you do preserve such backups regularly, they should be stored 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. Alternatively, you may refer to the help of online (cloud) information storage.

Needless to say, when you keep your backup on your common device, it may be similarly ciphered as well as other data. For this reason, placing the backup on your computer’s disk is surely not a wise idea.

How I was infected?

Ransomware has a various methods to built into your system. But it doesn’t really matter what way had place in your case.

Ransomware attack following a successful phishing attempt.

Nevertheless, these are the common leaks through which it may be injected into your PC:

Concealing the virus within seemingly legitimate apps, especially utilities provided as freeware or shareware.
Spreading the virus through spam emails containing suspicious links that lead to the virus installer.
Exploiting online free hosting resources to host and distribute the virus files discreetly.
Obtaining pirated software from illegal peer-to-peer (P2P) resources, which may unknowingly contain malware.

Some incidents occurred when the Nztt virus was disguised as a legit tool, for example, the messages requesting to install a browser update or a vastly needed codec for online media playback. This is commonly the way how some online scams aim to force you into installing the ransomware manually, by actually making you directly participate in this process.

Surely, the fraudulent update alert will not indicate that you are installing the threat. This process will be disguised under some alert stating that you must install an urgent security update or some suspicious program whatsoever.

Certainly, the software cracks represent the damage as well. Using P2P is both illegal and may end up with the injection of serious malware, including the Nztt ransomware.

To sum up, what can you do to evade the injection of the ransomware into your computer? Even though there is no 100% assurance to thwart your PC from getting compromised, there are some tips I want to give you to avert the Nztt penetration. You must be vigilant while setting up free software today.

Ensure you always read what the installer offers aside from the main free program. Stay away from opening suspicious email attachments. Do not open files from the unknown addressees. Certainly, your current anti-malware program must always be updated.

The malware does not show itself openly. It will not be mentioned in the list of your available programs. However, it will be masked under some malevolent process running consistently in the background, that starts at the moment when you boot up your computer.

How To Remove Ransomware?

Video Guide

How To Decrypt .nztt Files?

How to restore big files?

Try deleting .nztt extension on a few big files and opening them. This malware has issues with large files encryption. Either the virus accessed and did not encode the file, or it failed and did not add the filemarker. If your files are very large (2GB+), such a situation is highly probable. Please, text me in the comments whether this helped you or not.

The newest extensions released around the end of August 2019 after the criminals made changes. This includes Wzer, Wzoq, Wzqw etc.

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

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

Select folders for decryption.

Based on the default configurations, the decryptor will by default choose the accessible directories in order to decode the currently available drives (the connected ones), including the network drives. Additional (optional) locations can be selected with the help of the “Add” button.

Decryptors usually offer several options considering the specific malware family. The existing possible options are displayed in the Options tab and can be enabled or turned off there. You may find a comprehensive list of the currently active Options below.

Click on the “Decrypt” button.

As soon as you 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 files:

✓ Error: Unable to decrypt file with ID: [your ID]

There is no corresponding decryption key in the Emsisoft decryptor’s database.

✓ No key for New Variant online ID: [your ID]

Notice: this ID appears to be an online ID, decryption is impossible

Your original files were encrypted with an online key. So no one else has the same encryption/decryption key pair. File recovery is only possible through paying the ransom. 🙁

✓ Result: No key for new variant offline ID: [example ID]

This ID appears be an offline ID. Decryption may be possible in the future.

Malware used an offline key, but files could not be restored (the offline decryption key isn’t available yet). Nonetheless, receiving this message is good news for you, since it might be possible to restore your files in the future. 🙂
It can take a few weeks or months until the decryption key gets found and uploaded to the decryptor. Please follow updates regarding the decryptable DJVU versions here.

✓ Remote name could not be resolved

It’s an indication of a DNS issue on your PC. Try resetting your HOSTS file to default.

How to Restore .nztt Files?

In some case ransomware is not doom for your files…

The Nztt ransomware encryption mechanism sequence is next: it ciphers every file byte-by-byte, then saves a duplicate, deleting (not overriding!) the initial file. Thus, the data of the file location on the physical disk is lost, but the original file is not removed from the physical disk. The cell, or the sector where this file was stored, can still hold this file, but it is absent in the file system and can be overwritten by data that has been loaded to this disk after the deletion. Hence, it is possible to restore your files using special software.

I recently had my pc infected by the this virus. It managed to bypass 2 Antivirus software and 2 malware fighters.

Anyway, after realizing it was an online algorithm, it is impossible to retrieve my encrypted files. I also had my backup drive plugged in at the time of the virus, and this was also infected, or so I thought. Every folder within my backup drive had been infected and was encrypted. However, despite losing some important files, I retrieved almost 80% of my 2TB storage.

When I started going through the folders, I noticed the readme.txt ransom note in every folder. I opened some of the folders and found that all files that were not in a subfolder within that folder had been encrypted. However, I found a flaw and glimmer of hope when I went into the subfolders in other folders and found that these files had not been encrypted. Every folder within my c and d drives, including subfolders, had been encrypted, but this was not the case with the backup drive. Having subfolders created within a folder has saved 80% of my data.

As I said, I believe this to be only a small loophole on a backup drive. I’ve since found a further 10 % of my data on another hard drive on a different pc. So my advice is if you use a backup drive, create subfolders. I was lucky, I guess. But I was also unlucky that the virus hit as I was transferring some files from my backup.

Hopefully, this can help some other people in my situation.

Jamie Newland

Some pointers for recovery repair of Nztt files (true for all STOP/DJVU variants):

I have seen Stop/Djvu variants fail to encrypt deeper nested folders, so that you can check that. You may find those are not encrypted.

This ransomware saves encrypted data to a new file, deletes the original. So there’s a slight chance part of that deleted file can be recovered using file recovery software. It’s unlikely the folder structure can be restored, so a free tool like PhotoRec may be as good as any.

This ransomware only partially encrypts (about the first 150 KB), so depending on file size and type of data, the not encrypted part may be recoverable.

Joep

Recovering your files with PhotoRec

PhotoRec is an open-source program, which is originally created for file retrieval from damaged disks, or for files recovery in case if they are unintentionally deleted. However, as time has gone by, this program received the ability to retrieve the files of 400 different formats. Hence, it can be used for data recovery after the Nztt attack.

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

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

Upon the launch, you will see the screen showing you the complete list of your disk spaces. However, this data is probably futile, because the required menu is placed a bit higher. Click this tab, then choose the disk which was attacked by ransomware.

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

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

Finally, you can begin files retrieval by pressing the “Search” button. You will observe the screen where the findings of the scan and recovery are shown.

Nztt files recovery Video Guide.

Frequently Asked Questions

🤔 How can I open “.nztt” files?

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

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

If your data remained in the .nztt files are very valuable, then most likely you 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 Nztt. 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.

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

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

🤔 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 keys or new decryption programs appear.

🤔 What can I do right now?

The Nztt 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.