How to remove Coza Ransomware and decrypt .coza files

What is Coza Ransomware

Coza is a new ransomware sample developed by the notorious STOP/Djvu group of extortionists. Alike many other variants published by these cybercriminals, this one employs an almost identical encryption and extortion pattern. Upon settling down on an infected machine, the virus starts scanning and therefore encrypting potentially important pieces of data. By doing so, the virus aims to create more incentives for victims to pay for decryption proposed by the attackers. In addition to encryption, the malware also makes sure victims can differentiate locked from non-locked files – by simply assigning the .coza extension. For instance, a file previously named 1.xlsx will change to 1.xlsx.coza, 1.pdf to 1.pdf.coza and so forth with other targeted file types. To undo the encryption, victims are said to follow instructions within the _readme.txt text note.

Cybercriminals claim they are the only figures able to provide the necessary decryption software and unique key to return the files. The price for their decryption is set at $980, however, can be halved to $490 if swindlers are contacted within the first 72 hours after facing infection. Victims are instructed to write to one of the attached e-mail addresses (support@freshmail.top or datarestorehelp@airmail.cc) and include their personal ID. In addition, cybercriminals are also ready to showcase their decryption abilities. Infected users are allowed to send 1 non-valuable file and get it decrypted for free. Unfortunately, although ransomware developers are usually the only source of getting decryption keys for deciphering data, some of them fool their victims and do not provide the promised decryption tools/keys. Thus, trusting cybercriminals is always a risk that involves monetary loss and no promised result in return. STOP/Djvu variants (especially newer ones), are well-developed and do not contain as many bugs to allow third-party decryption. This is why the best way you can recover your data for free and without bearing any risks – is via backup copies. Note that removing Coza Ransomware is essential before attempting manual decryption – to make sure the file encryptor does not encipher more data or spread to neighboring networks. If you do not have an available backup and paying the ransom is not a risk you are willing to take, then it is still worth trying to use third-party recovery/decryption tools from our guide below. Follow our instructions to remove the malware and attempt manual recovery/decryption.

How Coza Ransomware infected your computer

Many cybercriminals (including those behind STOP/Djvu attacks) tend to infiltrate ransomware via phishing e-mail letters, pirated software, and malicious websites. With regard to fraudulent e-mail messages, threat actors camouflage them under the names of legitimate organizations, such as tax authorities, banks, delivery firms, and other kinds of trustworthy entities. Within such letters, users will usually be tricked into downloading and opening some malicious attachments disguised as genuine files (e.g., MS Office files, PDFs, Executables, JavaScript files, etc.). Once the malicious file is executed according to instructions, users risk getting infected with ransomware or trojans that will chain-deploy other infections onto the infected system. Note that the same infiltration pattern applies to almost all distribution channels. The primary goal of cybercriminals is to make an inexperienced or unattentive users download or install some malvertising file. To avoid this, it is recommended to be cautious with unfamiliar content, browser trusted websites, and download software only from official and legitimate sources. Read our guide below for more tips to protect yourself against such threats.

1. Download Coza Ransomware Removal Tool
2. Get decryption tool for .coza files
3. Recover encrypted files with Stellar Data Recovery Professional
4. Restore encrypted files with Windows Previous Versions
5. Restore files with Shadow Explorer
6. Restore media files with Media Repair
7. How to protect from threats like Coza Ransomware

Virus modifies “hosts” file to block Windows updates, downloading antivirus programs, and visiting sites related to security news or offering security solutions. Coza Ransomware comes along with AZORult trojan, which was initially created to steal logins and passwords. The process of infection also looks like installing Windows updates, the malware shows a fake window, that mimics the update process.

It uses rdpclip.exe to replace a legal Windows file and to launch an attack on a computer network. After encrypting the files, the encrypter is deleted using the delself.bat command file. Coza Ransomware virus is propagated via spam attack with malicious e-mail attachments and using manual PC hacking. Can be distributed by hacking through an unprotected RDP configuration, fraudulent downloads, exploits, web injections, fake updates, repackaged, and infected installers. The virus assigns a certain ID to the victims, which is used to name those files and supposedly to send a decryption key. Great tools to protect against Coza Ransomware are: Emsisoft Anti-Malware and Malwarebytes Anti-Malware.

How to remove Coza Ransomware manually

It is not recommended to remove Coza Ransomware manually, for safer solution use Removal Tools instead.

