The Cdaz virus, known as a ransomware, is part of the STOP family. This malware family is known for malignant file encryption operations. Once the Cdaz virus gets into a system, it scans the system for files such as photos, videos, documents, and more. It modifies the file structure and adds the “.cdaz” extension to each encrypted file, making them unusable without the decryption.
Cdaz Virus Overview
Cdaz
🤔 Cdaz virus is ransomware that originates from the DJVU/STOP family. Its main target is to encrypt files that are important to you. After that this ransomware asks for a ransom fee – ($490 – $980) in Bitcoin.
The Cdaz virus is a type of malware that ciphers your files and forces you to pay for their restoration. This ransomware ciphers different file types. Encrypted files can be identified by a distinct “.cdaz” extension. The files touched by ransomware become impossible to access and use.
After that, the ransomware demands a file decryption payment in Bitcoin from the victims, that ranges from $490 to $980, depending on the time passed after the attack. Typically, a text file with ransom payment guidances is named as “_readme.txt“.
Cdaz Ransomware works with Salsa20 encryption algorithms to scramble the contents of the targeted files. Since Cdaz virus uses such a strong ciphering method, it becomes quite hard, if not impossible, to pick the decryption key without the assistance of the attackers.
Once Cdaz malware finishes the encryption, it shows a ransom note to the victim, asking for a ransom payment for the decryption key. The ransom note provides instructions on the ways of making the payment and often includes threats of system wipeout or ransom amounts surge if the demands are not met within a specified timeframe.
I have created an all-encompassing list of the solutions, tips, and methods to disable the Cdaz ransomware and decrypt and recover your files. There are situations when you can decrypt the files, while sometimes, it may be impossible.
📌 Important Reminder!
It is critical to say that paying the ransom does not guarantee the successful recovery of your files. The scoundrels who stand behind the Cdaz virus are not trustworthy. There were the cases where victims have paid the ransom, only to be denied by the cybercriminals with the decryption key provision.
Cdaz employs a unique key for every victim, with one exception:
The Cdaz virus is highly similar to other DJVU ransomware samples like Isak, Cdmx, Cdqw, and Lomx. This virus encrypts a wide range of common file types and appends its distinct “.cdaz” extension to all files. For instance, a file named “1.jpg” would be altered to “1.jpg.cdaz” and “2.png” to “2.png.cdaz“.
Upon successful encryption, the virus creates a special text file named “_readme.txt” and places it in every folder containing the encrypted files. It also adds the readme file to the desktop, so the victim will not miss its appearance even without opening folders.
The image below provides a visual representation of files with the “cdaz” extension:
Encrypted Files by STOP/DJVU Ransomware
| Name | Cdaz Virus |
| Ransomware family1 | DJVU/STOP2 ransomware |
| Extension | .cdaz |
| Ransomware note | _readme.txt |
| Ransom | From $490 to $980 (in Bitcoins) |
| Contact | [email protected], [email protected] |
| Detection | Trojan:MSIL/AgentTesla.NMR!MTB, Trojan:Win64/Grandoreiro!pz, Ransom:MSIL/BlackBit.MA!MTB |
| Symptoms |
|
| Fix Tool |
To remove possible malware infections, scan your PC:
6-day free trial available. |
This message asking payment is for restore files via decryption key:
_readme.txt (STOP/DJVU Ransomware) – The scary alert requesting users to pay the ransom to decrypt the encoded data contains these annoying cautions.
Cdaz ransomware arrives as a set of operations that are needed to perform certain tasks on a victim’s computer. One of the initial ones being launched is winupdate.exe, a deceptive process that shows a fake Windows update notification during the attack. That is needed to convince the victim that a sudden computer slowdown is caused by a Windows update.
Meanwhile, the ransomware runs another process (usually named by four random characters) which starts scanning the PC for target files and encrypting them. Next, the ransomware deletes Volume Shadow Copies from the system by the following CMD command:
vssadmin.exe Delete Shadows /All /Quiet
Once removed, it becomes virtually impossible to retrieve the previous computer state using System Restore Points. The problem is, ransomware operators are eliminating any built-in Windows methods that could assist the victim to recover files for free. In addition, the hackers modify the Windows HOSTS file by including a list of domains to it and directing them to the localhost IP. As a result, the victim will face a DNS_PROBE_FINISHED_NXDOMAIN error when trying to access one of the blacklisted websites.
It has come to our attention that ransomware endeavors to block websites that publish various how-to guides for computer users. It is obvious that by limiting specific domains, the crooks are trying to prevent the victim from reaching relevant and helpful ransomware-attack-related information online. This malware also stores two text files on the victim’s computer that offer attack-related information – the victim’s public key and personal ID. These two files are named bowsakkdestx.txt and PersonalID.txt.
After all these modifications, the malware doesn’t cease. Variants of STOP/DJVU have a tendency to deploy Vidar password-stealing Trojan on compromised systems. This threat possesses an extensive list of capabilities, including:
- Infiltrating the victim’s computer with malware and executing it to gain unauthorized access.
- Obtaining unauthorized access to login credentials of Steam, Telegram, and Skype.
- Manipulating and viewing files on the victim’s computer without their knowledge.
- Stealing cryptocurrency wallets from the victim’s system.
- Granting the hackers remote control over the victim’s computer for various malicious activities.
- Extracting sensitive information such as browser cookies, saved passwords, and browsing history.
