BHUI Virus 👾 (.BHUI File Ransomware)

While analyzing malware samples submitted to VirusTotal¹, I have identified the presence of Bhui ransomware, which belongs to the STOP/Djvu ransomware family. Once a computer becomes infected, Bhui proceeds to encrypt files and adds the “.bhui” extension to their original filenames. For instance, a file named “a.jpg” would be renamed as “a.jpg.bhui“, while “b.doc” would be transformed into “b.doc.bhui“.

Additionally, apart from encrypting files, Bhui generates a ransom note in the form of a text file named “_readme.txt“. Furthermore, the distribution of Bhui may involve the utilization of information stealers such as Vidar and RedLine.

The ransom note places significant emphasis on the fact that file decryption is solely achievable through the utilization of dedicated decryption software and an exclusive key. To initiate the data decryption process, victims are explicitly instructed to establish contact with the attackers via the provided email addresses ([email protected] or [email protected]).

Moreover, the ransom note presents two distinct amounts, namely $980 and $490, indicating that victims have the opportunity to acquire the decryption tools at a discounted price if they initiate communication with the attackers within a 72-hour window.

The Bhui key is unique for every victim, with one limitation:

If Bhui is not able to establish a connection to its command and control server (C&C Server) prior to beginning its encryption procedure, then it will use the offline key. The key used is the same across all users, which makes it feasible to decrypt files encrypted in a ransomware attack.

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What is Bhui Virus File?

☝️ Bhui ransomware can be identify as a STOP/DJVU malware family.

The Bhui virus is basically similar to other representatives of the same DJVU family: TGVV, Ahtw, Ahui. The image below gives a clear vision of how the files with “.bhui” extension look like:

Bhui File (STOP/DJVU Ransomware)

Name	Bhui Virus
Ransomware family²	DJVU/STOP³ ransomware
Extension	.bhui
Ransomware note	_readme.txt
Ransom	From $490 to $980 (in Bitcoins)
Contact	[email protected], [email protected]
Detection	Ransom:Win32/StopCrypt.PBM!MTB, Ransom:Win32/StopCrypt.PA!MTB
Symptoms	Encrypted most of your files (photos, videos, documents) and adds a particular “.bhui” extension; Can delete Volume Shadow copies to make victim’s attempts to restore data impossible; Adds a list of domains to HOSTS file to block access to certain security-related sites; Installs password-stealing Trojan on the system, like Vidar Stealer or RedLine Stealer; Manages to install a SmokeLoader backdoor;
Fix Tool	To remove possible malware infections, scan your PC: 6-day free trial available.

This _readme.txt file asking payment is for restore files via decryption key:

_readme.txt (STOP/DJVU Ransomware) – The scary alert demanding from users to pay the ransom to decrypt the encoded data contains these frustrating warnings

Bhui ransomware arrives as a set of processes that are meant to perform different tasks on a victim’s computer. One of the first ones being launched is winupdate.exe, a tricky process that displays a fake Windows update prompt during the attack. This is meant to convince the victim that a sudden system slowdown is caused by a Windows update. However, at the same time, the ransomware runs another process (usually named by four random characters) which starts scanning the system for target files and encrypting them. Next, the ransomware deletes Volume Shadow Copies from the system using the following CMD command:

vssadmin.exe Delete Shadows /All /Quiet

Once deleted, it becomes impossible to restore the previous computer state using System Restore Points. The thing is, ransomware operators are getting rid of any Windows OS-based methods that could help the victim to restore files for free. In addition, the crooks modify the Windows HOSTS file by adding a list of domains to it and mapping them to the localhost IP. As a result, the victim will run into a DNS_PROBE_FINISHED_NXDOMAIN error when accessing one of the blocked websites.

