SDEN Ransomware - How to remove

SDEN is ransomware — one of the most devastating types of malware. SDEN will encrypt your files (text documents, spreadsheets, movies, songs — almost every popular file format), making them unintelligible. This is, in theory, a reversible process and the criminals are offering to fix the files for a ransom.

SDEN is a Matrix family ransomware. Based on that, we can speculate that shadow copies and restore points are deleted. Shadow copies and restore points could be used to get most of your files back without having to pay the ransom, so them being deleted can make SDEN very dangerous.

How to recognise SDEN?

You will notice that you have lots of files with unrecognisable names with the SDEN extension. These would be your your encrypted files.

[[email protected]].[random caharcters].SDEN

A ransom note called !SDEN_INFO!.rtf is created after the encryption process is done.

Three email addresses are given for contacting the managers of SDEN:

[email protected]
[email protected]
[email protected]

HOW TO RECOVER YOUR FILES?

WE HAVE TO INFORM YOU THAT ALL YOUR FILES WERE ENCRYPTED!

PLEASE BE SURE THAT YOUR FILES ARE NOT BROKEN!
Your files were encrypted with AES-128+RSA-2048 crypto algorithms.
* Please note that there is no way to decrypt your files without unique decryption
key and special software. Your unique decryption key is securely stored on our
server.
* Please note that all the attempts to recover your files by yourself or using third
party tools will result only in irrevocable loss of your data!
* Please note that you can recover files only with your unique decryption key, which
stored on our server.

HOW TO RECOVER FILES?
Please write us to the e-mail, we will send you instruction how to recover your data.
Our main e-mail: [email protected]
Our secondary e-mail: [email protected]
Our secondary e-mail: [email protected]

Please write to our main e-mail. If you will not receive answer in 24 hours, please
write to our secondary e-mails! Please always check SPAM folder!
* Write on English or use professional translator

In subject line write your personal ID: [id]

For your assurance you can attach up to 3 small encrypted files to
your message. We will decrypt and send you decrypted files for free.
* Please note that files must not contain any valuable information and their
total size must be less than 5Mb.

Please don’t worry, we can help you to RESTORE your server to original
state and decrypt all your files quickly and safely!

OUR HELP!
You have to pay for our help in Bitcoin Cryptocurrency.
Immediately after payment we will send you (by e-mail) automatic decryption tool
and your unique decryption key. You just have to start decryption tool on your
server and all files will be automatically decrypted. All original file names will be
restored too.

The ransom note looks just like the one for the PEDANT virus. Cybercriminals don’t develop each cryptovirus from scratch. Instead, they iterate on the same programs. For example, there is a ransomware infection almost exactly the same as this one, but with the files having the MDEN, and the ransom note being called !MDEN_INFO!.rtf.

How does ransomware work?

The encryption

AES is a symmetric encryption algorithm, RSA — asymmetric. This most likely means that they’re using hybrid encryption. The key to decrypt your SDEN files, then, is stored on your computer, but is encrypted itself. The key to decrypt your key is stored on a server controlled by the cybercriminals.

The distribution

Ransomware like SDEN usually uses similar distribution methods to other malware.

Some target individuals:

  • Drive-by downloads: malware can be downloaded by just visiting an infected website, or clicking on a direct download link.
  • Files with macro viruses: some files (usually spread by spam emails) try to entice people into opening them by being disguised as important documents.
  • Peer-to-peer filesharing, where malicious actors share viruses.

Other malware distribution methods might be more targeted at businesses:

  • Ransomware could be downloaded by someone who has hijacked a computer remotely, for example, through Remote Desktop (this is why complex passwords are important).
  • Installed by infected physical media (an infected USB drive left lying around, betting on a someone connecting it to a computer).

sden ransom note

 

Make sure that you keep copies of your important files in separate from your computer storage so that SDEN or another ransomware infection is not totally devastating. Be skeptical of any unfamiliar people sending you emails about receiving invoices, fines, or bills that you did not expect. Scan the files that you downloaded before opening and running them.

How to remove the SDEN virus

Keep in mind that storing file backups either in the Cloud, in another computer, or external memory is advised. Otherwise, the backup will be encrypted by SDEN together with the other files.

