The aim of this ransomware is to take user’s data hostage, then demand a ransom for its release. The virus creates a text note called _readme.txt (widely known as a ransom note) for the user with instructions from the ransomware operators.

The ransom note introduces decryption tool pricing

The _readme.txt file contains a short message from the ransomware operators. They explain that data on the computer was encrypted, and in order to restore it, they demand “purchasing” a KCBU file decryption tool from them. They also explain that whoever contacts the attackers within 72 hours starting from the infection timestamp, gets a 50% discount on the decryption tools, which means the price would be $490. Otherwise, the victim has to pay the full amount, which is $980. At the end of the ransom note, two email addresses are provided: support@fishmail.top and datarestorehelp@airmail.cc. The note recommends using them to contact the cybercriminals. In addition, there is a suggestion to test the decryption service on one file. The victim can attach one small encrypted file and send it to ransomware operators to find out whether they can actually restore the data. Even if they can, law enforcement agencies like FBI do not recommend paying the ransom. It only encourages the criminals to continue their activities, plus, they might attempt to target you again in the future. What is not mentioned in the ransom note is the malware that came along the data-encrypting threat. Most of STOP/DJVU ransomware versions are spread together with AZORULT, VIDAR or RedLine Stealers, all being highly malicious Trojans used for theft of sensitive information. In order to prevent further damage, we recommend victims to remove KCBU ransomware as soon as it is possible. Boot your computer in Safe Mode with Networking and run a trustworthy AV solution, like the one we recommend (INTEGO Antivirus). It scores excellent rates in malware detection tests and provides real-time protection 24/7. As an additional step, you may want to download RESTORO, a tool that can repair virus damage caused on Windows OS files.

Ransomware Summary

How ransomware-type malware is distributed?

STOP/DJVU ransomware variants, just like other data-encrypting and similar computer viruses, are mainly delivered in disguise of pirated/cracked software versions, fake software updates or malicious email attachments. Our research shows that KCBU virus mainly spreads via deceptive software crack websites. Award-winning antivirus solution for your PC. Robust security software that provides robust 24/7 real-time protection, Web Shield that stops online threats/malicious downloads, and Prevention engine that wards off Zero-Day threats. Keep your PC safe and protected against ransomware, Trojans, viruses, spyware and other forms of dangerous programs. Cybercriminals typically upload fake downloads to various torrent listings or websites claiming to be providers of various cracked software versions. You can read more about such deceptive sites providing dangerous downloads here. Typically, the promoted file is a password-protected archive that contains a setup.exe file. Unfortunately, upon launching it, the user receives a notification that the installer has stopped working. In the meantime, the malware begins preparations for a severe computer attack. It is never a good idea to look for illegal software copies, even if you’re trying to save money. To avoid cybersecurity risks, ensure you download software from trustworthy and official websites only. The software provider and affiliates often provide various discounts that users can use and save money. Trying to completely bypass software license fees can result in a severe computer infection, which will lead to much higher expenses in regards of lost time and data. Another common method used for malware distribution is email spam. The threat actors usually contact the potential targets and send some email attachments that, once opened, can lead to a computer infection. A typical trick that cybercriminals use is impersonating various companies and their representatives, claiming there is an urgent matter that needs to be taken care of. For example, the malicious email might state there is an invoice for you, or an order on its way, or claim that your subscription for an unknown service has been renewed. The aim is to trigger user’s reaction and force him/her to open the malicious attachment or included link quickly. That being said, you should always check for suspicious signs in the email and verify if it was sent from a reliable source. For example, try to check the sender’s email address, the greeting line, overall design of the email message, and grammar mistakes. If you can spot some suspicious signs, do not open the attachments or URLs included in the message. It can lead to a severe computer infection. Another trick used for malware distribution is deceptive software update installers advertised online. If you ever come across an aggressive pop-up ad that claims you need to update Flash or Java urgently, do not do as instructed – instead, visit the official website of the advertised software and check for updates there. If you interact with such ads without checking their reliability, you may end up installing a bunch of spyware/malware along the alleged “update.”

Remove KCBU ransomware virus and decrypt your files

If the described malware has already infiltrated your computer system, we strongly advise you to remove KCBU ransomware remains as well as other malware that may have infected the system. The guide provided below explains how to initiate the removal safely. If you do not have an AV solution yet, consider using INTEGO Antivirus. You can read more about its effectiveness in a full review on our site. Once the malware is removed, consider scanning your computer with RESTORO to identify damage to Windows OS files and repair it wherever possible. In addition, we recommend that you change all the account passwords that you’ve used on the compromised computer. OUR GEEKS RECOMMEND 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: GeeksAdvice.com editors select recommended products based on their effectiveness. We may earn a commission from affiliate links, at no additional cost to you. Learn more. Get INTEGO ANTIVIRUS for Windows to remove ransomware, Trojans, adware and other spyware and malware variants and protect your PC and network drives 24/7. This VB100-certified security software uses state-of-art technology to provide protection against ransomware, Zero-Day attacks and advanced threats, Intego Web Shield blocks dangerous websites, phishing attacks, malicious downloads and installation of potentially unwanted programs. Use INTEGO Antivirus to remove detected threats from your computer. Read full review here. RESTORO provides a free scan that helps to identify hardware, security and stability issues and presents a comprehensive report which can help you to locate and fix detected issues manually. It is a great PC repair software to use after you remove malware with professional antivirus. The full version of software will fix detected issues and repair virus damage caused to your Windows OS files automatically. RESTORO uses AVIRA scanning engine to detect existing spyware and malware. If any are found, the software will eliminate them. Read full review here.

Method 1. Enter Safe Mode with Networking

Before you try to remove KCBU 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 Instructions for Windows 8/8.1/10/11 users Now, you can search for and remove KCBU 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. For virus damage repair, consider using RESTORO.

Method 2. Use System Restore

In order to use System Restore, you must have a system restore point, created either manually or automatically. Instructions for Windows XP/Vista/7 users Instructions for Windows 8/8.1/10/11 users 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 If you’re looking for an all-in-one system maintenance suite that has 7 core components providing powerful real-time protection, on-demand malware removal, system optimization, data recovery, password manager, online privacy protection and secure driver wiping technology. Therefore, due to its wide-range of capabilities, System Mechanic Ultimate Defense deserves Geek’s Advice approval. Get it now for 50% off. You may also be interested in its full review.

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Decrypt KCBU files

Fix and open large KCBU 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.

STOP/DJVU decryption tool usage guide

STOP/DJVU ransomware versions are grouped into old and new variants. KCBU Ransomware Virus is considered the new STOP/DJVU variant, just like BPTO, ISWR, ISZA, BPSM, ZOUU, MBTF, ZNSM (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 KCBU files, follow the given tutorial.

Meanings of decryptor’s messages

The KCBU 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 KCBU 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.

Victims of KCBU 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.