Kolz is a DJVU family of ransomware-type infections1. This virus encrypts important personal files (video, photos, documents). The encrypted files can be tracked by specific “.kolz” extension. So, you can’t use them at all.
In this tutorial I will try to help you remove Kolz ransomware without any payment. As bonus I will assist you in decoding your encrypted files.
What is “Kolz”?
Kolz can be correctly identify as a ransomware-type infection.
Ransomware is a kind of virus that encrypted your documents and then forces you to pay to restore them. Note that DJVU (aka STOP) ransomware family was first revealed and analyzed by virus analyst Michael Gillespie2.Kolz is basically similar to other the same family: Npph, Ogdo, Ogdo. Kolz encrypted all popular file types. Hence, you cannot use the own documents . Kolz adds its own “.kolz” extension into all files. For instance, the file “video.avi”, will be changed into “video.avi.kolz”. As soon as the encryption is successfully accomplished, Kolz generates a specific text file “_readme.txt” and adds it into all folders that contain the modified files.
Here is a summary for the Kolz :
| Ransomware family3 | DJVU/STOP4 ransomware |
| Extension | .kolz |
| Ransomware note | _readme.txt |
| Ransom | From $490 to $980 (in Bitcoins) |
| Contact | helpmanager@mail.ch, restoremanager@airmail.cc |
| Detection | Trojan:Win32/Emotet.PEZ!MTB, Ransom.NetWalker, Ransom:Win32/Netwalker.GM!MTB |
| Symptoms | Most of your files (photos, videos, documents) have a .kolz extension and you can’t open it |
| Fix Tool | See If Your System Has Been Affected by .kolz file virus |
This text asking payment is for get files back via decryption key:
The scary alert demanding from users to pay the ransom to decrypt the encoded data contains these frustrating warnings
The cryptography algorithm used by Kolz is AES-256. So, if your documents got encrypted with a specific decryption key, which is totally unique and there are no other copies. The sad reality is that it is impossible to restore the information without the unique key available.
In case if Kolz worked in online mode, it is impossible for you to gain access to the AES-256 key. It is stored on a remote server owned by the frauds who distibute the Kolz infection.
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 (helpmanager@mail.ch), or via Telegram.
Do not pay for Kolz!
Please, try to use the available backups, or Decrypter tool
_readme.txt file also indicates that the computer owners must get in touch with the Kolz representatives during 72 hours starting from the moment of files where 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). However, stay away from paying the ransom!
I strongly recommend that you do not contact these frauds and do not pay. The one of the most real working solution to recover the lost data – just using the available backups, or use Decrypter tool.
The peculiarity of all such viruses apply 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 with 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 regularly make backups of your crucial files.
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 PC is surely not a good idea.
How I was infected?
Kolz has a various methods to built into your system. But it doesn’t really matter what way was used in your case.
Kolz ransomware attack following a successful phishing attempt.
- hidden installation along with other apps, especially the utilities that work as freeware or shareware;
- dubious link in spam emails leading to the Kolz installer
- online free hosting resources;
- using illegal peer-to-peer (P2P) resources for downloading pirated software.
There were cases when the Kolz virus was disguised as some legitimate tool, for example, in the messages demanding to initiate some unwanted software or browser updates. This is typically the way how some online frauds aim to force you into installing the Kolz ransomware manually, by actually making you directly participate in this process.
Surely, the bogus update alert will not indicate that you are going to actually inject the Kolz ransomware. This installation will be concealed under some alert mentioning that allegedly you should update Adobe Flash Player or some other dubious program whatsoever.
Of course, the cracked apps represent the damage too. Using P2P is both illegal and may result in the injection of serious malware, including the Kolz ransomware.
To sum up, what can you do to avoid the injection of the Kolz ransomware into your device? Even though there is no 100% guarantee to prevent your PC from getting damaged, there are certain tips I want to give you to prevent the Kolz penetration. You must be cautious while installing free software today.
Make sure you always read what the installers offer in addition to the main free program. Stay away from opening dubious email attachments. Do not open files from the unknown addressees. Of course, your current security program must always be updated.
The malware does not speak openly about itself. It will not be mentioned in the list of your available programs. However, it will be masked under some malicious process running regularly in the background, starting from the moment when you launch your PC.
The message by the Kolz ransomware states the following frustrating 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: helpmanager@mail.ch Reserve e-mail address to contact us: restoremanager@airmail.cc Your personal ID: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The image below gives a clear vision of how the files with “.kolz” extension look like:
Example of encrypted .kolz files
How to remove Kolz virus?
