Removal of Cezor ransomware infection

Also Known As: Cezor virus
Distribution: Moderate
Damage level: Severe

Cezor ransomware removal instructions

What is Cezor?

Belonging to Djvu ransomware family, Cezor is a high-risk ransomware infection discovered by Petrovic. Once infiltrated, Cezor encrypts most of stored files and appends filenames with ".cezor" extension (e.g., "sample.jpg" is renamed to "sample.jpg.cezor"). Encrypted data instantly becomes unusable. Once encryption is over, Cezor generates a text file ("_readme.txt") and drops a copy in every existing folder.

The created text file delivers the exact same message as the one delivered by most of other ransomware infections from Djvu family. It basically states that data is encrypted and that a unique decryption key is necessary to restore it. Unfortunately, this is true. The type of cryptography used by Cezor is currently unknown. However, it is sure that each victim gets a unique decryption key and it is impossible to restore files without it. The problem is that victims cannot access their keys, as all of them are stored in a remote server controlled by Cezor's developers (cyber criminals). In order to receive their keys and restore data victims have to pay a ransom of $980. In order to receive payment/decryption instructions victims must contact developers via provided email addresses or telegram. It is noted that victims who'll contact crooks within 72 hours after the encryption will receive a 50% discount (the price will drop to $490). Additionally, victims are allowed to attach one selected file which will be restored and sent back as a guarantee that decryption is actually possible and that these persons can be trusted. Nevertheless, we strongly advise you to never do so. Cyber criminals are notorious for ignoring victims, once payments are submitted. For this reason, paying usually gives no positive result and users merely get scammed. Be aware that Cezor is designed to encrypt data with a so-called "offline key" (which is hard-coded) whenever the infected device has no Internet connection or the server is not responding. For this reason, we highly recommend to try restoring with a decryption tool developed by Michael Gillespie. If that doesn't work, the only possible solution is to restore everything from a backup.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:

Cezor decrypt instructions

Internet is full of ransomware-type infections that share similarities with Cezor. Boooam, CAGO, JSWRM - these are only few examples from a long list. Although the developers are different, almost all of these infections behave exactly the same: encrypt data and make ransom demands. There typically are only two major differences: 1) type of used cryptography, and; 2) size of ransom. Unfortunately, ransomware infections typically employ algorithms like RSA, AES, and other that generate unique decryption keys. For this reason, it is virtually impossible to decrypt data without developers interference. The only possible scenarios are ransomware not being fully developed and/or having certain bugs (e.g., the key is hard-coded, stored locally, etc.) Ransomware is one of the main reasons why you should maintain regular data backups. However, keep in mind that locally stored backups will be compromised alongside with regular data, which is why you should store backups in remote server or unplugged storage device. Additionally, there's always a chance that used server/hardware will be damaged. For this reason,w e recommend to have multiple backup copies stored in different locations.

How did ransomware infect my computer?

Ransomware infections are typically proliferated using the following tools/methods: fake software updaters/cracks, trojans, email spam campaigns, and third party software download sources. Fake updaters infect computers by exploiting outdated software's bugs/flaws or simply downloading and installing malware rather than actual updates. Same goes for fake cracks which infect systems rather than providing users with access to paid software features. Trojans are basically malicious programs that stealthily infiltrate computers with an intention of injecting additional malware. Cyber criminals employ email spam campaigns to send thousands of emails consisting of malicious attachments (links/files) and deceptive messages encouraging recipients to open. Attachments are likely to be presented as some important documents - this is being done to create the impression of legitimacy and increase the chance of tricking recipients. Last but not least are unofficial software download sources, such as Peer-to-Peer (P2P) networks (e.g., eMule, torrents, etc.), freeware download/free file hosting sites, and similar. Cyber criminals use them to present malware as legitimate/genuine software, what tricks users into downloading and installing malware manually.

Threat Summary:
Name Cezor virus
Threat Type Ransomware, Crypto Virus, Files locker
Detection Names (A959.tmp.exe) Avast (Win32:Malware-gen), BitDefender (Trojan.GenericKD.41435343), ESET-NOD32 (A Variant Of Win32/Kryptik.GUKJ), Kaspersky (Trojan-Ransom.Win32.Stop.bb), Full List (VirusTotal)
Encrypted Files Extension .cezor
Ransom Demanding Message _readme.txt
Ransom Amount $980/$490
Cyber Criminal Contact gorentos@bitmessage.ch, verasto@firemail.cc, @datarestore (Telegram)
Symptoms Can't open files stored on your computer, previously functional files now have a different extension, for example my.docx.locked. A ransom demanding message is displayed on your desktop. Cyber criminals are asking to pay a ransom (usually in bitcoins) to unlock your files.
Additional Information This malware is designed to show fake Windows Update window, modify Windows "hosts" file (to prevent users from accessing cyber security websites) and inject AZORult trojan into the system.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password stealing trojans and malware infections can be installed together with a ransomware infection.
Removal

To eliminate Cezor virus our malware researchers recommend scanning your computer with Spyhunter.
▼ Download Spyhunter
Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

How to protect yourself from ransomware infections?

