What is Kcbu virus?
Kcbu virus is a ransomware that belongs to the family of ransomware called STOP (Djvu). Ransomware is a form of malware used by cyber criminals to lock and encrypt the victim’s data, important files and then demand a payment to unlock and decrypt the data and files. Kcbu encrypts files, renames them by appending the .kcbu extension, and creates files named “_readme.txt” containing the ransom demand message. For example, a file named “image.jpg” will be renamed to “image.jpg.kcbu”, a “document.docx” file to “document.docx.kcbu”, “invoice.pdf” to “invoice.pdf.kcbu”, and so on.
- What is Kcbu virus?
- Remove Kcbu virus (ransomware)
- Decrypt .kcbu files
- Restore .kcbu files
- Video Guide
Kcbu ransomware is a malware designed to encrypt files located on the victim’s computer, and then extort money to decrypt them. Kcbu virus sneaks into the system without any visible symptoms, which is why users notice that their computer is infected too late, when the files are already encrypted. Typically, ransomware such as Kcbu can infect a computer when installing programs downloaded from torrent web-sites as well as when running hacked games, freeware, Microsoft Windows/Office key generators and other similar software.
Upon execution, the virus creates a directory in the Windows system directory, copies itself to this directory, changes some OS settings, and also collects information about the infected computer. After that, Kcbu virus tries to connect to its command server. If this succeeds, the virus sends data about the infected computer to the server, and from it receives a key (so-called ‘online key’) necessary for file encryption. If the connection to the command server has not been established, then the virus uses a fixed key (so-called ‘offline key’). The main difference between an online key and an offline key is that the online key is in the hands of criminals and cannot be determined. The offline key is fixed and can be determined by security researchers. This gives hope that the ransomware victims will be able to decrypt files without paying ransom.
Kcbu virus renames each encrypted file by adding the extension .kcbu to its name. This means the following, if the file was named ‘document.docx’, then after it is encrypted, it will be called ‘document.docx.kcbu’. Each file on the victim’s computer becomes the target of the Kcbu virus. No matter where the file is located, on the internal drive or network storage, this file will be encrypted. The ransomware only does not encrypt files in the Windows system directories, files with the extension .dll, .lnk, .bat, ini, .sys and files named ‘_readme.txt’. Thus, the following types of files can be encrypted:
.srw, .sie, .zip, .tor, .pkpass, .rofl, .cdr, .asset, .dba, .itdb, .jpeg, .m3u, .txt, .bc7, .odc, .wmo, .cas, .3ds, .x3d, .desc, .xld, .cfr, .menu, .wbz, .vtf, .cr2, .rim, .xyw, .sr2, .lbf, .xmind, .bik, .hkdb, wallet, .wbc, .dmp, .snx, .wmf, .wps, .flv, .ws, .xar, .doc, .upk, .itl, .m4a, .r3d, .vdf, .gdb, .odt, .docm, .pdf, .das, .wsh, .xlsx, .webp, .crt, .ybk, .odm, .zabw, .xbplate, .ff, .kdc, .wma, .wcf, .kdb, .zw, .litemod, .pdd, .fsh, .bkp, .pptm, .mlx, .cer, .xlsm, .vfs0, .re4, .layout, .erf, .sis, .zif, .der, .xml, .t13, .pak, .odp, .xxx, .rgss3a, .wpe, .vpp_pc, .ltx, .wbk, .jpg, .wpa, .kf, .dng, .mcmeta, .eps, .lrf, .wpd, .vpk, .icxs, .lvl, .mdbackup, .xyp, .dbf, .odb, .fpk, .big, .xmmap, .js, .ibank, .yal, .wmv, .png, .wbmp, .0, .wma, .xlk, .orf, .jpe, .wire, .wgz, .mov, .hkx, .ztmp, .t12, .iwi, .zi, .qdf, .accdb, .d3dbsp, .wpb, .w3x, .bkf, .mdb, .svg, .dxg, .itm, .wdb, .csv, .css, .docx, .nrw, .wot, .z, .ntl, .webdoc, .sidd, .wp6, .xls, .mdf, .2bp, .p7c, .dwg, .iwd, .wp7, .xlsb, .ysp, .dcr, .epk, .wmv, .1st, .wpd, .raf, .xll, .srf, .3dm, .mpqge, .xx, .xdb, .ncf, .rwl, .rtf, .wsd, .p12, .m2, .wbm, .x, .dazip, .bsa, .forge, .apk, .pptx, .wpw, .xlsx, .syncdb, .wri, .3fr, .wbd, .avi, .mddata, .rar, .bar, .xlgc, .wpl, .map, .pem, .xf, .wn, .1, .hplg, .mp4, .wps, .fos, .crw, .wsc, .sid, .sidn, .wp5, .rb, .p7b, .wp4, .psk, .ai, .wpt, .7z, .blob, .ppt, .xwp, .sb, .wav, .esm, .wotreplay, .wmd, .slm, .mrwref, .y, .qic, .yml, .raw, .x3f, .xlsm, .xy3, .wp, .wm, .bay, .wpg, .sql, .sav, .ods, .zdc, .pef
So, every “Kcbu file” is an encrypted file. To decrypt it, you must use the key and the decryptor. This is reported by the authors of Kcbu virus, in a message that they leave on the infected computer. This message is in a file called ‘_readme.txt’. The criminals place such a file in every directory where there is at least one encrypted file. An example of the contents of this file is given below.
