Cosw Virus Removal Guide (+Decrypt .cosw files)

Cosw – Ransomware

Cosw is a destructive software application functioning as common ransomware. Michael Gillespie, the popular malware researcher, first found this new name in the DJVU ransomware family.

Cosw was created for the sole purpose to encrypt all popular file types. Realistically, as quickly as the file encryption is successfully achieved, the users are unable to get access to them. Cosw ransomware adds its own “.cosw” to all the encrypted files. For example, the file “price_list.xls”, as soon as crypted by Cosw, will be titled as “price_list.xls.cosw”. When the file encryption is accomplished, Cosw puts its own distinct text document (_readme.txt) into all the folders that keep the encrypted files.

The message specified by document asking for the random os very similar to the alerts offered by other ransomware risks coming from the DJVU family. The warning basically shows that the information has been secured and the only solution to get access to it is to use an unique standalone key. Regretfully, this declaration is definitely true.

The method to secure the files utilized by Cosw is not completely researched. Nevertheless, there is no doubt that each computer system owner might be provided a special decryption key, which is absolutely special. It is extremely hard to recover the data without the suitable key in place.

“Don’t worry, you can return all your files!”, from _readme.txt message:

One more peculiarity of the Cosw ransomware is that the users are unable to get access to the key. The decrypting key is hosted on an unique server under the complete control by the crooks who have launched the Cosw virus into the world wide web. In order to acquire the key and restore the important information, the users are informed to connect with the frauds by means of e-mail or by telegram and to pay the ransom in the quantity of $980.

The message also states that the people ought to contact the Cosw authors within 72 hours upon the moment of the data encryption. The alert indicates that by doing so the people will obtain a 50% discount rate, for that reason, the ransom quantity falls to $490.

No matter what the amount of the ransom is, we strongly encourage that you do not pay the ransom. There is no warranty that these online scoundrels will keep their guarantees, so they might not care at all what the victims feel about the file encryption, even when the amount of the ransom is received into their accounts. Hence, paying ransom frequently does not lead to a successful healing. So, the users may just lose their money for absolutely nothing.

Similarly, we advise you not to contact the scams as they advise. Do not transfer cash into their wallets. There are no applications that might break the Cosw ransomware or bring back the information at no charge. Therefore, the only proper decision is to restore the information from possible backups (if readily available).

Virus Summary

Name Cosw Ransomware
File Extension cosw
Type Ransomware
Family DJVU
Short Description The ransomware encrypts all the data stored on your system and requires a ransom to be paid on your part supposedly to recover your important files.
Symptoms File encryption by the ransomware is performed by means of the AES-256 algorithm (CFB mode) encryption algorithm. Once the encryption is completed, the ransomware adds its special .cosw extension to all the files modified by it.
Distribution Method Adware bundles and software cracks
Similar Infections Lokas, Besub, Nusar
Cosw Removal Tool   GridinSoft Anti-Malware
Cosw Decryption Tool   Emsisoft Djvu Decryptor

Do not forget that the Web is now filled with infections comparable to the Cosw virus. For example, this particular danger is basically identical to Brusaf and other ransomware-type infections. These destructive energies have actually been established in order to encrypt the important information and reveal the demand for the users to pay the ransom. All these infections utilize the identical algorithm to generate the specific key for effective files decryption.

Unless the Cosw ransomware is still under the development procedure or has got some concealed bugs, it is not possible to bring back the information by hand. Hence, the only working solution to prevent the loss of your essential information is to frequently maintain updated backups of all your vital documents.

Another crucial piece of advice is to save the backups on unique storage not connected to your primary device. For instance, you might store it on the USB Flash Drive, or some external drive, or by using the cloud data storage services. Keeping the backups on your system drive is extremely dangerous, since the backup might also be encrypted by the Cosw .

Leakages for the Cosw ransomware attack.

Cosw utilizes lots of courses to infiltrate the vulnerable computer systems. It is not certain what particular technique was utilized in your case, however, the intrusion may take place by means of the following channels:

  • bundling with third-party programs, primarily free software;
  • spam emails from the unknown senders;
  • sites supplying free hosting;
  • P2P (peer-to-peer) torrent downloads.

