Remove Cosd Ransomware (.cosd Files)

This post is all about the hazardous crypto-virus called Cosd, Removal Guide, File Recovery options, Computer Protection, and Tutorial Video to get rid of the threat.

Cosd ransomware virus is part of STOP/DJVU family that may lock your valuable files with both AES and RSA 1024-bit encryption algorithm. The same type of methodology used in older variants to restrict victims from using or opening their own data. A .cosd extension is to be appended on infected files as additional technique to disallow its operation. As an example, familypic.jpg will turn into familypic.jpg.cosd after it was fully encrypted by the virus.

More about Cosd Ransomware

Cosd authors are currently utilizing several ways to reach your computer. A Trojan known to be dropping payload is meant to contaminate the computer and initiate a malicious code to further infect the system with Cosd ransomware. Other widely used internet services that are productively spreading Cosd ransomware include links from social media, spam email campaigns, and file-sharing networks. Through these tactics, people behind Cosd ransomware ought to use deceitful techniques to be able to influence victims to click a link or download the attractive program, which will actually trigger the contamination. he same approach is used in older versions of this virus such as Plam, Pola, Wbxd, and many more.

Screenshot of Cosd encrypted files

Once fully operational on the infected computer, Cosd ransomware searches the hard drive and attached storage devices for target files that are usually in the format of .doc, .xls, .ppt, .pdf, .jpg, .png, .dwg, .zip, .rar, .mp4, .psd, and many more. After that, it proceeds with encryption process to all selected files followed by modification of their extension. Following the file-locking development is the notification course where Cosd ransomware confirms the completion of the encryption process through the generated _readme.txt file.

The ransom note specifically describes the complexity of recovering all .cosd files. Along with this disturbing declaration is a suggestion to contact malware authors if victim’s desire to restore the data to previous standard format. On this page is an excerpt from the ransom note and screenshot image of encrypted files.

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…
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…

Backup your files

One important step before proceeding with the procedures below is to backup your files. Ransomware are not the same. Each has its unique sets of payloads aside from encrypting the files with complex method. Others tend to delete the infected files after certain period, while others keep them concealed on hidden places. In addition, ransomware decryption tools are not guaranteed to be perfect, there are instances that files suffer from damages during the decryption process.

So, create a backup copy of your entire Cosd encrypted files right now.

Cosd Ransomware Removal Guide

First thing to do is remove the Cosd virus before attempting the decryption. Remember that as long as the ransomware is active, it will repeatedly encrypt the files on the compromised computer.

Infection of Cosd ransom virus is dangerous to the system because it can inject files that runs each time Windows starts. To prevent the malicious files from loading, Windows operating system must run with minimal process and it can be done through SafeMode With Networking.

Stage 1 : Temporarily Disable System Restore on Windows OS

Because Cosd and relevant virus is capable of reinstating itself by exploiting the System Restore of Windows, we suggests that you temporary disable System Restore while executing the steps. This option is also helpful to effectively run a full scan on the computer.

Do not forget to enable back System Restore after completing the removal of Cosd ransomware. This feature is vital in reinstating the operating system to previous normal working condition in case of problems or conflicts occurs.

Stage 2 : Start Windows in Safe Mode With Networking

Windows 10 Guide

1. Click on Windows logo and select Power icon when options pop-ups.
2. Select Restart from the options while pressing Shift key on the keyboard.
3. Choose an Option window will appear, select the Troubleshoot button.
4. On next window, please choose Advanced Option.
5. On Advanced Option window, click on Startup Settings and then, click Restart button to reboot the computer.
6. When Windows boot on Startup Settings, press function key F5 or number 5 on keyboard.

A simpler alternative for Windows 10 users is to scan the computer with Microsoft Defender Offline. This will run a virus scan in the recovery environment.

Windows 8 Guide

1. Click Windows Start icon at the lower left section of the screen.
2. Open Search window and type Advanced in the field. It will open General PC Settings.
3. Click on Advanced Startup and then, click on Restart Now button.
4. Once the computer starts in Advanced Startup option menu, select Troubleshoot.
5. Next, click on Advanced Options to reveal the next section.
6. Click Startup settings and then, click Restart button to boot the PC in Startup Settings.
7. Use function key F5 or number key 5 to Enable Safe Mode with Networking.