The contents of this file are a ransom demand message. Criminals report that all files on the computer are encrypted, and only the key and decryptor can decrypt these files and restore access to their contents. Attackers demand a ransom of $980 in exchange for a key and a decryptor. If the victim is ready to pay the ransom quickly, within 72 hours, the size of the ransom is halved to $490. The authors of the virus offer to decrypt one Kcbu file for free and thus prove the possibility that the files can be decrypted.
Text presented in the Kcbu ransom note:
Don’t worry, you can return all your files!
All your files like pictures, 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:
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:
Reserve e-mail address to contact us:
Your personal ID:
Security researchers confirm that files with .kcbu extension are encrypted and to decrypt them you need to use a key and special software – decryptor. Fortunately there is a Kcbu File Decypt Tool which was created by Emsisoft and named Stop (djvu) decryptor. This tool allows everyone to decrypt encrypted files completely free. Unfortunately, this decryptor is limited in that it can only decrypt files encrypted with an offline key, files encrypted with an online key cannot yet be decrypted. The reason for this is that only the Kcbu creators have the online key and this key cannot be determined or cracked. In addition to using the Kcbu File Decypt Tool from Emsisoft, there are several other ways to restore the content of encrypted files. The instructions below detail how to remove Kcbu ransomware virus, decrypt .kcbu files, and also how to recover encrypted files if the free Kcbu File Decypt Tool could not decrypt them. Read the entire manual carefully. To make it easier for you to follow the instructions, we recommend that you print it or open it on your smartphone.
|Name||Kcbu ransomware, Kcbu file virus|
|Type||Ransomware, Crypto malware, Filecoder, File locker, Crypto virus|
|Ransom amount||$490 or $980 in Bitcoins|
|Detection Names||Win32:PWSX-gen [Trj], W32/GenKryptik.FBYO, Trojan:Win32/Sabsik.FL.B!ml, Trojan.Win32.Save.a, BScope.TrojanDownloader.Deyma, ML/PE-A, BehavesLike.Win32.Lockbit.bc|
|Symptoms||Unable to open documents, photos and music. You get an error message like ‘Windows can’t open this file’, ‘How do you want to open this file’. Files called such as ”, ‘#_README_#’, ‘_DECRYPT_’ or ‘recover’ in each folder with at least one encrypted file.. ‘All files on your computer have been encrypted’ message on your desktop.|
|Distribution methods||Malicious spam (also known as ‘malspam’). Drive-by downloading (when a user unknowingly visits an infected web-page and then malicious software is installed without the user’s knowledge). Social media, such as web-based instant messaging programs. Suspicious webpages.|
|Removal||Kcbu ransomware removal guide|
|Decryption||Kcbu File Decrypt Tool|
How to remove Kcbu virus (ransomware)
Before you start decrypting or recovering .kcbu files, you need to remove Kcbu ransomware and its autostart entries. This must be done since otherwise the ransomware may re-encrypt the restored files. You can stop the ransomware from working, as it is not difficult to do. Another option is to perform a full system scan using free malware removal tools capable of detecting and removing ransomware infection.
It is very important to scan the computer for malware, as security researchers found that spyware could be installed on the infected computer along with the Kcbu ransomware. Spyware is a very dangerous security threat as it is designed to steal the user’s personal information such as passwords, logins, contact details, etc. If you have any difficulty removing the Kcbu virus, then let us know in the comments, we will try to help you.