If your very important files have been encrypted, you can still save them and hope that a free decryption tool is developed (you can check NoMoreRansom.org). Save the files off your computer before you start removing the SDEN virus.

Scan your system with a professional antivirus program (Spyhunter or another trusted application) and remove the infection. Then you can try the guide below to restore your files without having to pay the ransom.

Automatic Malware removal tools

Download Spyhunter for Malware detection
(Win)

Note: Spyhunter trial provides detection of parasites and assists in their removal for free. limited trial available, Terms of use, Privacy Policy, Uninstall Instructions,

Download Combo Cleaner for Malware detection
(Mac)

Note: Combo Cleaner trial provides detection of parasites and assists in their removal for free. limited trial available, Terms of use, Privacy Policy, Uninstall Instructions, Refund Policy ,


How to recover SDEN Ransomware encrypted files and remove the virus

Step 1. Restore system into last known good state using system restore

1. Reboot your computer to Safe Mode with Command Prompt:


for Windows 7 / Vista/ XP
  • Start Shutdown RestartOK.
  • Press F8 key repeatedly until Advanced Boot Options window appears.
  • Choose Safe Mode with Command Prompt. Windows 7 enter safe mode

for Windows 8 / 10
  • Press Power at Windows login screen. Then press and hold Shift key and click Restart. Windows 8-10 restart to safe mode
  • Choose TroubleshootAdvanced OptionsStartup Settings and click Restart.
  • When it loads, select Enable Safe Mode with Command Prompt from the list of Startup Settings. Windows 8-10 enter safe mode
 

2.Restore System files and settings.

  • When Command Prompt mode loads, enter cd restore and press Enter.
  • Then enter rstrui.exe and press Enter again.CMD commands
  • Click “Next” in the windows that appeared. Restore point img1
  • Select one of the Restore Points that are available before SDEN has infiltrated to your system and then click “Next”. Restore point img2
  • To start System restore click “Yes”. Restore point img3
 

Step 2. Complete removal of SDEN Ransomware

After restoring your system, it is recommended to scan your computer with an anti-malware program, like Spyhunter and remove all malicious files related to SDEN. You can check other tools here.  

Step 3. Restore SDEN Ransomware affected files using Shadow Volume Copies

If you do not use System Restore option on your operating system, there is a chance to use shadow copy snapshots. They store copies of your files that point of time when the system restore snapshot was created. Usually SDEN tries to delete all possible Shadow Volume Copies, so this methods may not work on all computers. However, it may fail to do so. Shadow Volume Copies are only available with Windows XP Service Pack 2, Windows Vista, Windows 7, and Windows 8. There are two ways to retrieve your files via Shadow Volume Copy. You can do it using native Windows Previous Versions or via Shadow Explorer. a) Native Windows Previous Versions Right-click on an encrypted file and select PropertiesPrevious versions tab. Now you will see all available copies of that particular file and the time when it was stored in a Shadow Volume Copy. Choose the version of the file you want to retrieve and click Copy if you want to save it to some directory of your own, or Restore if you want to replace existing, encrypted file. If you want to see the content of file first, just click Open.
Previous version
b) Shadow Explorer It is a program that can be found online for free. You can download either a full or a portable version of Shadow Explorer. Open the program. On the left top corner select the drive where the file you are looking for is a stored. You will see all folders on that drive. To retrieve a whole folder, right-click on it and select “Export”. Then choose where you want it to be stored.
Shadow explorer

Step 4. Use Data Recovery programs to recover SDEN Ransomware encrypted files

There are several data recovery programs that might recover encrypted files as well. This does not work in all cases but you can try this:
  • We suggest using another PC and connect the infected hard drive as slave. It is still possible to do this on infected PC though.
  • Download a data recovery program.
  • Install and scan for recently deleted files. Data Recovery Pro
Note: In many cases it is impossible to restore data files affected by modern ransomware. Thus I recommend using decent cloud backup software as precaution. We recommend checking out Carbonite, BackBlaze, CrashPlan or Mozy Home.
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