In order to prevent this situation users must firstly realize that the main reasons for computer infections are poor knowledge and reckless behavior. The key to its safety is caution, meaning that paying close attention during the download/installation/update processes, as well as when browsing the Internet in general is a must. Always be sure to download software only from official sources, preferably using direct download links (third party downloaders/installers are likely to include rogue apps, which is why such tools shouldn't be used). Same goes for software updates. Keep installed applications/operating system up-to-date. However, keep in mind that this should be achieved only through implemented functions or tools provided by the official developer. Software piracy is considered a cyber crime. Moreover, most of cracking tools are fake and, thus, the risk of infections is extremely high. For this reason, you should never attempt to crack any installed applications. Handle all email attachments with care. Files/links that are irrelevant and do not concern you should never be opened. Same goes for attachments received from suspicious/unrecognizable email addresses. Lastly, be sure to have a reputable anti-virus/anti-spyware suite installed and running at all times - software of this type is very handy, since it detects and eliminates most of infections before the system is harmed. If your computer is already infected with Cezor, we recommend running a scan with Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in Cezor ransomware's text file ("_readme.txt"):

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:
hxxps://we.tl/t-WbgTMF1Jmw
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:
gorentos@bitmessage.ch

Reserve e-mail address to contact us:
varasto@firemail.cc

Our Telegram account:
@datarestore
Mark Data Restore

Your personal ID:
-

Screenshot of files encrypted by Cezor (".cezor" extension):

Files encrypted by Cezor

Malware researcher Michael Gillespie has developed a decryption tool that might restore your data if it was encrypted using an "offline key". As we've already mentioned, each victim gets a unique decryption key and all of them are stored in remote servers controlled by cyber criminals. These are categorized as "online keys". However, there are cases when the infected machine has no Internet connection or the server is timing out/not responding. If that is the case, Cezor will use an "offline encryption key", which is hard-coded. Now it is worth mentioning that cyber criminals change offline keys every now and again. This is being done to prevent multiple encryptions with the same key. Meanwhile, Michael Gillespie continually gathers offline keys and updates the decrypter. However, the chances of successful decryption are still very low, since only a very small portion of "offline keys" has been gathered. You can download the decrypter by clicking this link (note that the download link remains the same, despite the fact that decrypter is being continually updated). Your files will be restored only if the list of gathered keys will include the one that was used to encrypt your data.

Screenshot of STOP/Djvu decrypter by Michael Gillespie:

STOP/Djvu ransomware decrypter by Michael Gillespie

As with most of ransomware from Djvu family, Cezor also displays a fake Windows update pop-up during the encryption:

Djvu ransomware family fake update

IMPORTANT NOTE! - Aside from encrypting data, ransomware-type infections from Djvu malware family also installs a trojan-type virus called AZORult, which is designed to steal various account credentials. Moreover, this malware family is designed to add a number of entries to the Windows hosts file. The entries contain URLs of various websites, most of which are related to malware removal. This is carried out with the intention of making users unable to access malware security websites and seek help. Our website (PCrisk.com) is also on the list. Removing these entries, however, is simple - you can find detailed instructions in this article (note that, although the steps are shown in the Windows 10 environment, the process is virtually identical on all versions of the Microsoft Windows operating system).

Screenshot of websites added to Windows hosts file:

Tro Ransomware adding websites to Windows Hosts file

Cezor ransomware removal:

Instant automatic removal of Cezor virus: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Spyhunter is a professional automatic malware removal tool that is recommended to get rid of Cezor virus. Download it by clicking the button below:
▼ DOWNLOAD Spyhunter By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the Cezor virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the Cezor ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining Cezor ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of Cezor are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by Cezor, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as Cezor ransomware.

Note that Windows 10 Fall Creators Update includes "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default this feature automatically protects files stored in Documents, Pictures, Videos, Music, Favorites as well as Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here's more information on how to get this update and add additional protection layer from ransomware infections.

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove Cezor ransomware:

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global virus and spyware activity level today:

Medium threat activity
Medium

Increased attack rate of infections detected within the last 24 hours.

QR Code
Cezor virus QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of Cezor virus on your mobile device.
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Platform: Windows

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