To remove Kcbu ransomware, follow the steps below:
Kill Kcbu virus
Press CTRL, ALT, DEL keys together.
Click Task Manager. Select the “Processes” tab, look for something suspicious that is the Kcbu ransomware then right-click it and select “End Task” or “End Process” option. If your Task Manager does not open or the Windows reports “Task manager has been disabled by your administrator”, then follow the guide: How to Fix Task manager has been disabled by your administrator.
It is not difficult to detect a process related to the Kcbu ransomware. When looking for a malicious process, pay attention to the process icon and its name. Most often, this ransomware has a process name in the following format: 4-characters.tmp.exe or 4-characters.exe. For example: 7533.tmp.exe, A4b1.exe, CD15.tmp.exe, 19b2.exe. The process name can also contain “(32 bit)”. If you do not find a process with a similar name in the list of processes, then most likely the Kcbu ransomware has finished working. But keep in mind, if you do not remove the ransomware autostart entries, as demonstrated below, and do not delete its file, then after a while it may start again, and if it finds unencrypted files, immediately encrypt them.
Disable Kcbu Start-up
Select the “Start-Up” tab, look for something similar to the one shown in the example below, right click to it and select Disable.
Close Task Manager.
Delete Kcbu Task
Type “Task Scheduler” in the search bar. Click Task Scheduler app in the search results. Click “Task Scheduler Library” in the left panel. On the right panel, right-click to “Time Trigger Task” and select Delete.
Close Task Scheduler.
Remove Kcbu virus
Run Task Manager and select the “Start-Up” tab. Right click to the Kcbu entry and select Open File Location as shown below.
A directory containing one file will open in front of you, this file is the Kcbu virus. It needs to be removed. If you try to delete it immediately, then you will not succeed, since this file is protected from deletion.
To delete this file, you need to do the following. Right-click on the file, select Properties. In the window that opens, select Security tab. Next, click the Advanced button below. A window will open as shown in the following example.
Click Disable inheritance. In the Block inheritance dialog box that opens, select the first item (Convert inherited permissions…) as shown below.
In the Permission entries list, select “Deny Everyone”, click Remove button and then OK. Close the file properties window. You should now be able to remove the Kcbu virus. Right-click on the file and select Delete.
Scan computer for malware
We recommend using MalwareBytes which will completely remove the ransomware from your computer. This tool is an advanced malicious software removal program created by (c) Malwarebytes lab. It uses the world’s most popular anti malware technology. MalwareBytes Antimalware is able to help you remove ransomware, PUPs, trojans, worms, adware, toolbars, and other security threats from your computer for free.
MalwareBytes Anti-Malware can be downloaded from the following link. Save it on your Desktop.
Category: Security tools
Update: April 15, 2020
When the download is complete, close all software and windows on your personal computer. Open a directory in which you saved it. Double-click on the icon that’s named MBSetup such as the one below.
When the install begins, you will see the Setup wizard that will help you install Malwarebytes on your computer.
Once installation is done, you will see window such as the one below.
Now press the “Scan” button to perform a system scan with this tool for the Kcbu ransomware and other security threats. This procedure can take quite a while, so please be patient. While the MalwareBytes program is scanning, you can see number of objects it has identified as threat.
When the scan get completed, it will display the Scan Results. When you’re ready, press “Quarantine” button.
Malwarebytes will now move the selected security threats to the Quarantine. After the process is complete, you may be prompted to restart your computer.
In order to be 100% sure that the computer no longer has the Kcbu crypto malware, we recommend using the Kaspersky virus removal tool (KVRT). This utility, as its name suggests, is created by the Kaspersky lab and uses the core of the Kaspersky Antivirus. Unlike the Kaspersky Antivirus, KVRT has a smaller size and, most importantly, it can work together with an already installed antivirus. This utility has great capabilities and therefore we suggest using KVRT in the last turn to be sure that the Kcbu crypto malware has been removed.
Download Kaspersky virus removal tool on your Windows Desktop by clicking on the link below.
Author: Kaspersky® lab
Category: Security tools
Update: March 5, 2018
Once the downloading process is done, double-click on the Kaspersky virus removal tool icon. Once initialization process is finished, you’ll see the Kaspersky virus removal tool screen as displayed on the screen below.
Click Change Parameters and set a check near all your drives. Click OK to close the Parameters window. Next press Start scan button for checking your machine for the Kcbu ransomware virus . A system scan can take anywhere from 5 to 30 minutes, depending on your computer. While the KVRT tool is scanning, you may see how many objects it has identified as being affected by malicious software.