Stage 3 : Scan the Computer with Sophos Antivirus

Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Cosd virus. Aside from our suggested tool, you may also run your own security program.

To remove Cosd automatically, scanning the computer with this efficient anti-malware tool is suggested. This scanner does not just uncover known threats like viruses or malware, it is also effective in discovering hazardous ransomware like Cosd.

1. Download Sophos Virus Removal Tool from the link below. Save the file on your computer where you can easily access it.

2. Once the download completes, browse the location of the file. Double-click to run the program and begin the install process.

Screnshot of Sophos Installer

3. On first windows of installation wizard, click Next to continue. Then, it will display the program’s License Agreement. You need to Accept the terms in order to proceed. If Windows prompts for User Account Control, please click Yes to proceed.

Screenshot of Sophos EULA Page

4. On succeeding windows, click Next or Continue to carry on with the installation. After completing the installation process, Launch Sophos Virus Removal Tool.

5. Internet connection is required when running this virus scanner in order to download important updates. Make sure that everything is up-to-date to effectively remove Cosd ransomware and other relevant viruses.

6. Click the Start Scanning button to inspect the computer. This will check the system for presence of malicious objects, malware, and viruses. The tool reveals items that were found linked to Cosd and other suspicious entities. Be sure to remove all identified threats.

Screenshot of Sophos Virus Scan

The above procedures should have totally eliminated Cosd ransomware. However, if you found that there are still remnants of the virus, please proceed to succeeding procedures below.

Stage 4 : Double-check with Microsoft's Malicious Software Removal Tool

1. Download the free scanner called Malicious Software Removal Tool.

Download MSRT

2. The tool automatically checks the operating system and suggest appropriate download version. Click on Download button to begin. Save the file to a convenient location, preferably on Desktop.

3. After downloading the file, Windows will prompt that download has completed. Click Run to start scanning for Cosd ransomware. Another option is to browse the location folder and double click on the file to run.

MSRT Icon

4. The tool will display Welcome screen, click Next. Please note the message "This tool is not a replacement for an antivirus product." You must understand that this program is made specifically to find and remove malware, viruses, Trojans, and other harmful elements on the computer. It was not designed to protect the computer.

MSRT Welcome

5. Next, you will see Scan Type. Please choose Full Scan to ensure that all Cosd ransom virus entities and other harmful files left on the computer will be found and removed. For advanced computer user, you can opt for Customized Scan, if there are other drives or folders you wanted to include in this scan.

MSRT Scan

6. Full scan may take a while, please wait for Malicious Software Removal Tool to complete the tasks. However, you may cancel the scan anytime by clicking on the Cancel button.

MSRT Scan

7. After scanning, the tool will reveal all identified threats. There may be other threats that our first scan fails to detect. Please remove/delete all detected items.

8. When removal procedure is complete, you may now close Malicious Software Removal Tool. We hope that Cosd ransomware have been completely deleted from the computer. Please restart Windows to proceed with the normal operation.

Recover Files from Cosd Ransomware Infection

On this section, we will provide ways to decrypt files infected with Cosd ransomware. Aside from dedicated decryption software and common tools, other options for file recovery are provided. As much as we can, we will update this area whenever there is new and more suitable decryption tool was made available.

Decrypting Cosd infected files with Emsisoft Tools

This service from Emsisoft is helpful in unlocking encrypted files without paying the ransom. It gives three ways to detect the ransomware and provide suitable recovery method:

Upload ransom note – This is usually the .txt or .hta files that was generated by Cosd ransomware.

Upload the encrypted file – The actual encrypted file. Choose the one that is less than 8MB in size.

Contact information – Enter the email address or any links provided as it appears in the ransom note of Cosd virus.

Emsisoft Tools

After submitting any of the appropriate data, Emsisoft will attempt to identify the ransomware and provide keys if there are available.

