Sigrun ransomware (virus) - 2021 update

Sigrun virus Removal Guide

What is Sigrun ransomware?

Sigrun is a file-locking ransomware that demands ransom in Dash or Bitcoin for file decryption

Sigrun ransomware

Sigrun is a ransomware virus that was discovered by security researchers in the middle of May 2018.[1] Malware enters machine unnoticed, executes its payload and then locks up all audio, video, picture, text, database and other personal files. It uses complicated cryptography to add a .sigrun file extension, making all data unusable.

The virus drops ransom note into each of the “RESTORE-SIGRUN.txt” into each of the infected folders and also opens up a browser tab with the same message in .html format. Users are asked to contact hackers via sigrun_decryptor@protonmail.ch in order to get their files back. Victims are asked to pay up to $2,500 in Dash or Bitcoin cryptocurrency, although Russians can get a decryptor for free.

SUMMARY
Name Sigrun
Type Ransomware
File extension .sigrun
Ransom notes RESTORE-SIGRUN.txt and RESTORE-SIGRUN.html
Contact email sigrun_decryptor@protonmail.ch
Distribution Spam emails, fake downloads, repacked software installers, etc.
Symtoms Unusable files
Elimination Use reputable security software SpyHunter 5Combo Cleaner or Malwarebytes
Repair System functions require additional help from tools like ReimageIntego

It is interesting how ransomware authors are going for Norse mythology as Sigrun means “victory rune” and is a valkyrie – a mythological angel-like creature. Nevertheless, the authors of the ransomware are of Russian origin due to the fact that they try to avoid infecting Russian individuals.

The file-locking virus spreads via contaminated attachments in spam emails. Users who open the .txt, .pdf, .doc, .zip, or other affixed files instantaneously download malware into their computers. It is then ready to start its malicious activities.

First, the crypto-virus modifies certain system files (including registry entries) to acquire boot persistence. This way, it can start up every time Windows is launched. Next, it initiates a full system scan to find files to lock up. As soon it is complete, Sigrun malware encrypts data and executes the ransom notes to inform the user about the situation.

Various file types are targeted by the virus, including .txt, .doc, .html, .xlsx, .dat, .mp3, .jpg. .gif and similar. For example, the encoded file would look like this: picture.jpg.sigrun. The strong encryption algorithm is used for file encryption, and only a key can unlock them. These decryptors are usually stored on a remote server and are only accessible to hackers. Nevertheless, users should ignore the key – remove the ransomware first and then proceed with file recovery.

There are several files that the virus does not targets, including:

  • .sigrun
  • .admin
  • .dll
  • .sys
  • .exe
  • .ico
  • .key, etc.

Users are urged to contact criminals via the sigrun_decryptor@protonmail.ch address. The size of ransom is unknown, and it seems like hackers communicate with the victim before agreeing on the size of the payment. It is typically demanded in Bitcoin or another popular cryptocurrency, like Monero or Ethereum. Victims are also offered the proof that decryption is possible – they can send authors three files which they would decode for free.

Sigrun malwareThe ransomware is a file-encrypting virus that locks up all files and demands ransom for its release.

The note states the following:

Dear user, all your important files have been encrypted! Don't worry! Your files still can be restored by us! In order to restore it you need to contact with us via e-mail.

sigrun_decryptor@protonmail.ch

As a proof we will decrypt 3 files for free! Please, attach this to your message:

As we already mentioned, cybercriminals should be ignored as they often do not provide the offered key. Besides, even if they do, they will know that you are susceptible to the demands and might contaminate your machine again in the future. Instead, reboot your PC in Safe Mode with Networking and take care of Sigrun removal. Security experts[2] suggest using ReimageIntego or SpyHunter 5Combo Cleaner for that task.

If you have a backup ready – you are lucky, as you can recover all your files without problems, as long as they are stored on a remote server and not connected to the contaminated machine. If you are not that prepared and didn't use data backup, you might be in a bit of trouble. However, you can always try third-party tools that may help you with file recovery.

Hackers help Russian victims for free

Russian cybercriminals are known to avoid infecting Russian-speaking individuals (including former USSR countries), as they are cautious of the authorities, who could target them if locals were involved.