The encryption algorithm used by DJVU/STOP virus is AES-256. So, if your data got encrypted with an online decryption key, the chances to get your files back without paying the ransom are quite low. Thing is, the key is unique for each victim, and finding a suitable one will take too much time.
Getting the online decryption key in another way is also merely impossible. It is stored on a server controlled by the crooks who spread the Cdaz malware. For receiving decryption key the payment should be $980. To see the payment details, the victims should contact the hackers 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
How To Remove STOP/Djvu Ransomware?
Video Guide
How To Decrypt .cdaz Files?
How to restore big files?
Try deleting .cdaz extension on a few big files and opening them. This malware has issues with large files encryption. Either the virus read and did not lock the file, or it bugged and did not add the filemarker. If your files are very large (2GB+), such a situation is highly probable. 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 Isak, Cdmx, Cdqw etc.
As a consequence of the modifications made by the criminals, STOPDecrypter is no longer backed. It has been replaced with the Emsisoft Decryptor for STOP Djvu Ransomware developed by Emsisoft.
You can download free decryption tool here: Decryptor for STOP Djvu.
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Select folders for decryption.
Based on the default configurations, the decryptor will by default choose the available directories in order to decrypt the currently available drives (the connected ones), including the network drives. You can choose other locations with the “Add” button.
Decryptors usually offer several options depending on the specific malware family. The present possible options are displayed in the Options tab and can be activated or disabled there. You may locate a comprehensive list of the currently active Options below.
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Click on the “Decrypt” button.
As soon as you 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 messages here if you need to do so.
The Emsisoft Decryptor might display different messages after a failed attempt to restore your files:
✓ Error: Unable to decrypt file with ID: [your ID]
Emsisoft does not have a corresponding key in the database.
✓ No key for New Variant online ID: [your ID]
Notice: this ID appears to be an online ID, decryption is impossible
Your original files were encrypted with an online key. There is no one to share the decryption key with you. File recovery without paying the ransom is impossible. 🙁
✓ Result: No key for new variant offline ID: [example ID]
This ID appears be an offline ID. Decryption may be possible in the future.
Malware used an offline key, but files could not be restored (the offline decryption key isn’t available yet). Nonetheless, this message is a good news for you, because it is possible to restore your files in the future. 🙂
It can take a few weeks or months until the decryption key gets found and uploaded to the decryptor. Please follow updates regarding the decryptable DJVU versions here.
✓ Remote name could not be resolved
It’s an indication of a DNS issue on your PC. Consider resetting your HOSTS file to default.
How to Restore .cdaz Files?
In some case ransomware is not doom for your files…
The Cdaz ransomware encryption mechanism is next: it encodes every file byte-by-byte, then saves a duplicate, erasing (not overriding!) the original file. Hence, the data of the file placement on the disk drive is lost, but the original file is not deleted from the disk. The cell, or the sector where this file was stored, can still hold this file, but it is not present in the file system and can be rewritten by data that has been loaded to this drive after the removal. Hence, it is possible to restore your files using special software.
Anyway, after realizing it was an online algorithm, it is impossible to retrieve my encrypted files. I also had my backup drive plugged in at the time of the virus, and this was also infected, or so I thought. Every folder within my backup drive had been infected and was encrypted. However, despite losing some important files, I retrieved almost 80% of my 2TB storage.
When I started going through the folders, I noticed the readme.txt ransom note in every folder. I opened some of the folders and found that all files that were not in a subfolder within that folder had been encrypted. However, I found a flaw and glimmer of hope when I went into the subfolders in other folders and found that these files had not been encrypted. Every folder within my c and d drives, including subfolders, had been encrypted, but this was not the case with the backup drive. Having subfolders created within a folder has saved 80% of my data.
As I said, I believe this to be only a small loophole on a backup drive. I’ve since found a further 10 % of my data on another hard drive on a different pc. So my advice is if you use a backup drive, create subfolders. I was lucky, I guess. But I was also unlucky that the virus hit as I was transferring some files from my backup.
Hopefully, this can help some other people in my situation.
Jamie NewlandRecovering your files with PhotoRec
PhotoRec is an open-source program, which is initially created for file retrieval from damaged disks, or for file retrieval in case if they are unintentionally deleted. However, as time has gone by, this program got the ability to retrieve the files of 400 different extensions. Hence, it can be used for data recovery after the Cdaz attack.
First, you need to download this app. It is 100% free, but the developer states that there is no assurance that the files will be restored. PhotoRec is distributed together with other program of the same developer – TestDisk. The program archive will bear TestDisk name, but don’t worry. PhotoRec files are right inside.
To run PhotoRec, you need to find and open “qphotorec_win.exe” file. No setup is required – the program has all the files it need within the archive, hence, you can fit it on your USB drive, and help your friends/parents/anyone who has been attacked by Cdaz ransomware.
After the launch, you will witness the screen showing you the entire list of your disks. However, this data is presumably useless, because the required menu is placed a bit higher. Click this tab, then choose the disk which was attacked by ransomware.
After opting for the disk, you need to opt for the destination folder for the restored files. This menu is located at the lower part of the PhotoRec window. The best decision is to export them on USB drive or any other type of removable disk.
Then, you need to specify the file formats. This feature is located at the bottom, too. As it was mentioned, PhotoRec can recover the files of about 400 different formats.
Finally, you can initiate files retrieval by pressing the “Search” button. You will observe the screen where the results of the scan and recovery are shown.
Cdaz files recovery Video Guide.
Frequently Asked Questions
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