There are times when the Cosw might camouflage itself as some authentic application, for instance, through the misleading alerts requiring setup of some software update. This is the most common technique utilized by the scams to inject the Cosw ransomware files into the system. This way users partly participate in its installation, without plainly comprehending the danger.

In addition, the frauds might send out unsolicited spam email with challenging informs encouraging the people to open dubious accessories or click some download links, for instance, those encouraging individuals to open specific pictures, text files, tax documents and other info.

No doubt, opening these files or clicking on the malicious links might essentially damage the system. Fake Acrobat Reader upgrade notices may result in the Cosw ransomware infiltration. Similarly, downloading the split software might furthermore consist of the ransomware installer. The last but not the least, installation of Cosw might happen through some Trojan horses that may be set up stealthily into the system and without the user’s direct consent or perhaps consent.

Avoiding the Cosw injection.

Of course, there is no outright guarantee that your computer will be always devoid of any malware attacks, nevertheless, we would like to share some helpful suggestions with you to make it more secure. Make sure to pay really very close attention while searching the web and especially while downloading cost-free programs. Do not open any dubious e-mail accessories, specifically if the sender is not known to you.

Do not forget that specific freeware installer may likewise consist of some other extra apps in the bundle. These extra applications might be very destructive. It is of utmost significance to keep your anti-virus software application and your os in general to be constantly correctly updated.

It is rather sensible that downloading cracked apps is unlawful, nevertheless, furthermore, such unapproved software usage may likewise bring serious damage to your PC. Hence, do not download any split programs. Plus, the reality that your existing anti-virus did not protect the system from the Cosw ransomware is an excellent reason for you to reevaluate your choices and switch to another program that can render the securing functions on a much better level.

Below please find the quotation from the Cosw text file:

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-2P5WrE5b9f
 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:
 restorealldata@firemail.cc

 Reserve e-mail address to contact us:
 gorentos@bitmessage.ch

 Our Telegram account:
 @datarestore

Screenshot of files with “.cosw” extension added by the virus:”

Use GridinSoft Anti-Malware to remove Cosw ransomware from your computer

1.Download GridinSoft Anti-Malware.

You can download GridinSoft Anti-Malware by clicking the button below:

  GridinSoft Anti-Malware

2. Double-click on the setup file.

When setup file has finished downloading, double-click on the setup-antimalware-ag.exe file to install GridinSoft Anti-Malware on your computer.

An User Account Control asking you about to allow GridinSoft Anti-Malware to make changes to your device. So, you should click “Yes” to continue with the installation.

3. Press Install button for run GridinSoft Anti-Malware.

3.Once installed, GridinSoft Anti-Malware will automatically run.

4. Wait for the GridinSoft Anti-Malware scan to complete.

GridinSoft Anti-Malware will automatically start scanning your computer for Win Speedup 2018 and other malicious programs. This process can take a 20-30 minutes, so we suggest you periodically check on the status of the scan process.

5. Click on “Clean Now”.

When the scan has completed, you will see the list of infections that GridinSoft Anti-Malware has detected. To remove them click on the “Clean Now” button in right corner.

Use Emsisoft Decryptor for restore cosw files

You can get Emsisoft Decryptor by clicking the button below:

  Emsisoft Decryptor

  1. Run the decryptor as an administrator. The license terms will show up, which you have to agree to by clicking the “Yes” button.
  2. Once the license terms are accepted, the primary decryptor user interface opens.
  3. By default, the decryptor will pre-populate the locations to decrypt with the currently connected drives and network drives. Additional locations can be added using the Add” button.
  4. Decryptors typically offer various options depending on the particular malware family. The available options are located in the Options tab and can be enabled or disabled there. You can find a detailed list of the available Options below.
  5. After you have added all the locations you want to decrypt to the list, click the “Decrypt” button to start the decryption process. The screen will switch to a status view, informing you about the current process and decryption status of your files
  6. The decryptor will inform you once the decryption process is finished. If you require the report for your personal records, you can save it by clicking the “Save log” button. You can also copy it straight to your clipboard to paste it into emails or forum posts if you are asked to.
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Daniel Zimmermann

Daniel Zimmermann has been writing on security and malware subjects for many years and has been working in the security industry for over 10 years. Daniel was educated at the Saarland University in Saarbrücken, Germany and currently lives in New York.

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