In addition to encode a victim’s files, the Kolz virus has also started to install the Azorult Spyware on computer to steal account credentials, cryptocurrency wallets, desktop files, and more.
Reasons why I would recommend GridinSoft5
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 processes6.
Download Removal Tool.
You can download GridinSoft Anti-Malware by clicking the button below:
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 computer.
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.
Press “Install” button.
Once installed, Anti-Malware will automatically run.
Wait for the Anti-Malware scan to complete.
GridinSoft Anti-Malware will automatically start scanning your PC for Kolz 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.
Click on “Clean Now”.
When the scan has finished, 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.
How to decrypt .kolz files?
Restore solution for big “.kolz files“
Try removing .kolz extension on a few BIG files and opening them. Either the Kolz infection read and did not encrypt the file, or it bugged and did not add the filemarker. If your files are very large (2GB+), the latter is most likely. Please, let me know in comments if that will work for you.
The newest extensions released around the end of August 2019 after the criminals made changes. This includes Kasp, Geno, Boop, 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 in order 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 forum messages if you need to do so.
Frequently Asked Questions
No way. These files are encrypted by Kolz ransomware. The contents of .kolz files are not available until they are decrypted.
If your data remained in the .kolz 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.
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.
Have patience. You are infected with the new version of Kolz ransomware, and decryption keys have not yet been released. Follow the news on our website.
We will keep you posted on when new Kolz keys or new decryption programs appear.
No. Nonetheless, a few forms of files may be opened up due to the Kolz encryption mechanism. It blocks just the first 150 kilobytes of each file, hence, you can try to open huge data that are significantly larger than 150KB (MP3, MP4 files). Such action is feasible only when you are making use of the particular players – WinAmp, for instance. The only indication of file encryption is that the first 5-10 seconds of every file is skipping – this part of the file is ciphered.
Kolz ransomware creators will definitely end their activity if their instrument (i.e. ransomware) will quit being financially successful. The fewer encryption situations are solved due to paying the ransom – the much less motivation ransomware creators will have in the future. Unfortunately, huge corporations who have been struck by ransomware generally have no time to wait on the decryption keys. The loss they will have because of downtime can be much bigger than the ransom. However, for customers who can wait up until the secrets are found there is no need to pay a massive ransom.
Ransomware can cipher only that drive which contained its files before the encryption. Hence, all documents on other logical drives are secure. Nonetheless, we have a lot of reports specifying that ransomware can encrypt the external drives, or perhaps inject its primary.exe files on this drive, so your USB drive or external HDD can come to be a Kolz ransomware carrier.
To avoid ransomware injection via such infected external drives, inspect it every single time you plug it in your machine with an antimalware software application. Gridinsoft Anti-Malware can be used for such reason, thanks to its “USB protection” function.
The Kolz 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 just 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 France: Agence nationale de la sécurité des systèmes d’information;
- In Germany: Bundesamt für Sicherheit in der Informationstechnik;
- In Ireland: An Garda Síochána;
Video Guide
It’s my favorite video tutorial: How to use GridinSoft Anti-Malware and Emsisoft Decryptor for fix ransomware infections.
If the guide doesn’t help you to remove Kolz infection, please download the GridinSoft Anti-Malware that I recommended. Also, you can always ask me in the comments for getting help.
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Brendan SmithHow to Remove KOLZ Ransomware & Recover PC
Name: KOLZ Virus
Description: KOLZ Virus is a DJVU family of ransomware-type infections. This infection encrypts important personal files (video, photos, documents). The encrypted files can be tracked by a specific .kolz extension. So, you can't use them at all.
Operating System: Windows
Application Category: Virus
User Review
( votes)References
- Ransomware-type infection: https://en.wikipedia.org/wiki/Ransomware
- Twitter: https://twitter.com/demonslay335
- My files are encrypted by ransomware, what should I do now?
- About DJVU (STOP) Ransomware.
- GridinSoft Anti-Malware Review from HowToFix site: https://howtofix.guide/gridinsoft-anti-malware/
- More information about GridinSoft products: https://gridinsoft.com/comparison
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Hi there! My name is Florin I am 45 I am from Romania and I have a problem with kolz files. My system it was infected and a lot of my files were encrypted. They have kolz termination. I have them saved on a external Harddisk.I used emsisoft, but it seems that the ID is online one, so it seems that is impossible for the moment to recover my files. I am aking you if there is a future hope about recovering my files. My system is now clean, i have Bittdefende total security, but I want to recover my encrypted files.Thank you!
Bigger file isnt encrypted as you said!! I just deleted the extension and its back to normal!!! I can open it.
Thank you Bro!!!!!!!!!!!!!!!!!!!!!!!