Cosw Ransomware is a data locker malware and a variant of Stop/Djvu group. It encrypts files on the targeted PC by adding “.cosw” file virus extension to all files. For example, the file “monthlyreport.xls” will get changed after the ransomware attack into “monthlyreport.xls.cosw”. It will be an encrypted version of original file and cannot be opened without the decryption key.
After encryption of files, it leaves a note “_readme.txt” in all compromised folders. This note contains a ransom demand and instructions to unlock the files. Attackers demand $980 as ransom money to provide decryption tools. This guide can help you delete this virus and restore your files without paying the ransom money.
What is Cosw Ransomware?
Cosw Ransomware is another recently found ransomware-type malware infection that belongs to STOP/DJVU family. This dubious threat is a new variant of a long-lasting file-encrypting virus that uses a powerful algorithm to encode files on the infected computer. The primary motive of the creators of this virus is to extort money from users in return for the decryption tool.
Cosw File Virus is able to attack all versions of Windows computers without users’ permission. Upon infiltration, it runs a powerful encryption algorithm to lock all personal files of the victim. After encoding files, it also leaves a ransom note “_Readme.txt” on the infected system to ask for the ransom money. This dubious virus scares users by saying that their files can only be unlocked by the decryption tool. All the files on the targeted PC will become useless and a copy of the ransom note can be found in every folder.
Encryption of Data on infected PC
Cosw Ransomware basically performs asymmetric encryption on a compromised PC using powerful military-grade encryption software that generates a unique decryption key for every computer. These unique keys are stored on a remote server and are vital for the restoration of encrypted files. There is no way to access files encrypted by Cosw file virus without that key. Needless to say that every PC needs its own key to unlock files. This nasty virus can encrypt all types of files like videos, images, audio, documents, database, or almost every file typically stored on a personal computer.
If you store important and sensitive documents on your PC then you must keep a backup of your files on any external USB drive or cloud drive. Because once your system is infected by a threat like this, then it could a be a very serious problem. Most of the time, encryption like this is unbreakable or sometimes files also get corrupted. To avoid losing any important documents it is highly recommended to make backup copies.
Cosw File Virus and decryption of files
The decryption of files encrypted by .Cosw File Virus completely depends on obtaining the decryption key. Although attackers are offering the decryption tool for a price which might be the easiest way to restore your data. But you can’t trust cybercriminals to keep their word once they get paid. They will have no motivation whatsoever to decrypt your files. It completely depends on their morals if they want to give you a decryptor or not, once you pay the price. However, we strongly advise victims to not pay ransom money to avoid any scam.
In fact, we have got many reports where victims did not get the decryption tool after paying the money. Your computer is already infected by Cosw file virus, all your files are encrypted and you should not risk your money too. Cybercriminals are only interested in financial benefits and they might re-encrypt your files by releasing new variants. If they once get money from you, they can also attack your system again to make more money.
Ransom Note “_readme.txt” is left on PC
As we have already mentioned, after encrypting your files, Cosw Ransomware will leave a ransom note on your computer. It is the standard practice of all file-encrypting malware to extort money from victims. You can also find that ransom note in all the compromised folders. This note contains a text message claiming that there is no other way of restoring files. Attackers will also offer free decryption of 1 file as proof and ask users to pay the price to decrypt all files.
The base price of decryptor for Cosw Ransomware is set $980 USD. Makers of this virus are offering a 50% discount if victims will pay the ransom money within 72 hours. They suggest users take the deal and pay $490 USD through Bitcoin. Victims are said to contact virus creators through emails provided in ransom note to get the decryption tool.
Ransom note (_Readme.txt) contains the following text message :
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-Oc0xgfzC7q 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@example.com Reserve e-mail address to contact us: firstname.lastname@example.org Your personal ID: -
Cybercriminals are demanding money through bitcoin which cannot be traced and chances are you will lose your money. So it is important that you first try alternative methods to recover your files and avoid unnecessary risk of financial loss.
If you have made backup copies of your important files then you can restore your data without paying ransom money. But first, you will need to delete this nasty ransomware completely from your system or it will keep encrypting your files.
Cosw Ransomware: Threat Analysis
Distribution methods of this type of malware
It is safe to say that you have not downloaded this malware on your computer knowing that it will encrypt all your files. So it must have been sneaking into your system without permission through deceptive tricks. Creators of malware like Cosw file virus use various tricks to deploy their creation. The use of spam email attachments is one of the most used and effective methods. So don’t open any suspicious email from an unknown sender and don’t open email attachments before scanning for viruses.
Software bundling is also a very common method where creators of freeware programs allow third-party attachments. This kind of file may carry harmful programs that can get installed in the background without asking for permission. Downloading pirated or cracked software from torrents and suspicious sites may bring .Cosw file virus on your computer. Clicking on suspicious links or visiting porn sites or sharing files on an unsafe network could also expose your PC to threats. We have created a list of precautionary measures which can help you avoid malware in the future, you can see it at the end of this guide.
How to get your file back?
If you want to get back your encrypted files then you need to first remove it completely. If this nasty malware is not removed, it will keep encrypted your files. Do not format your computer or Re-install Windows because you will not be able to decrypt your files then.
So in my professional opinion, you must use a powerful Anti-malware Tool. Once you successfully remove this infection, then try to recover your files through backup. If you don’t have any backup then you can try using a good Data Recovery software to see if can find previous versions of files encrypted by Cosw Ransomware. We have created a guide to help you remove this infection, just follow the steps mentioned below.