We noticed that ransomware attempts to block websites that publish various how-to guides for computer users. It is evident that by restricting specific domains, the crooks are trying to prevent the victim from reaching relevant and helpful ransomware-attack-related information online. The virus also saves two text files on the victim’s computer that provide attack-related details – the victim’s public encryption key and personal ID. These two files are called bowsakkdestx.txt and PersonalID.txt.

After all these modifications, the malware doesn’t stop. Variants of STOP/DJVU tend to drop Vidar password-stealing Trojan on compromised systems. This threat has a lengthy list of capabilities, such as:

Stealing Steam, Telegram, Skype login/password;
Stealing cryptocurrency wallets;
Downloading malware to the computer and running it;
Stealing browser cookies, saved passwords, browsing history, and more;
Viewing and manipulating files on victim’s computer;
Allowing the hackers to perform other tasks on the victim’s computer remotely.

The cryptography algorithm used by DJVU/STOP ransomware is AES-256. So, if your documents got encrypted with an online decryption key, which is totally unique. The sad reality is that it is impossible to decrypt the files without the unique key.

In case if Bhui 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 criminals who promote the Bhui virus.

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 ([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 for Bhui!

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

I strongly advise against contacting these fraudulent individuals and making any payments. One of the most reliable and effective solutions for recovering lost data is to utilize available backups or employ a Decrypter tool.

The peculiarity of all such ransomware viruses is that they follow a similar set of actions to generate a unique decryption key for recovering the encrypted data. Unless the ransomware is still in the developmental stage or possesses hard-to-track flaws, manually recovering the encrypted data is practically impossible. Regularly creating backups of crucial files is the only viable solution to prevent the loss of valuable data.

It is important to note that even if you maintain regular backups, they should be stored in a specific location that is separate from your main workstation. This means they should not be connected to your main computer. For example, you can keep your backups on a USB flash drive or an alternative external hard drive storage. Another option is to utilize online (cloud) information storage services.

It is crucial to understand that if you store your backup data on your main PC, it can also be subject to encryption, just like your other data. Therefore, it is not advisable to keep your backups on your main computer to ensure their safety and accessibility.

How I was infected?

Ransomware has a various methods to built into your PC.

Ransomware employs several methods to infect computers and compromise their files. Understanding these tactics can help you better protect your system against such threats.

One common avenue for ransomware infection is through websites that distribute pirated software or falsely promise downloads of popular YouTube videos. Unscrupulous individuals take advantage of users seeking free access to software or entertainment, embedding malicious code within the files or providing deceptive download links.

Another prevalent method is through emails containing malicious links or attachments. Cybercriminals craft convincing emails that appear legitimate, luring unsuspecting users into clicking on a link or opening an attachment. Once activated, the ransomware quickly infiltrates the system, initiating the encryption process.

Ransomware can also propagate through peer-to-peer (P2P) networks, where users share files directly with one another. These networks provide an environment where malware can easily disguise itself as a legitimate file, tricking users into downloading and executing it, thereby initiating the ransomware attack.

Free file hosting platforms and third-party downloaders pose additional risks. Cybercriminals exploit these platforms by uploading infected files or modifying legitimate files to include malicious code. Users who download files from these sources unknowingly introduce ransomware into their systems.

Trojans, a type of malware that disguises itself as a legitimate program, can also serve as a delivery mechanism for ransomware. These Trojans may be disguised as harmless files or bundled with legitimate software, deceiving users into installing them. Once the Trojan is activated, it unleashes the ransomware payload.

Upon successful infiltration, ransomware employs a variety of file types to carry out its malicious actions. PDF documents, Microsoft Office files, JavaScript files, executable files with the .exe extension, and archive files like ZIP and RAR are commonly used to deliver the ransomware payload. This diversity allows the threat actors to exploit different avenues of attack, increasing the chances of successful infection.

It is essential to remain vigilant and exercise caution while browsing the internet, opening emails, and downloading files. Regularly updating your security software, backing up your files, and practicing safe computing habits can significantly reduce the risk of falling victim to ransomware.