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Sigrun ransomware. How to remove? (Uninstall guide)

removal by Jake Doevan - - | Type: Ransomware

Sigrun ransomware is a crypto-locker that demands payment in cryptocurrency for file release

Sigrun ransomware

Sigrun is a ransomware virus that recently has been discovered by security researchers.[1] As soon as malware executes its payload, it locks up all video, audio, text, picture and other files, and modifies their name by adding .sigrun file extension. Soon after that, the virus drops a ransom note “RESTORE-SIGRUN.txt” into each of the infected folders and also opens up a browser tab with the same message in .html format. The user is then asked to contact hackers via 

Name Sigrun
Type Ransomware
File extension .sigrun
Ransom notes RESTORE-SIGRUN.txt and RESTORE-SIGRUN.html
Contact email
Distribution Spam emails, fake downloads, repacked software installers, etc.
Symtoms Unusable files
Elimination Use reputable security software Reimage, Plumbytes Anti-MalwareWebroot SecureAnywhere AntiVirus or Malwarebytes Anti Malware

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 provided email has .ch extension, which may suggest that the culprits are Swiss. We may never know, however.

Sigrun virus spreads via contaminated attachments in spam emails. Users who open the .txt, .pdf, .doc, .zip or other affixed file 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 Sigrun ransomware first and then proceed with file recovery.

Users are urged to contact criminals via the 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 Sigrun authors three files which they would decode for free.

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.

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 Reimage or Plumbytes Anti-MalwareWebroot SecureAnywhere AntiVirus 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.

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 password 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 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 Sigrun virus is exterminated.

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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If you failed to remove infection using Reimage, submit a question to our support team and provide as much details as possible.
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More information about this program can be found in Reimage review.
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Manual Sigrun virus Removal Guide:

Remove Sigrun using Safe Mode with Networking

To enter Safe Mode with Networking, follow these steps:

  • Step 1: Reboot your computer to Safe Mode with Networking

    Windows 7 / Vista / XP
    1. Click Start Shutdown Restart OK.
    2. When your computer becomes active, start pressing F8 multiple times until you see the Advanced Boot Options window.
    3. Select Safe Mode with Networking from the list Select 'Safe Mode with Networking'

    Windows 10 / Windows 8
    1. Press the Power button at the Windows login screen. Now press and hold Shift, which is on your keyboard, and click Restart..
    2. Now select Troubleshoot Advanced options Startup Settings and finally press Restart.
    3. Once your computer becomes active, select Enable Safe Mode with Networking in Startup Settings window. Select 'Enable Safe Mode with Networking'
  • Step 2: Remove Sigrun

    Log in to your infected account and start the browser. Download Reimage or other legitimate anti-spyware program. Update it before a full system scan and remove malicious files that belong to your ransomware and complete Sigrun removal.

If your ransomware is blocking Safe Mode with Networking, try further method.

Remove Sigrun using System Restore

You can eliminate Sigrun using System Restore function:

  • Step 1: Reboot your computer to Safe Mode with Command Prompt

    Windows 7 / Vista / XP
    1. Click Start Shutdown Restart OK.
    2. When your computer becomes active, start pressing F8 multiple times until you see the Advanced Boot Options window.
    3. Select Command Prompt from the list Select 'Safe Mode with Command Prompt'

    Windows 10 / Windows 8
    1. Press the Power button at the Windows login screen. Now press and hold Shift, which is on your keyboard, and click Restart..
    2. Now select Troubleshoot Advanced options Startup Settings and finally press Restart.
    3. Once your computer becomes active, select Enable Safe Mode with Command Prompt in Startup Settings window. Select 'Enable Safe Mode with Command Prompt'
  • Step 2: Restore your system files and settings
    1. Once the Command Prompt window shows up, enter cd restore and click Enter. Enter 'cd restore' without quotes and press 'Enter'
    2. Now type rstrui.exe and press Enter again.. Enter 'rstrui.exe' without quotes and press 'Enter'
    3. When a new window shows up, click Next and select your restore point that is prior the infiltration of Sigrun. After doing that, click Next. When 'System Restore' window shows up, select 'Next' Select your restore point and click 'Next'
    4. Now click Yes to start system restore. Click 'Yes' and start system restore
    Once you restore your system to a previous date, download and scan your computer with Reimage and make sure that Sigrun removal is performed successfully.

Bonus: Recover your data

Guide which is presented above is supposed to help you remove Sigrun from your computer. To recover your encrypted files, we recommend using a detailed guide prepared by security experts.

Do not contact cybercrooks, even if you do not have a backup ready. Instead, ignore their demands and follow alternative data recovery methods.

If your files are encrypted by Sigrun, you can use several methods to restore them:

Try Data Recovery Pro

This tool was created to restore broken or accidentally deleted files. Nevertheless, in some cases, this application might help users whose files are affected by ransomware.

Windows Previous Versions Feature might be useful

You can only reclaim files one-by-one. Hence, large amount of data might not be recoverable. Additionally, for the feature to work, you should have had System Restore function enable before the attack occurred.

  • Find an encrypted file you need to restore and right-click on it;
  • Select “Properties” and go to “Previous versions” tab;
  • Here, check each of available copies of the file in “Folder versions”. You should select the version you want to recover and click “Restore”.

ShadowExplorer might be able to recover your data

If you are lucky enough and the virus did not delete shadow volume copies, you can recover all your files with this application.

  • Download Shadow Explorer (;
  • Follow a Shadow Explorer Setup Wizard and install this application on your computer;
  • Launch the program and go through the drop down menu on the top left corner to select the disk of your encrypted data. Check what folders are there;
  • Right-click on the folder you want to restore and select “Export”. You can also select where you want it to be stored.

There is no decryptor available yet

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 Reimage, Plumbytes Anti-MalwareWebroot SecureAnywhere AntiVirus or Malwarebytes Anti Malware

About the author

Jake Doevan
Jake Doevan - Computer technology expert

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