.cosanostra Files Ransomware – How to Remove It

.cosanostra Files Ransomware – How to Remove It

This blog post has been made with the main goal to help you understand what is the .cosanostra file ransomware and how you can remove this cryptovirus effectively from your computer plus how you can try and restore files, encrypted by it on your PC.

A new variant of GarrantyDecrypt ransomware virus was recently detected to set the .cosanostra file extension to the files of the computers that have been attacked by it. The ransomware then adds the #RECOVERY_FILES#.txt ransom note which aims to ask victims to contact the crooks on the cosanostra19@protonmail.com address in order to pay for a decryption key. If your computer is infected with the .cosanostra files virus, we suggest that you read this article thoroughly to understand more about the .cosanostra variant of GarrantyDecrypt ransomware and learn ways via which you can attempt to remove this infection.

Threat Summary

Name.cosanostra Files Virus
TypeRansomware, Cryptovirus
Short DescriptionAims to scramble the files on the computers that are compromised by it and then ask victims to pay for decryption.
SymptomsFiles can not be opened and have the .cosanostra suffix added. A ransom note, called #RECOVERY_FILES#.txt is added.
Distribution MethodSpam Emails, Email Attachments, Executable files
Detection Tool See If Your System Has Been Affected by .cosanostra Files Virus


Malware Removal Tool

User ExperienceJoin Our Forum to Discuss .cosanostra Files Virus.
Data Recovery ToolWindows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive.

.cosanostra Files Virus – Distribution

For the .cosanostra file ransomware to be spread onto computers, the virus may be uploaded as a seemingly legitimate program on several websites, among which may be:

  • Cracks.
  • Patches.
  • Installers.
  • Portable executables.

The ransomware may also infect victims by being sent to them via e-mail attachments that only seem to be legitimate at first glance. They usually pretend to be:

  • Documents.
  • Invoices.
  • Receipts.
  • Banking statements.
  • Letters of complain.
  • Some work-related files.

The documents added are usually infected Microsoft Word files, which can compromise your computer via malicous macros after you open them.

GarrantyDecrypt .cosanostra Ransomware – Analysis

Once your computer has already been compromised by

GarrantyDecrypt ransomware, the virus may immediately start to create multiple different types of files. That may be located in the following Windows directories:

  • %AppData%
  • %Local%
  • %LocalLow%
  • %Roaming%
  • %Temp%

Once GarrantyDecrypt ransomware is already installed, the virus may begin to perform various malicious tactics. The first one is to drop it’s ransom note file, called #RECOVERY_FILES#.txt and make it so that you can see it everywhere on the compromised computer by modifying it to possibly auto open. The ransom note has the following message to victims:

All your files have been encrypted!

Now you should send us email with your personal tdentifier.

This email will be as confirmation you are ready to pay for decryption key.
You have to pay for decryption in Bitcoins. The price depends on fast you write to us.
After payment we will send you the decryption tool that will decrypt al? your files. Contact us
using this email address
cosanostral9@protonmail. com
And tell us your unique ID

The ransomware may also modify the Run and RunOnce sub-keys in Windows Registry editor in order to set malicious files to start automatically on Windows boot:

→ HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

Furthermore, the .cosanostra files virus may also delete the backed up shadow copies on the compromised machine by performing privilege escalation and then running the following commands on Windows Boot:

→ sc stop VVS
sc stop wscsvc
sc stop WinDefend
sc stop wuauserv
sc stop BITS
sc stop ERSvc
sc stop WerSvc
cmd.exe /C bcdedit /set {default} recoveryenabled No
cmd.exe /C bcdedit /set {default} bootstatuspolicy ignoreallfailures
C:\Windows\System32\cmd.exe” /C vssadmin.exe Delete Shadows /All /Quiet

.cosanostra Files Virus Encryption Process

To encrypt files, the .cosanostra ransomware may first perform a scan of the infected machine:


Then, the .cosanostra file ransomware may encrypt all files that are outside the following system directories:

  • %Windows%
  • %System%
  • %AppData%
  • %Temp%

The ransomware may add the .cosanostra file extension and the encrypted files may begin to appear like the following:

Remove .cosanostra Files Virus and Try Restoring Data

If you want to remove the .cosanostra files virus, we strongly recommend that you follow the removal instructions that are posted underneath. They are separated so that you can try to manually remove the .cosanostra files ransomware from your computer and if you fail in doing so, you can do it automatically, prefferably by downloading an advanced anti-malware software, which is the reccomended removal method of doing so. Such software will automatically remove all related files to .cosanostra ransomware and make sure your system does not get infected in the future too.

Furthermore, if you want to try and restore files, encrypted by the .cosanostra file ransomware, we would strongly recommend that you see the recovery methods underneath. They have been created to be of assistance to you so that you can try and restore as many files as possible on your computer, but they are not guarantee to recover all your data.


Ventsislav Krastev

Ventsislav has been covering the latest malware, software and newest tech developments at SensorsTechForum for 3 years now. He started out as a network administrator. Having graduated Marketing as well, Ventsislav also has passion for discovery of new shifts and innovations in cybersecurity that become game changers. After studying Value Chain Management and then Network Administration, he found his passion within cybersecrurity and is a strong believer in basic education of every user towards online safety.

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Windows Mac OS X

How to Remove .cosanostra Files Virus from Windows.

