What is SunnyDay Ransomware?
SunnyDay is a malicious program that has been reported to infect computer systems and restrict access to personal files. It is currently circling around the web in active attack campaigns. The virus adjusts essential system settings. As a consequence, the overall system security is lowered. The worst impact is the encryption of personal files. Encryption of personal files leads to changes in both their code and their names. A file originally named cover.jpg will be renames to cover.jpg.SunnyDay after being encrypted by the ransomware. Based on all nasty issues, hackers try to extort a hefty ransom fee from victims. Supposedly, their decryption tool for .SunnyDay files will restore data and enable you to use it again.
Beware that any negotiations with cybercriminals suggested by the ransom message !-Recovery_Instructions-!.txt should be avoided. Keep up with this article to learn more information about the SunnyDay ransomware virus, discover how to remove it step-by-step, and check out some alternative data recovery methods.

SunnyDay Summary
Name | SunnyDay also known as Generic.Ransom.LockCrypt.3.C0267EF9, Win64:RansomX-gen [Ransom], Ransom:Win32/Filecoder.AA!MTB |
Type | Ransomware, Cryptovirus |
Short Description | A data locker ransomware that utilizes strong cihper algorithms like RSA and AES to encrypt valuable files. Then it demands a ransom for their decryption. |
Symptoms | Important files are locked and renamed with the extension .SunnyDay. A ransom message appears on the computer to request a ransom fee for a decryption tool. |
Distribution Method | Spam Emails, Email Attachments, Torrents |
Detection Tool |
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SunnyDay Virus – How Did I Get It?
To get SunnyDay ransomware on your PC, you need to run its payload file without noticing. The methods that may initiate the attack are different but the most preferred by hacker is malspam (email spam campaigns). Other shady methods that can trick you to run ransomware on your computer include:
- Software cracks;
- Malicious web links;
- Freeware featuring compromised installers;
- Fake software update notifications, etc.
All listed methods attempt to hide the malicious program so that people can run it without suspecting the damage it will cause to their devices and personal data.
SunnyDay Virus – What Does It Do?
The activation of the payload file of the SunnyDay virus is not enough for the completion of all attack stages. The ransomware needs to establish additional malicious files on the system and then start executing them one by one to compromise all system settings that could support the infection flow. The complex attack leads to lots of nasty changes that continue impacting system security until the complete removal of the ransomware from the infected PC.
When SunnyDay ransomware reaches the data encryption stage, it utilizes a built-in cipher module designed to transform parts of the original code of target files. By the use of strong cipher algorithms like AES and RSA the ransomware locks your personal files and prevents you from accessing data they store.
All of the following types of files may be encrypted by the threat:
- Audio files;
- Document files;
- Video files;
- Backup files;
- Image files;
- Banking credentials, etc.
Files corrupted by SunnyDay ransomware are all marked with a specific extension of the same name. The .SunnyDay suffix appended to the original names of some of your files is a sure sign that they have been compromised by the cryptovirus.
Analyses of the code of SunnyDay ransomware reveal that the ransomware misuses registry keys for their special functionalities that control the automatic execution of certain files every time the OS loads. The ransomware compromises the following directories to run its malicious files automatically:
→ HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
Just like other ransomware strains discovered in the wild SunnyDay ransomware drops its ransom note file on the system at the end of the attack. The file could show up on the screen to inform you the following:
! YOUR NETWORK HAS BEEN COMPROMISED !
All your important files have been encrypted!
ANY ATTEMPT TO RESTORE A FILE WITH THIRD-PARTY SOFTWARE WILL PERMANENTLY CORRUPT IT.No software available on internet can help you. We are the only ones able to solve your problem.
We gathered data from different segment of your network. These data are currently stored on a private server and will be immediately destroyed after your payment.
If you decide to not pay, we will keep your data stored and contact press or re-seller or expose it on our partner’s website.
We only seek money and do not want to damage your reputation or prevent your business from running.
If you take wise choice to pay, all of this will be solved very soon and smoothly.
You will can send us 2-3 non-important files and we will decrypt it for free to prove we are able to give your files back.
Contact us.
restoreassistance_net@wholeness.business
restoreassistance_net@decorous.cyou
In the subject write – id-VA0328497918
It is stored on the infected machine under the name !-Recovery_Instructions-!.txt. The message has the purpose to persuade you to contact malware authors and ask them how to transfer a ransom fee, probably in any cryptocurrency.
Keep in mind that hackers who stand behind nasty SunnyDay ransomware attacks cannot be trusted. They could steal your money by providing no effective decryption solution for .SunnyDay files. And a ransom payment does not guarantee the recovery of .SunnyDay files. This step should be avoided. Don’t risk your security and privacy by negotiating with cybercriminals.

