Remove Cosanostra Ransomware Virus – Restore PC

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An infection with the dangerous Cosanostra ransomware virus leads to serious security issues. With our removal guide, victims can try to secure their computers and restore encrypted files.

Manual Removal Guide
Files Recovery Approaches
Skip all steps and download anti-malware tool that will safely scan and clean all harmful files it detects on your PC.

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Note for Mac users!
In case that your Mac has been affected by Cosanostra or you suspect that other threats are running on it you can follow detailed instructions on how to detect and remove Mac viruses so you can keep the device clean and secure.

Distribution of Cosanostra Ransomware Virus

The so-called Cosanostra ransomware is a devastating cryptovirus that has been recently released in attack campaigns against computer users worldwide. Threat actors could be utilizing widely used tactics of distribution to infect computer systems.

One of the methods that may be used by the malicious actors behind Cosanostra ransomware includes the coordination of SPAM email messages — they are used to spread the threat by sending out messages that pose as legitimate notifications sent by popular Internet portals or services that the targets may use. The virus files can be either directly attached or linked in the body. They can also be uploaded to fake download sites which are designed to appear like any of the popular Internet portals or vendor download sites. The malicious actors may use similar sounding domain names, certificates and hijacked design and contents to coerce the victims into thinking that they are accessing the legitimate address.

Another way that the threat may spread is through infected payloads — the use of various files that are infected with virus code. A popular example is the malicious document which can take any form: presentations, rich text files, spreadsheets and databases. Once they are opened by the victims a notification message will pop-up asking the target users to enable the built-in scripts. If this is done the virus infection will follow. The other popular technique is the inclusion of the code in application installers. They are malicious copies of legitimate setup files of popular end-user programs that have been modified with the Cosanostra ransomware code.

Ransomware files are also popularly spread by fake user profiles — they can post to community forums or social media accounts. The criminals can utilize both fake or stolen identities to increase the number of infected users.

In certain cases, the criminals may also be distributed via malicious browser plugins — additions to the most popular web browsers that are advertised as useful. The plugins are uploaded to the official repositories and often make use of fake or hijacked user reviews and developer credentials. Once they are installed by the users they will execute their built-in instructions that in many cases leads to the Cosanostra ransomware virus infection in the end.

Impact of Cosanostra Ransomware Virus

Analyses of Cosanostra cryptovirus samples reveal that it belongs to the infamous GarrantyDecrypt ransomware family. Security researchers found out that it acts like a typical data locker ransomware that plagues computer system settings so that it can reach target types of files and encode them with the help of sophisticated cipher algorithm.

Even if Cosanostra ransomware virus does not render your PC inoperable, it applies a lot of modifications that disrupt the security of your system.

The beginning of infection with Cosanostra ransomware begins when its payload is executed on the system. The moment this occurs the threat becomes able to initiate a long sequence of malicious operations that support different stages of the attack. At first, the ransomware creates additional malicious files which are needed for the completion of all following infection stages.

Malicious files could be either created directly on the system or dropped from a remote server. Cosanostra may use the following system folders for their storage – %Roaming% , %Windows% , %AppData% , %Local% , %Temp%

Once it establishes all needed files, the threat starts executing them in a predefined order. This sequence of processes, in turn, results in heavy system settings modifications. Affected could be also registry keys like RUN and RUNONCE stored by the Windows Registry, legitimate system processes and settings of other essential components.

Following system corruption, Cosanostra ransomware activates a built-in encryption module, an action that marks the beginning of the main infection stage – data encryption. Since this module is designed to transform the code of targeted files by utilizing sophisticated cipher algorithm, corrupted files remain unusable until their code is reverted back to its original state.

Encrypted and as a consequence renamed with the extension .cosanostrar could be:

  • Documents
  • Archives
  • Backups
  • Databases
  • Images
  • Videos
  • Music

At the end of the attack, Cosanostra drops a text file named #RECOVERY_FILES#. This file contains a ransom message that loads on the screen. to inform you about its presence and impacts. This ransom message aims to inform you about the presence of Cosanostra on your device, the impacts it has just caused and furthermore attempts to blackmail you into paying hackers a ransom free for files decryption:

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
[email protected] com
And tell us your unique ID

Remember that ransom payment does not guarantee the recovery of .cosanostra files as hackers could send you a broken decryptor or skip contacting you at all. For the sake of your security, you should avoid paying them the requested ransom and attempt to deal with the problem by use of secure methods that won’t steal both your money and data.