When Sigrun is first executed, it checks for the keyboards layouts installed – “HKEY_CURRENT_USER\Keyboard Layout\Preload.” Once the virus finds the Russian layout, it does not encrypt files and merely deletes itself. However, not all former USSR countries use the Russian layout; therefore, those individuals can still get infected. Hackers also mentioned that they added a Ukrainian layout to the list of exceptions.

While authors of Sigrun virus ask for as much as $2,500 in Dash or Bitcoin for file decryption, all Russian-speaking users have to do is email culprits and they offer their help for free.

Sigrun decryption for free

Avoid deadly ransomware viruses by deleting spam emails

The best practice is not to contaminate your machine with viruses in the first place. Of course, there will never be a guarantee as malware authors continually modify their code to improve avoidance and develop their malicious software distribution methods. However, there is something you can do. You can be more careful and attentive while browsing the internet.

First of all, we suggest using strong passwords for each of your accounts and change them regularly. Note that unprotected RDP configuration or weak passwords might be an easy way for hackers to infiltrate your machine with malware.

Next, you should not open spam emails carelessly. Malicious attachments often hide inside these emails, as well as cleverly-disguised hyperlinks may lead you to malicious payload execution.

Therefore, if in doubt, make sure you delete the message even without looking at it. Beware that some criminals have decent social engineering skills[3] and are great at luring people with perfectly constructed phishing emails.

Finally, avoid suspicious websites, especially cracked software and other file-sharing sites. Additionally, do not click on questionable ads as they might lead you to malware-ridden sites.

Sigrun virus elimination procedure

Remember, you have to remove Sigrun ransomware before you proceed with file recovery. Otherwise, your data will be contaminated and locked up again. If you have remote storage with a backup ready, do not connect it to your machine before you are sure that the virus is exterminated.

Malware can be eliminated using anti-malware tools that have the power to find the pieces of ransomware and other payload pieces. You need tools like SpyHunter 5Combo Cleaner or Malwarebytes to fully eliminate the infection. Otherwise, you risk getting files affected again.

Ransomware viruses are serious threats and use sophisticated code. Thus, do not even try manual Sigrun removal as you will fail. Only trained professionals can execute that task. Instead, employ reputable security software, enter Safe Mode with Networking, and perform a full system scan. If you did not have a backup, check out the alternative file restoration methods below.

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What to do if failed?
If you failed to fix virus damage using Reimage Intego, submit a question to our support team and provide as much details as possible.
Reimage Intego has a free limited scanner. Reimage Intego offers more through scan when you purchase its full version. When free scanner detects issues, you can fix them using free manual repairs or you can decide to purchase the full version in order to fix them automatically.
Alternative Software
Different software has a different purpose. If you didn’t succeed in fixing corrupted files with Reimage, try running SpyHunter 5.
Alternative Software
Different software has a different purpose. If you didn’t succeed in fixing corrupted files with Intego, try running Combo Cleaner.

Getting rid of Sigrun virus. Follow these steps

Isolate the infected computer

Some ransomware strains aim to infect not only one computer but hijack the entire network. As soon as one of the machines is infected, malware can spread via network and encrypt files everywhere else, including Network Attached Storage (NAS) devices. If your computer is connected to a network, it is important to isolate it to prevent re-infection after ransomware removal is complete.

The easiest way to disconnect a PC from everything is simply to plug out the ethernet cable. However, in the corporate environment, this might be extremely difficult to do (also would take a long time). The method below will disconnect from all the networks, including local and the internet, isolating each of the machines involved.

  • Type in Control Panel in Windows search and press Enter
  • Go to Network and Internet Network and internet
  • Click Network and Sharing Center Network and internet 2
  • On the left, pick Change adapter settings Network and internet 3
  • Right-click on your connection (for example, Ethernet), and select Disable Network and internet 4
  • Confirm with Yes.

If you are using some type of cloud storage you are connected to, you should disconnect from it immediately. It is also advisable to disconnect all the external devices, such as USB flash sticks, external HDDs, etc. Once the malware elimination process is finished, you can connect your computers to the network and internet, as explained above, but by pressing Enable instead.