How To Remove Cosw File Virus
Automatic Cosw Ransomware Removal Guide
It can be hectic to remove threats from an infected PC but the use of powerful Anti-Malware can make it quite easy. SpyHunter anti-malware can help you to remove Trojan, Ransomware, Spyware, Adware, PUPs, etc. easily. You can scan your system for Cosw file virus and all other hidden threats at once. All you need to do is to download this software and run a new scan on your PC.
It will find all the threats and viruses in no time and save you lots of time and effort. This amazing software also provides 24X7 customer support and one-on-one Spyware HelpDesk support for Custom Malware removal. Advanced System Guard feature detects and removes threats in real time. It has a very User-Friendly Interface and regular Malware definition updates make it most effective against the latest attacks.
How SpyHunter 5 Anti-Malware Works
- You will begin by downloading the software on your system for which you have to click on the below download button.
- Once the software has been downloaded, double-click on SpyHunter-Installer.exe to install the Anti-Malware program on your PC and proceed with the setup.
- After installation, you will need to launch the Anti-Malware application. From the welcome screen click on the Start Scan Now button to initiate a new scan of your PC.
- Once the scanning process begins, it will take some time to run a thorough diagnostic of your PC and find all hidden threats and malware.
- Soon you will find a complete list of all the threats on your system screen. Then you will need to click on the Next button to delete all the viruses.
How To Decrypt .Cosw Files
As there is no Cosw ransomware decryptor available, you will need to use alternate options to restore your files. The first one is to use the backup. If you have created a backup of your important files then it is going to be quite easy. However, if you don’t have any backup files or they also got encrypted by the virus then you will have to try a data recovery software.
We recommend using Stellar Data Recovery software because it is a powerful and trusted data recovery software. Paying ransom money is not ideal because it will only motivate hackers to carry out more attacks. You can wait for any free decryptor to be launched but it can take forever. Download the free trial version of data recovery and scan your PC for files. It may be able to recover some of your files and save you lots of money.
- Click on the below download button to get started instantly with the data recovery process on your PC.
- After the download click on the installer file and complete the software installation. Then launch the application and select the Data type to recover, and click the Next button.
- After the selection of data, you will need to select the location from where you want to recover data. Choose the location and then click on the Scan button.
- The software will take some time to scan your system. You will see a list of all the files that can be recovered. You can preview them or click on the Recover button to save them.
Manual Cosw File Virus Removal Guide
Start PC in safe mode with networking
- Click on the Windows and R keys together on your keyboard to open the Windows Run Box.
- Now you will need to type in MSConfig and then click the OK button.
- The System configuration settings box will appear on your computer screen.
- Click on the Boot tab, check the Safe Boot option, and select the network box,
- Finally, you will have to click on Apply and then press the OK button.
Kill Malicious Process From Task Manager
- Open the Windows Rub box again on your PC by pressing the Windows and R keys together on your keyboard.
- This time you will have to type in taskmgr and then click the OK button to open Windows Task Manager. Look for any unknown or malicious running on your system.
- Select the process which is taking lots of systems resources and then click on the End Task button.
Uninstall Cosw Ransomware from Control Panel
- Again you will need to open the Windows Run Box, so press the Windows and R keys together.
- This time you need to open the Windows Control Panel, so type in appwiz.cpl and then click the OK button.
- Programs and Features windows will appear on your computer screen with a list of all the installed applications.
- Now you need to look for any unknown or virus related program and then Uninstall it from your PC.
Remove Cosw Ransomware From Registry Editor
- Again open the Windows Run Box on your PC by using the Windows and R keys.
- To open the Windows Registry Editor, type in Regedit and click the OK button.
- Now you will have to find the virus related registry files and remove them.
- Press CTRL and F keys together on the keyboard to start a Find query.
- Type the virus name and click on Find Next button to find malicious entries and delete them.
Remove Malicious IP addresses from Windows Hosts Files
- To open the Windows hosts file, simply press the Windows and R keys together on the keyboard.
- Type C:\Windows\System32\drivers\etc in Run Box and then click the OK button.
- Now you will need to access the Windows hosts file using Notepad.
- Most threats add malicious IP addresses here to automatically connect to remote servers.
- Delete all the malicious IP addresses below the localhost and save the file.
Delete Virus related files from your PC
When malware infects your system, it normally creates several malicious files and spread them at different locations. After you remove the malware, these leftover files help them to get back to your computer. Remove all virus related files at once by following the below instruction :
- Open the Windows Run Box again by using the Windows and R keys together.
- Now you will open the below paths one by one using the Run Box and remove malicious files.
For the first four options, look for any recent folder related to the Cosw File Virus and remove them. For the Temp folder, you can delete all the files at once. Use Ctrl, Shift, and Delete keys together for permanent removal.
Remove Cosw File Virus via system restore
- You will again need the Windows Run Box, so press the Windows and R keys together.
- Open the Command Prompt by typing in cmd and then clicking the OK button.
- Type cd restore and press Enter, then type rstrui.exe and press Enter.
- The System Restore window will get opened instantly then click on the Next button.
- Choose a System Restore point you have created in the past and click the Next button.
- Finally, when you will hit the Yes button, the system restoration process with start immediately.
Note: System restore to remove a virus will only work if you have a restore point set on your PC. Otherwise, no changes will be made to your system and it will not remove any threats. Be advised, restoring the computer to a previous version does not always guarantee virus removal. Most viruses delete restore points, so don’t get disappointed if this trick does not work for you.