Remove SunnyDay Ransomware
The so-called SunnyDay ransomware is a threat with highly complex code that disrupts system security in order to encrypt personal files. Hence, the infected system could be used in a secure manner again only after you remove all malicious files and objects created by the ransomware. All steps presented in the ransomware removal guide below aim to help you to remove malicious files from your infected PC in full.
Beware that manual ransomware removal is suitable for more experienced computer users. If you don’t feel comfortable with the manual steps navigate to the automatic part of the guide. It is also worth mentioning that personal data remains encrypted even after the complete removal of SunnyDay ransomware.
Attention! SensorsTechForum strongly recommends that all malware victims should look for assistance only by reputable sources. Many guides out there claim to offer free recovery and decryption for files encrypted by ransomware viruses. Be advised that some of them may only be after your money.
As a site that has been dedicated to providing free removal instructions for ransomware and malware since 2014, SensorsTechForum’s recommendation is to only pay attention to trustworthy sources.
How to recognize trustworthy sources:
- Always check "About Us" web page.
- Profile of the content creator.
- Make sure that real people are behind the site and not fake names and profiles.
- Verify Facebook, LinkedIn and Twitter personal profiles.
About the SunnyDay Research
The content we publish on SensorsTechForum.com, this SunnyDay how-to removal guide included, is the outcome of extensive research, hard work and our team’s devotion to help you remove the specific malware and restore your encrypted files.
How did we conduct the research on this ransomware?
Our research is based on an independent investigation. We are in contact with independent security researchers, and as such, we receive daily updates on the latest malware and ransomware definitions.
Furthermore, the research behind the SunnyDay ransomware threat is backed with VirusTotal and the NoMoreRansom project.
To better understand the ransomware threat, please refer to the following articles which provide knowledgeable details.
References
1. How to Recognize Spam Emails with Ransomware
2. How Does Ransomware Encryption Work?
3. How to Decrypt Ransomware Files
4. Ransomware Getting Greedier and Bigger, Attacks Increase by 40%
5. 1 in 5 Americans Victim of Ransomware
How to Remove SunnyDay from Windows.
Step 1: Boot Your PC In Safe Mode to isolate and remove SunnyDay
1. Hold Windows Key + R.

2. The "Run" Window will appear. In it, type "msconfig" and click OK.

3. Go to the "Boot" tab. There select "Safe Boot" and then click "Apply" and "OK".

4. When prompted, click on "Restart" to go into Safe Mode.

5. You can recognise Safe Mode by the words written on the corners of your screen.

Step 2: Uninstall SunnyDay and related software from Windows
Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:
1. Hold the Windows Logo Button and "R" on your keyboard. A Pop-up window will appear.

2. In the field type in "appwiz.cpl" and press ENTER.

3. This will open a window with all the programs installed on the PC. Select the program that you want to remove, and press "Uninstall"

Step 3: Clean any registries, created by SunnyDay on your computer.
The usually targeted registries of Windows machines are the following:
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
You can access them by opening the Windows registry editor and deleting any values, created by SunnyDay there. This can happen by following the steps underneath:
1. Open the Run Window again, type "regedit" and click OK.