Remove Cosanostra Ransomware Virus and Restore PC

Please note that paying the requested ransom fee to cybercriminals does not really solve your problem with Cosanostra cryptovirus. In fact, you only encourage hackers to continue spreading ransomware of this kind. Instead, you must remove the threat immediately, and only then look for optional ways to recover your data.

WARNING! Manual removal of Cosanostra ransomware virus requires being familiar with system files and registries. Removing important data accidentally can lead to permanent system damage. If you don’t feel comfortable with manual instructions, download a powerful anti-malware tool that will scan your system for malware and clean it safely for you.

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Cosanostra Ransomware Virus – Manual Removal Steps

Start the PC in Safe Mode with Network

This will isolate all files and objects created by the ransomware so they will be removed efficiently. The steps below are applicable to all Windows versions.

1. Hit the WIN Key + R

2. A Run window will appear. In it, write msconfig and then press Enter

3. A Configuration box shall appear. In it Choose the tab named Boot

4. Mark Safe Boot option and then go to Network under it to tick it too

5. Apply -> OK

Show Hidden Files

Some ransomware threats are designed to hide their malicious files in the Windows so all files stored on the system should be visible.

1. Open My Computer/This PC

2. Windows 7

    – Click on Organize button
    – Select Folder and search options
    – Select the View tab
    – Go under Hidden files and folders and mark Show hidden files and folders option

3. Windows 8/ 10

    – Open View tab
    – Mark Hidden items option

how to make hidden files visible in Windows 8 10 bestsecuritysearch instructions

4. Click Apply and then OK button

Enter Windows Task Manager and Stop Malicious Processes

1. Hit the following key combination: CTRL+SHIFT+ESC

2. Get over to Processes

3. When you find suspicious process right click on it and select Open File Location

4. Go back to Task Manager and end the malicious process. Right click on it again and choose End Process

5. Next, you should go folder where the malicious file is located and delete it

Repair Windows Registry

1. Again type simultaneously the WIN Key + R key combination

2. In the box, write regedit and hit Enter

3. Type the CTRL+ F and then write the malicious name in the search type field to locate the malicious executable

4. In case you have discovered registry keys and values related to the name, you should delete them, but be careful not to delete legitimate keys

Click for more information about Windows Registry and further repair help

Recover Encrypted Files

WARNING! All files and objects associated with Cosanostra ransomware virus should be removed from the infected PC before any data recovery attempts. Otherwise the virus may encrypt restored files. Furthermore, a backup of all encrypted files stored on external media is highly recommendable.

DOWNLOAD SpyHunter Anti-Malware Tool

 
SpyHunter is a Windows application designed to scan for, identify, remove and block malware, potentially unwanted programs (PUPs) and other objects. By purchasing the full version, you will be able to remove detected malware instantly. Additional information about SpyHunter / Help to uninstall SpyHunter

1. Use present backups

2. Use professional data recovery software

Stellar Phoenix Data Recovery – a specialist tool that can restore partitions, data, documents, photos, and 300 more file types lost during various types of incidents and corruption.

3. Using System Restore Point

    – Hit WIN Key
    – Select “Open System Restore” and follow the steps

restore-files-using-windows-system-restore-point

4. Restore your personal files using File History

    – Hit WIN Key
    – Type restore your files in the search box
    – Select Restore your files with File History
    – Choose a folder or type the name of the file in the search bar
    – Hit the “Restore” button

Preventive Security Measures

  • Enable and properly configure your Firewall.
  • Install and maintain reliable anti-malware software.
  • Secure your web browser.
  • Check regularly for available software updates and apply them.
  • Disable macros in Office documents.
  • Use strong passwords.
  • Don’t open attachments or click on links unless you’re certain they’re safe.
  • Backup regularly your data.
  • How disturbing is this problem?

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    Gergana Ivanova

    Author : Gergana Ivanova

    Gergana Ivanova is computer security enthusiast who enjoys presenting the latest issues related to cyber security.

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