As the scanning ends, it will show the Scan Results like below.
Next, you need to click on Continue to begin a cleaning process.
How to decrypt .kcbu files
All files with .kcbu extension are encrypted and the only way to access their contents is to decrypt them. To decrypt .kcbu files, you need to use a unique key and the Kcbu File Decypt Tool. As we said above, Emsisoft company was able to create a decryptor and found a way in some cases to determine the key that was used to encrypt the files. This allows victims of the virus to decrypt .kcbu files for free.
To decrypt .kcbu files, use free Kcbu File Decypt Tool
- Download Kcbu File Decypt Tool from the following link.
STOP Djvu decryptor
- Scroll down to ‘New Djvu ransomware’ section.
- Click the download link and save the decrypt_STOPDjvu.exe file to your desktop.
- Run decrypt_STOPDjvu.exe, read the license terms and instructions.
- On the ‘Decryptor’ tab, using the ‘Add a folder’ button, add the directory or disk where the encrypted files are located.
- Click the ‘Decrypt’ button.
Kcbu File Decypt Tool is a free software that can decrypt files that were encrypted with an offline key, as Emsisoft found a way to determine this key. Unfortunately, files encrypted with an online key cannot yet be decrypted. The online key is unique to each infected computer, and at the moment there is no way to find this key. Of course, criminals have this key, but we do not think that paying a ransom is a way to decrypt .kcbu files. In the case when the files are encrypted with an online key, there is a chance to restore the encrypted files using alternative methods, which are described below.
How to find out which key was used to encrypt files
Below we show two ways to help you determine what type of key was used to encrypt the files. This is very important, since the type of key determines whether it is possible to decrypt .kcbu files for free. We recommend using the second method, as it is more accurate.
Find out the type of key using ‘_readme.txt’ file
- Open the ransom demand message (‘_readme.txt’ file).
- Scroll down to the end of the file.
- There you will see a line with the text ‘Your personal ID’.
- Below is a line of characters that starts with ‘0608’ – this is your personal id.
Find out the type of key using ‘PersonalID.txt’ file
- Open disk C.
- Open directory ‘SystemID’.
- Open file named ‘PersonalID.txt’. This file lists ‘Personal ID’s that match the keys that the virus used to encrypt files.
The ‘Personal ID’ is not a key, it is an identifier related to a key that was used to encrypt files. If the ID ends with ‘t1’, then the files are encrypted with an offline key. If the ID does not end with ‘t1’, Kcbu ransomware virus used an online key. If you could not figure out how to determine which key was used to encrypt files, then we can help. Just write a request here or in the comments below.
Kcbu File Decrypt Tool : “No key for New Variant online ID”
If, when you try to decrypt .kcbu files, Kcbu File Decrypt Tool reports:
No key for New Variant online ID: *
Notice: this ID appears to be an online ID, decryption is impossible
It means that your files are encrypted with an ‘online key’ and their decryption is impossible, since only the kook authors have the key necessary for decryption. In this case, you need to use alternative methods listed below to restore the contents of encrypted files.
Kcbu File Decrypt Tool : “No key for New Variant offline ID”
If, during decryption of .kcbu files, Kcbu File Decrypt Tool reports:
No key for New Variant offline ID: *t1
Notice: this ID appears be an offline ID, decryption MAY be possible in the future.
It means the following: your files are encrypted with an ‘offline key’, but the key itself has not yet been obtained by security researchers, in this case, you need to be patient and wait a while, in addition, you can also use alternative ways for recovering encrypted data.
If for some reason you were unable to decrypt the encrypted files, then We recommend to follow the news on our Facebook or YouTube channels. So you ‘ll know right away that it ‘s possible to decrypt .kcbu files.
This video step-by-step guide will demonstrate How to use STOP Djvu decryptor to Decrypt encrypted files.
How to restore .kcbu files
If your files are encrypted with .kcbu extension, then there is a chance that you can recover the files without decryption. We recommend using PhotoRec and ShadowExplorer that are designed to find and recover lost and deleted data. Mostly such programs are paid, but these tools can restore your files for free. Each of these tools has helped many times to recover files after ransomware infection in what would seem to be the most hopeless cases. We want to remind you that before you try to recover files, you need to check your computer for ransomware using free malware removal tools. It is very important to find the Kcbu virus and completely remove it.
