Sherminator (Mr.Dec) Ransomware - How to remove

Sherminator is a relatively new piece of malware that has started terrorizing people by locking their files and demanding money. It uses an unusual file extension for the locked files — [ID]xxxxxxxxxxxxxxxx[ID], but instead of ‘x’, you have random letters, numbers, and other symbols.

This program was noticed a by cybersecurity researcher a few days ago, September of 2019, as a copy of another ransomware from June. That one also used the [ID]…[ID] type of extension for the locked files.

Other examples of ransomware include Kokoklock, HildaCrypt, Tanos — all file-locking malware that uses cryptography to make the files securely broken. Encryption is reversible, but only if you know the encryption algorithm and the decryption key — this is information that’s only known to the extortionists.

Sherminator was named after one of the email addresses given by the ransom note (Decoder.hta). If you open that note, [email protected] and [email protected] are the addresses that the victims of this ransomware are told to contact if they want to pay the ransom for their files.

Don’t rush to do that, though — maybe there are other ways to get your files back without having to contact the criminals. Holding victims’ data for ransom — ransomware — might be one of the worst types of malware, it’s certainly a crime, and the criminals responsible for Sherminator certainly shouldn’t be trusted.

Sherminator memo:

Symptoms	Files marked with the [ID][random][ID] extension Files can’t be opened Decoder.hta file left behind with a ransom note “[email protected]” and “[email protected]” are in the ransom note
Sources	Remote Desktop hacked Malicious email spam Pirated files Malicious ads
Remove Sherminator	Automatic scan with an anti-malware tool (SpyHunter)
Restore the files	Restore from backups Use system restore Use shadow volume copies Return lost data using data recovery software

Sherminator details

Here’s the ransom note that Sherminator leaves after encoding the files:

You are unlucky! The terrible virus has captured your files! For decoding please contact by email
[email protected]
or
[email protected]
Your
[ID]
1. In the subject title write your ID
2. Attach 1-2 infected files that do not contain important information (less than 2 mb) are required to generate the decoder and restore the test file.
ATTENTION!
Hurry up! Time is limited!
Do not contact third parties for help, this may lead to the fact that you will be deceived and you will not receive your decoder.
REMEMBER – only we have a tool to get your files back!

If this note by Sherminator locked your screen and you can’t get past it, check this guide on how to kill malicious processes.

Anyway, the note implies that your time is limited but that’s likely not true — extortionists usually say that to stop people from looking for alternatives. The criminals also offer to decrypt for free a couple of small files to prove that they can, however, there have been reports about Mr.Dec’s extortionists sending a bogus decrypter in exchange for the ransom. No surprise — criminals can’t be trusted.

There are unique extensions given by Sherminator to each encrypted file — [ID][random][ID]. Removing the extension shouldn’t do anything for the files, they’ll still be broken, but make a backup of the files and then try. It’s possible that some types of files weren’t encrypted properly, such as audio files or big text files.

Other than that, it’s probably impossible to decrypt the files, at least right now. Sometimes ransomware experts find a way to break Sherminator’s encryption, usually thanks to flaws in the ransomware code. However, Mr.Dec hasn’t been cracked yet, and might never be. Luckily, there are a few other things to try.

How ransomware spreads

In general, the two mains ways for ransomware to spread are RDP and malicious spam.

If you use Remote Desktop to allow access to your computer, if it’s poorly secured, then criminals are going to take advantage of it inevitably to plant malware and steal information. Make sure to secure your RDP before that happens (use VPN, limit IPs that can connect, use complicated passwords, limit users’ privileges, and so on).

Malicious spam is when infected files and links are sent in email letters. These are usually not targeted and are general, so they lack any details and just try to make the recipient curious enough that they would download and open the attachment. An example of a commonly used subject is an urgent invoice or bill. Sherminator could use email spam, but other infections can use a similar tactic with social media messages.

Other ways include ransomware being hidden in pirated files, in cracks, being injected by an infected website.

How to recover Sherminator files and remove the malware

The coders of file-encrypting malware try what they can to prevent victims of their infection from getting their files back. However, this doesn’t always work — even ransomware can have bugs. So, check the section below which describes a few ways that data lost to ransomware can possibly be restored.

This is unnecessary if you already have copies of your files. Backups are the best defense against Sherminator and any other file-encrypting ransomware.

But before that, it’s important to make sure that the Sherminator virus is gone from your computer (and any other malware that could have been installed with it). One way to do that is to simply scan your computer with an anti-malware program, such as SpyHunter. The Sherminator infection is detected by an rising number of anti-malware tools, so if you use up-to-date and professional security software, you should be able to find Sherminator if it’s still on your computer.

Automatic Malware removal tools

How to recover Sherminator (Mr.Dec) 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 → Restart → OK.
• Press F8 key repeatedly until Advanced Boot Options window appears.
• Choose Safe Mode with Command Prompt.

for Windows 8 / 10

• Press Power at Windows login screen. Then press and hold Shift key and click Restart.
• Choose Troubleshoot → Advanced Options → Startup Settings and click Restart.
• When it loads, select Enable Safe Mode with Command Prompt from the list of Startup Settings.

 

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.
• Click “Next” in the windows that appeared.
• Select one of the Restore Points that are available before Sherminator has infiltrated to your system and then click “Next”.
• To start System restore click “Yes”.

 

Step 2. Complete removal of Sherminator (Mr.Dec) 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 Sherminator. You can check other tools here.  

Step 3. Restore Sherminator (Mr.Dec) 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 Sherminator 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 Properties → Previous 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.

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.

Step 4. Use Data Recovery programs to recover Sherminator (Mr.Dec) 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.

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.