Option 1: Windows Previous Version Tool

Windows Vista and Windows 7 have a feature called Previous Versions. However, this tool is only usable if restore point was made prior to ransomware infection. To use this tool as "recovery option" for files encypted by Cosd virus, please follow these steps:

1. Open My Computer or Windows Explorer.

2. Right-click on the affected files or folders. From the drop-down list, please click on Restore previous versions.

3. New window will open display all backup copy of files and folders you wanted to recover. Choose the appropriate file and click on Open, Copy, or Restore. Restoring selected files overwrites the current locked files on the computer. The tool is not actually recovering files encrypted by Cosd. Instead, it restores files from backup copy.

Option 2: Use ShadowExplorer to restore files encrypted by Cosd Ransomware

Just like Previous Version tool, ShadowExplorer is taking advantage of shadow copy created by Windows. This tool allows you to retrieve older version of files before it was encrypted by Cosd ransomware.

1. Download ShadowExplorer from the official web site.

2. Install the program with the default settings.

3. The program should run automatically after installation. If not, double-click on ShadowExplorer icon.

4. You can see the drop-down list on top of the console. Please select proper drive and the most recent point-in-time shadow copies of files you wish to restore prior to Cosd ransomware infection.

shadow3

5. Right-click on the Drive, Folder, or File you wish to restore and click Export...

6. Lastly, ShadowExplorer will prompt for location where you want to save the copy of recovered files.

How to protect the computer from Cosd ransomware?

After the removal of the ransomware, it is important to prevent similar incident from happening again. In order to protect the computer effectively, computer user must know how Cosd ransomware was able to infect the computer. To minimize the possible infection, staying away from the common sources of this virus is crucial.

How Cosd ransomware can infect your computer?

The method of infecting the computers was found to be similar as other common viruses. Though, ransomware like Cosd is seen to have efficient deployment via spam email messages, web injectors, malicious software installers, misleading online advertisements, and through another virus infection.

Once the virus is executed, it immediately infects the system. Then, Cosd ransomware communicates to remote server so that unique key can be generated for the specific computer. After acquiring the key, it starts to decrypt target files using a complex method that is almost unbreakable. On the last stage of the attack, Cosd ransomware demands for ransom money as payment for the decryption tool. To further understand the attack scheme, we have included an infographic below.

Infographic image of ransomware attack stages
You can print, download, or share the infographic by clicking the image.

Securing the computer against ransomware attack

Do a Regular File Back-up - Always backup your data on a separate storage devices such as external hard drives, optical discs, or online backup services.

Keep Your Software Updated - Make sure that you have the latest software updates especially on the operating system. Recent updates often contain vital security patches to help protect the computer against all forms of threats.

Install a Security Program - Protect the computer with effective anti-virus application using efficient real-time scanning. Regularly run a complete scan to check the computer for presence of malware.

Protect your files with Controlled Folder Access (Windows 10)

For Windows 10 users, aside from protecting the computer using anti-virus or anti-malware programs, one way to protect against ransomware attack is by using Controlled Folder Access. This feature of Windows Defender Security Center may not prevent the Cosd ransomware infection, but it can protect the folder and files in general. Follow the steps to enable Controlled Folder Access in Windows 10.

1. Go to Windows 10 Taskbar and search for Windows Defender Security Center.

2. Open Windows Defender Security Center and click on Virus & Threat Protection icon.

Virus and Threat Protection

3. On next window, please click on Ransomware Protection.

4. Under Controlled Folder Access section, switch the slider to On. That will enable the feature and protect the folder against Cosd or any type of ransomware.

Controlled Folder Access

5. Click on Protected Folderslink to include additional folders. Make sure that folders where important files are located should be included in the list.

Add Protected Folder

Troubleshooting Guide

Certain programs maybe blocked by Controlled Folder Access feature. To fix the issue, simply have the specific program to be white listed.

1. Under Protected Folders, click Allow an app through controlled folder access.

2. Next, click the Add an allowed app and include the target executable file.

This Controlled Folder Access feature is one way to protect files against Cosd. Other important things to do in keeping files safe against ransomware is through early prevention like keeping programs updated, install an efficient security program, an do regular file backup on a separate media drive.

Tutorial video to remove Cosd

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