Use ShadowExplorer to recover .kcbu files
Modern versions of the Windows OS have one very useful feature. The Windows automatically makes copies of the files you use. These copies are called ‘Shadow Volume Copies’ and are not directly visible to the user. ShadowExplorer will allow you to get easy access to these files, and thus restore the original state of encrypted files. Of course, not everything is so simple, unfortunately very often ransomware deletes these copies, thus preventing the simple recovery of encrypted files. But in some cases, copies of the files remain and allow for quick file recovery. Therefore, our opinion, you need to try this method.
Visit the page linked below to download the latest version of ShadowExplorer for MS Windows. Save it to your Desktop so that you can access the file easily.
Category: Security tools
Update: September 15, 2019
After the downloading process is complete, open a directory in which you saved it. Right click to ShadowExplorer-0.9-portable and select Extract all. Follow the prompts. Next please open the ShadowExplorerPortable folder like below.
Run the ShadowExplorer utility and then choose the disk (1) and the date (2) that you wish to restore the shadow copy of file(s) encrypted by the Kcbu crypto virus as displayed on the screen below.
Now navigate to the file or folder that you wish to recover. When ready right-click on it and press ‘Export’ button as shown in the following example.
This video step-by-step guide will demonstrate How to recover encrypted files using Shadow Explorer.
Use PhotoRec to restore .kcbu files
There is another very good way to recover .kcbu files – use a tool that finds and restores deleted files. We recommend using PhotoRec. This is one of the few programs that allows you to do this for free. The reason that allows you to recover encrypted files using this method is simple – when you or any program, including the ransomware, deletes the file, this file is not deleted, the Windows OS marks it as deleted and hides it. PhotoRec finds such deleted files and restores them. Thus, at the output, you get files in an unencrypted state. The only thing I want to draw your attention to is that the less you used your computer after ransomware infection, the higher your chance of recovering encrypted files.
Download PhotoRec on your Windows Desktop from the link below.
Category: Security tools
Update: March 1, 2018
After the downloading process is done, open a directory in which you saved it. Right click to testdisk-7.0.win and select Extract all. Follow the prompts. Next please open the testdisk-7.0 folder like below.
Double click on qphotorec_win to run PhotoRec for MS Windows. It’ll show a screen similar to the one below.
Choose a drive to recover as displayed below.
You will see a list of available partitions. Select a partition that holds encrypted personal files as shown below.
Click File Formats button and specify file types to restore. You can to enable or disable the recovery of certain file types. When this is complete, click OK button.
Next, click Browse button to select where restored photos, documents and music should be written, then click Search. We strongly recommend that you save the recovered files to an external drive.
Count of restored files is updated in real time. All restored documents, photos and music are written in a folder that you have selected on the previous step. You can to access the files even if the recovery process is not finished.
When the restore is done, press on Quit button. Next, open the directory where recovered photos, documents and music are stored. You will see a contents as displayed on the screen below.
All restored photos, documents and music are written in recup_dir.1, recup_dir.2 … sub-directories. If you are searching for a specific file, then you can to sort your restored files by extension and/or date/time.
This video step-by-step guide will demonstrate How to recover encrypted files using PhotoRec.
How to protect your computer from Kcbu ransomware
Most antivirus software already have built-in protection system against the ransomware. Therefore, if your PC does not have an antivirus program, make sure you install it. As an extra protection, use the HitmanPro.Alert. All-in-all, HitmanPro.Alert is a fantastic utility to protect your PC from any ransomware. If ransomware is detected, then HitmanPro.Alert automatically neutralizes malware and restores the encrypted files. HitmanPro.Alert is compatible with all versions of Microsoft Windows operating system from Windows XP to Windows 10.
First, please go to the link below, then click the ‘Download’ button in order to download the latest version of HitmanPro Alert.
Category: Security tools
Update: March 6, 2019
When downloading is done, open the directory in which you saved it. You will see an icon like below.
Double click the HitmanPro Alert desktop icon. Once the tool is opened, you’ll be shown a window where you can choose a level of protection, like the one below.
Now press the Install button to activate the protection.
To sum up
This guide was created to help all victims of Kcbu ransomware virus. We tried to give answers to the following questions: how to remove Kcbu ransomware; how to decrypt .kcbu files; how to recover encrypted files; what is an online key and what is an offline key. We hope that the information presented in this manual has helped you.
If you have questions, then write to us, leaving a comment below. If you need more help with Kcbu related issues, go to here.