2. When you open it, you can freely navigate to the Run and RunOnce keys, whose locations are shown above.

3. You can remove the value of the virus by right-clicking on it and removing it.

Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.
Step 4: Scan for SunnyDay with SpyHunter Anti-Malware Tool
1. Click on the "Download" button to proceed to SpyHunter's download page.
2. After you have installed SpyHunter, wait for it to update automatically.
3. After the update process has finished, click on the 'Malware/PC Scan' tab. A new window will appear. Click on 'Start Scan'.
4. After SpyHunter has finished scanning your PC for any files of the associated threat and found them, you can try to get them removed automatically and permanently by clicking on the 'Next' button.
Video Guide for Automatic and Fast Removal
Step 5 (Optional): Try to Restore Files Encrypted by SunnyDay.
Ransomware infections and SunnyDay aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.
1. Download the recommended Data Recovery software by clicking on the link underneath:
Simply click on the link and on the website menus on the top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.
Step 6: How to Restore Files Encrypted by Ransomware (Video Guide)
Get rid of SunnyDay from Mac OS X.
Step 1: Uninstall SunnyDay and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
2. Find Activity Monitor and double-click it:
3. In the Activity Monitor look for any suspicious processes, belonging or related to SunnyDay:
4. Click on the "Go" button again, but this time select Applications. Another way is with the ⇧+⌘+A buttons.
5. In the Applications menu, look for any suspicious app or an app with a name, similar or identical to SunnyDay. If you find it, right-click on the app and select “Move to Trash
”.
6. Select Accounts, after which click on the Login Items preference.
Your Mac will then show you a list of items that start automatically when you log in. Look for any suspicious apps identical or similar to SunnyDay. Check the app you want to stop from running automatically and then select on the Minus (“-“) icon to hide it.
7. Remove any left-over files that might be related to this threat manually by following the sub-steps below:
- Go to Finder.
- In the search bar type the name of the app that you want to remove.
- Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
- If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.
In case you cannot remove SunnyDay via Step 1 above:
In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:
1: Click on "Go" and Then "Go to Folder" as shown underneath:
2: Type in "/Library/LauchAgents/" and click Ok:
3: Delete all of the virus files that have similar or the same name as SunnyDay. If you believe there is no such file, do not delete anything.
You can repeat the same procedure with the following other Library directories:
→ ~/Library/LaunchAgents
/Library/LaunchDaemons
Tip: ~ is there on purpose, because it leads to more LaunchAgents.
Step 3 (Optional): Try to Restore Files Encrypted by SunnyDay.
Ransomware infections and SunnyDay aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.
1. Download the recommended Data Recovery software by clicking on the link underneath:
Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.
SunnyDay FAQ
What is SunnyDay ransomware and how does it work?
SunnyDay is a ransomware infection - the malicious software that enters your computer silently and blocks either access to the computer itself or encrypt your files.
Many ransomware viruses use sophisticated encryption algorithm how to make your files inaccessible. The goal of ransomware infections is to demand that you pay a ransom payment to get access to your files back.
How does SunnyDay ransomware infect my computer?
Via several ways.SunnyDay Ransomware infects computers by being sent via phishing e-mails, containing virus attachment.
This attachment is usually masked as an important document, like an invoice, bank document or even a plane ticket and it looks very convincing to users.
After you download and execute this attachment, a drive-by download occurs and your computer is infected with the ransomware virus.
Another way, you may become a victim of SunnyDay is if you download a fake installer, crack or patch from a low reputation website or if you click on a virus link. Many users report getting a ransomware infection by downloading torrents.
How to open .SunnyDay files?
You can't. At this point the .SunnyDay files are encrypted. You can only open them once they are decrypted.
Decryptor did not decrypt my data. What now?
Do not panic and backup the files. If a decryptor did not decrypt your .SunnyDay files successfully, then do not despair, because this virus is still new.
One way to restore files, encrypted by SunnyDay ransomware is to use a decryptor for it. But since it's a new virus, advised that the decryption keys for it may not be out yet and available to the public. We will update this article and keep you posted as soon as this decryptor is released.
How Do I restore ".SunnyDay" files (Other Methods)?
Yes, sometimes files can be restored. We have suggested several file recovery methods that could work if you want to restore .SunnyDay files.
These methods are in no way 100% guarantee that you will be able to get your files back. But if you have a backup, your chances of success are much greater.
How do I get rid of SunnyDay ransomware virus?
The safest way and the most efficient one for the removal of this ransomware infection is the use a professional anti malware software. It will scan for and locate SunnyDay ransomware and then remove it without causing any additional harm to your important .SunnyDay files.
Also, keep in mind that viruses like SunnyDay ransomware also install Trojans and keyloggers that can steal your passwords and accounts. Scanning your computer with an anti-malware software will make sure that all of these virus components are removed and your computer is protected in the future.
What to Do If nothing works?
There is still a lot you can do. If none of the above methods seem to work for you, then try these methods:
- Try to find a safe computer from where you can can login on your own line accounts like One Drive, iDrive, Google Drive and so on.
- Try to contact your friends, relatives and other people so that they can check if they have some of your important photos or documents just in case you sent them.
- Also, check if some of the files that were encrypted it can be re-downloaded from the web.
- Another clever way to get back some of your files is to find another old computer, a flash drive or even a CD or a DVD where you may have saved your older documents. You might be surprised what will turn up.
- You can also go to your email account to check if you can send any attachments to other people. Usually what is sent the email is saved on your account and you can re-download it. But most importantly, make sure that this is done from a safe computer and make sure to remove the virus first.
More tips you can find on our forums, where you can also asks any questions about your ransomware problem.
How to Report Ransomware to Authorities?
In case your computer got infected with a ransomware infection, you can report it to the local Police departments. It can help authorities worldwide track and determine the perpetrators behind the virus that has infected your computer. Below, we have prepared a list with government websites, where you can file a report in case you are a victim of a cybercrime:
Cyber-security authorities, responsible for handling ransomware attack reports in different regions all over the world:
- Germany - Offizielles Portal der deutschen Polizei
- United States - IC3 Internet Crime Complaint Centre
- United Kingdom - Action Fraud Police
- France - Ministère de l'Intérieur
- Italy - Polizia Di Stato
- Spain - Policía Nacional
- Netherlands - Politie
- Poland - Policja
- Portugal - Polícia Judiciária
- Greece - Cyber Crime Unit (Hellenic Police)
- India - Mumbai Police - CyberCrime Investigation Cell
- Australia - Australian High Tech Crime Center
Reports may be responded to in different timeframes, depending on your local authorities.