TCBU ransomware seeks to lock you out of access to your files
Contents
TCBU ransomware is a malicious computer virus targeting Windows OS-running systems. It is designed to bypass security measures installed on the computer and encrypt all files stored on it. Since it is a recognized version of STOP/DJVU ransomware, it appends a 4-character .tcbu file extension to every locked file to make it more distinguishable. To illustrate how files are renamed, see the following examples: 1.jpg becomes 1.jpg.tcbu, 2.docx becomes 2.docx.tcbu and so on. In addition, the ransomware creates and saves clones of _readme.txt ransom note file in each data folder.
The aim of this virus is to maliciously use encryption technologies to make files inaccessible for the victim and then demand money in exchange for data decryption tools. In other words, this threat takes victim’s files hostage and then demands ransom. Computer users are advised to never pay ransoms for cybercriminals and keep backups of their files in case they get damaged by malware.
Ransom note provides instructions from threat actors
The people behind TCBU extension virus ensure that the victim notices the ransom note they drop in each data folder. This note, dubbed _readme.txt, contains a message that informs the computer user of what has been done to files stored on the computer. It also reassures the user that all data can still be salvaged, however, only in case the user pays a ransom.
The note provides two email addresses that belong to cybercriminals: support@fishmail.top and datarestorehelp@airmail.cc. According to the note, the victim has to contact the criminals via email and attach one small encrypted file for a service that criminals identify as “test decryption.” They promise to send a decrypted file version back, only to prove that the attackers can actually restore all files.
The ransom note also explains that in order to get a discount on the initial ransom amount, which is $980, the user has to write an email to criminals within 72 hours. The way the crooks put it, this would set the TCBU decryption tool price to $490. In their email reply, the crooks will further explain that the payment can be made using cryptocurrency only, for anonymity purposes.
Cybersecurity experts and law enforcement agencies like FBI recommend ransomware victims to refrain themselves from paying the ransom to cybercriminals. Doing so doesn’t guarantee data recovery, plus, it motivates the attackers and helps them to fuel the malicious operations.
Additional damage inflicted by malware
It is important to understand that STOP/DJVU ransomware variants like TCBU virus rarely arrive as a sole malware to the computer. Typically, installers used to infect user’s computer with malware contain several pieces of malicious software, and so it happens to be the case with this ransomware strain. Experts have discovered that the file-encrypting threat often arrives together with Vidar Stealer, AZORult, or RedLine Stealer. All of these are known to be highly hazardous information-stealing Trojans.
It is important to remove TCBU ransomware virus before it succeeds to do more damage to your computer. Removing it on time can event prevent it from encrypting part of your files. That being said, we strongly recommend you to follow instructions provided below and get rid of the malware launched on your computer. Our team recommends using INTEGO Antivirus for virus removal, and download RESTORO for repairing virus-damaged Windows OS files.
Ransomware Summary
| Name | TCBU Ransomware Virus |
| Type | Ransomware; Crypto-malware; Virtual Extortion Virus |
| Family | STOP/DJVU |
| Encryption type | RSA 2048 + Salsa20 |
| Previous versions | DARJ DAZX, TYWD, TYCX, TYOS, TYPO, JYWD (find full list here) |
| Version | 606th |
| Extension | .tcbu |
| Cybercriminal emails | support@fishmail.top and datarestorehelp@airmail.cc |
| Additional malware dropped | Azorult or Vidar Trojan |
| Damage | The ransomware uses encryption to maliciously modify all files on the PC and marks their original names with .tcbu extension. Ransom notes called as _readme.txt will be dropped in every computer folder. This piece of malware usually drags VIDAR Stealer alongside it and also eliminates VSS from the system. On top of that, it tends to modify Windows HOSTS file to restrict computer user’s access to cybersecurity-related websites online. |
| Ransom note | _readme.txt |
| Ransom demand | $490-$980 in Bitcoin |
| Distribution | Victims often download this ransomware along illegal torrent downloads, cracked software, activators, key generators or tools like KMSPico. |
| Known software cracks to contain this malware | Corel Draw, Tenorshare 4ukey, Adobe Photoshop, Cubase, Adobe Illustrator, Internet Download Manager, Tally, League of Legends. |
| Detection names | Trojan:Win32/Azorult.FW!MTB (Microsoft), Gen:Heur.Mint.Zard.52 (B) (Emsisoft), HEUR:Trojan.Win32.Scarsi.gen (Kaspersky), Gen:Heur.Mint.Zard.52 (BitDefender), Trojan.MalPack.GS (Malwarebytes), ML.Attribute.HighConfidence (Symantec) see all detection name variations on VirusTotal |
| Removal | Remove ransomware and related malware from your PC using trustworthy software like INTEGO Antivirus. To repair virus damage on Windows OS files, download and try RESTORO (secure download link). |
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Tips to avoid ransomware infection
In order to prevent ransomware-type viruses like TCBU from infecting your computer, we strongly recommend that you install a robust security software on your computer first. It will keep you protected in real-time and block unsolicited attempts to drop malware on your PC.
The second most important thing to do when trying to avoid ransomware infections is to recognize sources that similar malware usually come from. They can be sent to you via email in a form of a deceptive attachment (such as Word or PDF file), be uploaded to torrent listing or simply a rogue warez site in a form of a cracked software installation setup, or be pushed alongside fake update installers online.
Speaking of email spam, computer users should be extremely cautious and avoid opening email attachments, as well as inserted links, from messages that come unexpectedly and claim you have an urgent matter to resolve. Such emails typically try to rush the user to click on the email attachment or inserted link without realising the danger behind it. For this reason, you should always double-check the sender’s email address, whole message for its structure, grammar mistakes, logos, and really think whether the email looks like it was sent by a trustworthy entity or simply its impostor.
Additionally, computer users should refrain from visiting rogue websites advertising software cracks, pirated program and game versions and other content that infringes copyrights of the respective owners. Many computer users still think the Internet is endless and can provide free versions of software in high demand, while it is not true. The criminals try to use popular software names for clickbait and convince the user to launch a setup file that is nothing else but malware launcher.
Finally, we advise users to avoid interacting with aggressive online ads pushing various software updates. These ads can lead to installation of deceptive installers containing a bundle of spyware or even malware, therefore, you should remember that the safest place to download software from is the official developer’s website.
Remove TCBU ransomware virus entirely and restore your files
The safest and easiest way to remove TCBU ransomware virus and other threats that were potentially dropped during the breach of computer security is explained below. Our team of experts have provided a list of steps that one should take in order to complete TCBU virus removal. We also recommend using INTEGO Antivirus, and we find it to be one of the best AV solutions available nowadays.
To finalize the malware removal, consider the idea of downloading RESTORO and using it to repair virus-damaged Windows OS files. Afterward, you can use data backups to restore the majority of encrypted files. In addition, do not forget to change all of your passwords because information-stealing Trojans we discussed earlier could have stolen sensitive login credentials and other data.
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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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TCBU 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 TCBU 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 TCBU 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.
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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
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Decrypt TCBU files
Fix and open large TCBU 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 TCBU 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. TCBU Ransomware Virus is considered the new STOP/DJVU variant, just like DARJ DAZX, TYWD, TYCX, TYOS, TYPO, JYWD (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 TCBU 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 TCBU 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 TCBU 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 TCBU 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 TCBU 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 TCBU 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 TCBU 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 TCBU 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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