Scan your system with anti-malware

If you are a victim of ransomware, you should employ anti-malware software for its removal. Some ransomware can self-destruct after the file encryption process is finished. Even in such cases, malware might leave various data-stealing modules or could operate in conjunction with other malicious programs on your device. 

SpyHunter 5Combo Cleaner or Malwarebytes can detect and eliminate all ransomware-related files, additional modules, along with other viruses that could be hiding on your system. The security software is really easy to use and does not require any prior IT knowledge to succeed in the malware removal process.

Repair damaged system components

Once a computer is infected with malware, its system is changed to operate differently. For example, an infection can alter the Windows registry database, damage vital bootup and other sections, delete or corrupt DLL files, etc. Once a system file is damaged by malware, antivirus software is not capable of doing anything about it, leaving it just the way it is. Consequently, users might experience performance, stability, and usability issues, to the point where a full Windows reinstall is required.

Therefore, we highly recommend using a one-of-a-kind, patented technology of ReimageIntego repair. Not only can it fix virus damage after the infection, but it is also capable of removing malware that has already broken into the system thanks to several engines used by the program. Besides, the application is also capable of fixing various Windows-related issues that are not caused by malware infections, for example, Blue Screen errors, freezes, registry errors, damaged DLLs, etc.

  • Download the application by clicking on the link above
  • Click on the ReimageRepair.exe
    Reimage download
  • If User Account Control (UAC) shows up, select Yes
  • Press Install and wait till the program finishes the installation process Reimage installation
  • The analysis of your machine will begin immediately Reimage scan
  • Once complete, check the results – they will be listed in the Summary
  • You can now click on each of the issues and fix them manually
  • If you see many problems that you find difficult to fix, we recommend you purchase the license and fix them automatically. Reimage results

By employing ReimageIntego, you would not have to worry about future computer issues, as most of them could be fixed quickly by performing a full system scan at any time. Most importantly, you could avoid the tedious process of Windows reinstallation in case things go very wrong due to one reason or another.

Restore Windows "hosts" file to its original state

Some ransomware might modify Windows hosts file in order to prevent users from accessing certain websites online. For example, Djvu ransomware variants add dozens of entries containing URLs of security-related websites, such as 2-spyware.com. Each of the entries means that users will not be able to access the listed web addresses and will receive an error instead.

Here's an example of “hosts” file entries that were injected by ransomware:

Hosts file

In order to restore your ability to access all websites without restrictions, you should either delete the file (Windows will automatically recreate it) or remove all the malware-created entries. If you have never touched the “hosts” file before, you should simply delete it by marking it and pressing Shift + Del on your keyboard. For that, navigate to the following location:

C:\\Windows\\System32\\drivers\\etc\\

Delete Windows "hosts" file

Restore files using data recovery software

Since many users do not prepare proper data backups prior to being attacked by ransomware, they might often lose access to their files permanently. Paying criminals is also very risky, as they might not fulfill the promises and never send back the required decryption tool.

While this might sound terrible, not all is lost – data recovery software might be able to help you in some situations (it highly depends on the encryption algorithm used, whether ransomware managed to complete the programmed tasks, etc.). Since there are thousands of different ransomware strains, it is immediately impossible to tell whether third-party software will work for you.

Therefore, we suggest trying regardless of which ransomware attacked your computer. Before you begin, several pointers are important while dealing with this situation:

  • Since the encrypted data on your computer might permanently be damaged by security or data recovery software, you should first make backups of it – use a USB flash drive or another storage.
  • Only attempt to recover your files using this method after you perform a scan with anti-malware software.

Install data recovery software

  1. Download Data Recovery Pro.
  2. Double-click the installer to launch it.
    Launch installer
  3. Follow on-screen instructions to install the software. Install program
  4. As soon as you press Finish, you can use the app.
  5. Select Everything or pick individual folders where you want the files to be recovered from. Select what to recover
  6. Press Next.
  7. At the bottom, enable Deep scan and pick which Disks you want to be scanned. Select Deep scan
  8. Press Scan and wait till it is complete. Scan
  9. You can now pick which folders/files to recover – don't forget you also have the option to search by the file name!
  10. Press Recover to retrieve your files. Recover files

Find a working decryptor for your files

File encryption is a process that is similar to applying a password to a particular file or folder. However, from a technical point of view, encryption is fundamentally different due to its complexity. By using encryption, threat actors use a unique set of alphanumeric characters as a password that can not easily be deciphered if the process is performed correctly.