Step 1: Boot Your PC In Safe Mode to isolate and remove .cosanostra Files Virus


Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your PC with SpyHunter

Keep in mind, that SpyHunter’s scanner is only for malware detection. If SpyHunter detects malware on your PC, you will need to purchase SpyHunter's malware removal tool to remove the malware threats. Read our SpyHunter 5 review. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria

1. Hold Windows key() + R

2. The "Run" Window will appear. In it, type "msconfig" and click OK.

3. Go to the "Boot" tab. There select "Safe Boot" and then click "Apply" and "OK".
Tip: Make sure to reverse those changes by unticking Safe Boot after that, because your system will always boot in Safe Boot from now on.

4. When prompted, click on "Restart" to go into Safe Mode.

5. You can recognise Safe Mode by the words written on the corners of your screen.

Step 2: Uninstall .cosanostra Files Virus and related software from Windows

Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:

1. Hold the Windows Logo Button and "R" on your keyboard. A Pop-up window will appear.

2. In the field type in "appwiz.cpl" and press ENTER.

3. This will open a window with all the programs installed on the PC. Select the program that you want to remove, and press "Uninstall"
Follow the instructions above and you will successfully uninstall most programs.

Step 3: Clean any registries, created by .cosanostra Files Virus on your computer.

The usually targeted registries of Windows machines are the following:

  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

You can access them by opening the Windows registry editor and deleting any values, created by .cosanostra Files Virus there. This can happen by following the steps underneath:

1. Open the Run Window again, type "regedit" and click OK.

2. When you open it, you can freely navigate to the Run and RunOnce keys, whose locations are shown above.

3. You can remove the value of the virus by right-clicking on it and removing it.
Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.

Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.

Step 4: Scan for .cosanostra Files Virus with SpyHunter Anti-Malware Tool

1. Click on the "Download" button to proceed to SpyHunter's download page.

It is recommended to run a scan before purchasing the full version of the software to make sure that the current version of the malware can be detected by SpyHunter. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria.

2. After you have installed SpyHunter, wait for it to update automatically.


3. After the update process has finished, click on the 'Malware/PC Scan' tab. A new window will appear. Click on 'Start Scan'.


4. After SpyHunter has finished scanning your PC for any files of the associated threat and found them, you can try to get them removed automatically and permanently by clicking on the 'Next' button.


If any threats have been removed, it is highly recommended to restart your PC.

Step 5 (Optional): Try to Restore Files Encrypted by .cosanostra Files Virus.

Ransomware infections and .cosanostra Files Virus aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.

1. Download the reccomended Data Recovery software by clicking on the link underneath:

If the above link does not work for you and your region, try the other two links below, that lead to the same product:


2. On the download page, click on the "Download" button:

3. Click on "Save File" button:

4. Accept all agreements and click "Next":

5. After all the "Next" steps, click on "Install" and then wait for the installation to complete:

6. Run the software. Click on the location to scan for missing or deleted files and click on "Scan":

7. Wait for the scan to complete, it may take some time. Be advised that this scan is not 100% guaranteed to recover all files, but it does have some chance to get your data back:

Windows Mac OS X

Get rid of .cosanostra Files Virus from Mac OS X.

Step 1: Uninstall .cosanostra Files Virus and remove related files and objects

Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your Mac with SpyHunter for Mac
Keep in mind, that SpyHunter for Mac needs to purchased to remove the malware threats. Click on the corresponding links to check SpyHunter’s EULA and Privacy Policy

1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:

2. Find Activity Monitor and double-click it:

3. In the Activity Monitor look for any suspicious processes, belonging or related to .cosanostra Files Virus:

Tip: To quit a process completely, choose the “Force Quit” option.

4. Click on the "Go" button again, but this time select Applications. Another way is with the ⇧+⌘+A buttons.

5. In the Applications menu, look for any suspicious app or an app with a name, similar or identical to .cosanostra Files Virus. If you find it, right-click on the app and select “Move to Trash”.

6: Select Accounts, after which click on the Login Items preference. Your Mac will then show you a list of items that start automatically when you log in. Look for any suspicious apps identical or similar to .cosanostra Files Virus. Check the app you want to stop from running automatically and then select on the Minus (“-“) icon to hide it.

7: Remove any left-over files that might be related to this threat manually by following the sub-steps below:

  • Go to Finder.
  • In the search bar type the name of the app that you want to remove.
  • Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
  • If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.

In case you cannot remove .cosanostra Files Virus via Step 1 above:

In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:

Disclaimer! If you are about to tamper with Library files on Mac, be sure to know the name of the virus file, because if you delete the wrong file, it may cause irreversible damage to your MacOS. Continue on your own responsibility!

1: Click on "Go" and Then "Go to Folder" as shown underneath:

2: Type in "/Library/LauchAgents/" and click Ok:

3: Delete all of the virus files that have similar or the same name as .cosanostra Files Virus. If you believe there is no such file, do not delete anything.

You can repeat the same procedure with the following other Library directories:

→ ~/Library/LaunchAgents

Tip: ~ is there on purpose, because it leads to more LaunchAgents.

Step 2: Scan for and remove .cosanostra Files Virus files from your Mac

When you are facing problems on your Mac as a result of unwanted scripts and programs such as .cosanostra Files Virus, the recommended way of eliminating the threat is by using an anti-malware program. Combo Cleaner offers advanced security features along with other modules that will improve your Mac’s security and protect it in the future.

Step 3 (Optional): Try to Restore Files Encrypted by .cosanostra Files Virus on your Mac.

Ransomware for Mac .cosanostra Files Virus aims to encode all your files using an encryption algorithm which may be very difficult to decode, unless you pay money. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files, but only in some cases. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.

1. Download the recommended Data Recovery Mac app by clicking on the link underneath:

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