Coza Ransomware files:

_readme.txt
rdpclip.exe
delself.bat
{randomname}.exe

Coza Ransomware registry keys:

no information

How to decrypt and restore .coza files

Use automated decryptors

Download STOP Djvu Decryptor from EmsiSoft (.coza variations)

IMPORTANT: Read this detailed guide on using STOP Djvu Decryptor to avoid file corruption and time wasting.

STOP Djvu Decryptor is able to decrypt .coza files, encrypted by Coza Ransomware. This tool was developed by EmsiSoft. It works in automatic mode, but in most cases works only for files encrypted with offline keys. Download it here:

Dr.Web Rescue Pack

Famous antivirus vendor Dr. Web provides free decryption service for the owners of its products: Dr.Web Security Space or Dr.Web Enterprise Security Suite. Other users can ask for help in the decryption of .coza files by uploading samples to Dr. Web Ransomware Decryption Service. Analysis of files will be performed free of charge and if files are decryptable, all you need to do is purchase a 2-year license of Dr.Web Security Space worth $120 or less. Otherwise, you don’t have to pay.

If you are infected with Coza Ransomware and removed it from your computer, you can try decrypting your files. Antivirus vendors and individuals create free decryptors for some crypto-lockers. To attempt to decrypt them manually you can do the following:

Use Stellar Data Recovery Professional to restore .coza files

1. Download Stellar Data Recovery Professional.
2. Click Recover Data button.
3. Select type of files you want to restore and click Next button.
4. Choose location where you would like to restore files from and click Scan button.
5. Preview found files, choose ones you will restore and click Recover.

Using Windows Previous Versions option:

1. Right-click on infected file and choose Properties.
2. Select Previous Versions tab.
3. Choose particular version of the file and click Copy.
4. To restore the selected file and replace the existing one, click on the Restore button.
5. In case there is no items in the list choose alternative method.

Using Shadow Explorer:

1. Download Shadow Explorer program.
2. Run it and you will see screen listing of all the drives and the dates that shadow copy was created.
3. Select the drive and date that you want to restore from.
4. Right-click on a folder name and select Export.
5. In case there are no other dates in the list, choose alternative method.

If you are using Dropbox:

1. Login to the DropBox website and go to the folder that contains encrypted files.
2. Right-click on the encrypted file and select Previous Versions.
3. Select the version of the file you wish to restore and click on the Restore button.

Use Media Repair to decrypt media files encrypted with .coza

1. Download Media Repair tool.
2. Right-click on the downloaded archive, and select Extract to Media_Repair\.
3. Then double-click on the extracted .exe file to launch the utility.
4. At first, you have to choose which file type you want to decrypt. You can do it from the drop-down menu in the utility.
5. Next, browser the folder with encrypted or reference files. Choose any of them and click on the Test icon located in the top right corner.
6. Media Repair will display a pop-up message with information on whether it can repair the selected file or not.
7. After checking if it is possible or not, select your reference file and click on the icon right under the Test button we used in step #5.
8. If the file pair is properly matched, you can move on and hit the Play button to start repairing. You can also stop the process anytime by clicking on the Stop button.

How to protect computer from viruses, like Coza Ransomware, in future

1. Get special anti-ransomware software

Use ZoneAlarm Anti-Ransomware

ZoneAlarm Anti-Ransomware Dashboard

ZoneAlarm Anti-Ransomware Alert

ZoneAlarm Anti-Ransomware Blocked

Famous antivirus brand ZoneAlarm by Check Point released a comprehensive tool, that will help you with active anti-ransomware protection, as an additional shield to your current protection. The tool provides Zero-Day protection against ransomware and allows you to recover files. ZoneAlarm Anti-Ransomware is compatible with all other antiviruses, firewalls, and security software except ZoneAlarm Extreme (already shipped with ZoneAlarm Anti-Ransomware) or Check Point Endpoint products. The killer features of this application are: automatic file recovery, overwrite protection that instantly and automatically recovers any encrypted files, file protection that detects and blocks even unknown encryptors.

2. Back up your files

As an additional way to save your files, we recommend online backup. Local storage, such as hard drives, SSDs, flash drives, or remote network storage can be instantly infected by the virus once plugged in or connected to. Coza Ransomware uses some techniques to exploit this. One of the best services and programs for easy automatic online backup is iDrive. It has the most profitable terms and a simple interface. You can read more about iDrive cloud backup and storage here.

3. Do not open spam e-mails and protect your mailbox

Malicious attachments to spam or phishing e-mails are the most popular method of ransomware distribution. Using spam filters and creating anti-spam rules is good practice. One of the world leaders in anti-spam protection is MailWasher Pro. It works with various desktop applications and provides a very high level of anti-spam protection.