There are several algorithms that can be used to lock data (whether for good or bad reasons); for example, AES uses the symmetric method of encryption, meaning that the key used to lock and unlock files is the same. Unfortunately, it is only accessible to the attackers who hold it on a remote server – they ask for a payment in exchange for it. This simple principle is what allows ransomware authors to prosper in this illegal business.

While many high-profile ransomware strains such as Djvu or Dharma use immaculate encryption methods, there are plenty of failures that can be observed within the code of some novice malware developers. For example, the keys could be stored locally, which would allow users to regain access to their files without paying. In some cases, ransomware does not even encrypt files due to bugs, although victims might believe the opposite due to the ransom note that shows up right after the infection and data encryption is completed.

Therefore, regardless of which crypto-malware affects your files, you should try to find the relevant decryptor if such exists. Security researchers are in a constant battle against cybercriminals. In some cases, they manage to create a working decryption tool that would allow victims to recover files for free.

Once you have identified which ransomware you are affected by, you should check the following links for a decryptor:

No More Ransom Project

If you can't find a decryptor that works for you, you should try the alternative methods we list below. Additionally, it is worth mentioning that it sometimes takes years for a working decryption tool to be developed, so there are always hopes for the future.

Create data backups to avoid file loss in the future

One of the many countermeasures for home users against ransomware is data backups. Even if your Windows get corrupted, you can reinstall everything from scratch and retrieve files from backups with minimal losses overall. Most importantly, you would not have to pay cybercriminals and risk your money as well.

Therefore, if you have already dealt with a ransomware attack, we strongly advise you to prepare backups for future use. There are two options available to you:

  • Backup on a physical external drive, such as a USB flash drive or external HDD.
  • Use cloud storage services.

The first method is not that convenient, however, as backups need to constantly be updated manually – although it is very reliable. Therefore, we highly advise choosing cloud storage instead – it is easy to set up and efficient to sustain. The problem with it is that storage space is limited unless you want to pay for the subscription.

Using Microsoft OneDrive

OneDrive is a built-in tool that comes with every modern Windows version. By default, you get 5 GB of storage that you can use for free. You can increase that storage space, but for a price. Here's how to setup backups for OneDrive:

  1. Click on the OneDrive icon within your system tray.
  2. Select Help & Settings > Settings.
    Go to OneDrive settings
  3. If you don't see your email under the Account tab, you should click Add an account and proceed with the on-screen instructions to set yourself up.
    Add OneDrive account
  4. Once done, move to the Backup tab and click Manage backup.
    Manage backup
  5. Select Desktop, Documents, and Pictures, or a combination of whichever folders you want to backup.
  6. Press Start backup.
    Pick which folders to sync

After this, all the files that are imported into the above-mentioned folders will be automatically backed for you. If you want to add other folders or files, you have to do that manually. For that, open File Explorer by pressing Win + E on your keyboard, and then click on the OneDrive icon. You should drag and drop folders you want to backup (or you can use Copy/Paste as well).

Using Google Drive

Google Drive is another great solution for free backups. The good news is that you get as much as 15GB for free by choosing this storage. There are also paid versions available, with significantly more storage to choose from.

You can access Google Drive via the web browser or use a desktop app you can download on the official website. If you want your files to be synced automatically, you will have to download the app, however.

  1. Download the Google Drive app installer and click on it.
    Install Google Drive app
  2. Wait a few seconds for it to be installed. Complete installation
  3. Now click the arrow within your system tray – you should see Google Drive icon there, click it once.
    Google Drive Sign in
  4. Click Get Started. Backup and sync
  5. Enter all the required information – your email/phone, and password. Enter email/phone
  6. Now pick what you want to sync and backup. You can click on Choose Folder to add additional folders to the list.
  7. Once done, pick Next. Choose what to sync
  8. Now you can select to sync items to be visible on your computer.
  9. Finally, press Start and wait till the sync is complete. Your files are now being backed up.

Manual removal using Safe Mode

Important! →
Manual removal guide might be too complicated for regular computer users. It requires advanced IT knowledge to be performed correctly (if vital system files are removed or damaged, it might result in full Windows compromise), and it also might take hours to complete. Therefore, we highly advise using the automatic method provided above instead.

Step 1. Access Safe Mode with Networking

Manual malware removal should be best performed in the Safe Mode environment. 

Windows 7 / Vista / XP
  1. Click Start > Shutdown > Restart > OK.
  2. When your computer becomes active, start pressing F8 button (if that does not work, try F2, F12, Del, etc. – it all depends on your motherboard model) multiple times until you see the Advanced Boot Options window.
  3. Select Safe Mode with Networking from the list. Windows 7/XP
Windows 10 / Windows 8
  1. Right-click on Start button and select Settings.
    Settings
  2. Scroll down to pick Update & Security.
    Update and security
  3. On the left side of the window, pick Recovery.
  4. Now scroll down to find Advanced Startup section.
  5. Click Restart now.
    Reboot
  6. Select Troubleshoot. Choose an option
  7. Go to Advanced options. Advanced options
  8. Select Startup Settings. Startup settings
  9. Press Restart.
  10. Now press 5 or click 5) Enable Safe Mode with Networking. Enable safe mode

Step 2. Shut down suspicious processes

Windows Task Manager is a useful tool that shows all the processes running in the background. If malware is running a process, you need to shut it down:

  1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
  2. Click on More details.
    Open task manager
  3. Scroll down to Background processes section, and look for anything suspicious.
  4. Right-click and select Open file location.
    Open file location
  5. Go back to the process, right-click and pick End Task.
    End task
  6. Delete the contents of the malicious folder.

Step 3. Check program Startup

  1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
  2. Go to Startup tab.
  3. Right-click on the suspicious program and pick Disable.
    Startup

Step 4. Delete virus files

Malware-related files can be found in various places within your computer. Here are instructions that could help you find them:

  1. Type in Disk Cleanup in Windows search and press Enter.
    Disk cleanup
  2. Select the drive you want to clean (C: is your main drive by default and is likely to be the one that has malicious files in).
  3. Scroll through the Files to delete list and select the following:

    Temporary Internet Files
    Downloads
    Recycle Bin
    Temporary files

  4. Pick Clean up system files.
    Delete temp files
  5. You can also look for other malicious files hidden in the following folders (type these entries in Windows Search and press Enter):

    %AppData%
    %LocalAppData%
    %ProgramData%
    %WinDir%

After you are finished, reboot the PC in normal mode.

Finally, you should always think about the protection of crypto-ransomwares. In order to protect your computer from Sigrun and other ransomwares, use a reputable anti-spyware, such as ReimageIntego, SpyHunter 5Combo Cleaner or Malwarebytes

How to prevent from getting ransomware

Stream videos without limitations, no matter where you are

There are multiple parties that could find out almost anything about you by checking your online activity. While this is highly unlikely, advertisers and tech companies are constantly tracking you online. The first step to privacy should be a secure browser that focuses on tracker reduction to a minimum.

Even if you employ a secure browser, you will not be able to access websites that are restricted due to local government laws or other reasons. In other words, you may not be able to stream Disney+ or US-based Netflix in some countries. To bypass these restrictions, you can employ a powerful Private Internet Access VPN, which provides dedicated servers for torrenting and streaming, not slowing you down in the process.

Data backups are important – recover your lost files

Ransomware is one of the biggest threats to personal data. Once it is executed on a machine, it launches a sophisticated encryption algorithm that locks all your files, although it does not destroy them. The most common misconception is that anti-malware software can return files to their previous states. This is not true, however, and data remains locked after the malicious payload is deleted.

While regular data backups are the only secure method to recover your files after a ransomware attack, tools such as Data Recovery Pro can also be effective and restore at least some of your lost data.

About the author
Jake Doevan
Jake Doevan - Computer technology expert

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References
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