Sysfrog Ransomware

Also Known As: Sysfrog virus
Distribution: Low
Damage level: Severe

Sysfrog ransomware removal instructions

What is Sysfrog?

Discovered by Michael Gillespie, Sysfrog is a malicious program categorized as ransomware. Programs of this type are designed to encrypt files: they lock files and keep them that state until developers are paid. I.e., ransomware victims are encouraged to buy decryption tools from these cyber criminals. Sysfrog adds the ".sysfrog" extension to each file (it also prepends "[]"). For example, ".jpg." becomes "[]1.jpg.sysfrog". It also creates a ransom message within the "how_to_decrypt.txt" file, which can be found in folders that contain encrypted files.

The "how_to_decrypt.txt" contains a short ransom message stating that all files were encrypted, and to retrieve them, victims must pay 0.3 of a Bitcoin by transferring to a Bitcoin wallet address provided. It also contains an email address ( that can be used to contact Sysfrog's developers. Like most ransomware developers, these cyber criminals supposedly send a decryption tool after payment, however, most do not send anything. They receive the money (cryptocurrency) and then ignore their victims. Unfortunately, the only way to decrypt files in these cases is using tools held only by the cyber criminals who developed the ransomware. Typically, ransomware-type programs encrypt files using strong encryption algorithms that are impossible to decrypt without using the correct tools. As cyber criminals cannot be trusted, the best option in these cases is to restore files using data backups.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:

Sysfrog decrypt instructions

Examples of other programs of this type are .good, Rectot and Virus-encoder. Most ransomware-type programs encrypt files and keep them in that state until a ransom is paid (decryption tool/key is purchased). Typically, two main differences between these programs are ransom size and encryption algorithm used for encryption. It is virtually impossible to decrypt data without contacting the cyber criminals who created the ransomware. Decryption without their involvement is possible only if the ransomware is still in development, contains bugs/flaws, and so on. Therefore, maintain data backups and store them on a remote server (such as Cloud) or unplugged storage device.

How did ransomware infect my computer?

Common ways to proliferate ransomware-type and other malicious programs are by using untrustworthy software download sources, fake (unofficial) software updaters, spam campaigns, trojans and software 'cracking' tools. Some examples of download sources that can be used to proliferate malware are Peer-to-Peer networks (torrent clients, eMule and so on), freeware download websites, file hosting websites, unofficial websites and other similar sources. They are used to proliferate malicious programs by disguising them as harmless files. When people download and open them, however, they are often tricked into installing high-risk infections. Unofficial, fake software updating tools can be used to download and install malicious programs rather than the software updates/fixes, or to exploit bugs/flaws of outdated software. Spam campaigns can be used to proliferate malware via attachments that are presented in emails sent from cyber criminals. These attachments are often MS Office documents (such as Word, Excel etc.), archive files (like ZIP, RAR), PDFs, executables (for example, .exe files), JavaScript files and so on. When opened, these files download and install ransomware or other malware. Trojans are malicious programs that cause chain infections, however, to proliferate viruses, they must already be installed on the system. Software 'cracking' tools are programs that supposedly allow users to bypass activation of licensed software/operating systems, however, there are many cases whereby cyber criminals use them to proliferate malware. These programs download and install computer infections rather than activating software free of charge.

Threat Summary:
Name Sysfrog virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .sysfrog (also prepends filenames with "[]" string).
Ransom Demanding Message how_to_decrypt.txt text file.
Ransom Amount .3 Bitcoin
Cyber Criminal Contact
Symptoms Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password-stealing trojans and malware infections can be installed together with a ransomware infection.

To eliminate Sysfrog virus our malware researchers recommend scanning your computer with Spyhunter.
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Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

How to protect yourself from ransomware infections?

To avoid computer infections, be careful with irrelevant emails that are received from unknown/suspicious addresses, especially if they contain attachment. Emails of this type should not be trusted. Update all installed software updating implemented functions or tools provided by official software developers. Any other (unofficial) updaters/tools should not be trusted. The same applies to software activation - this should not be done using 'cracking' tools. These are illegal and often lead to computer infections. Furthermore, download apps and files using official websites. Do not use dubious channels (third party downloaders, installers, unofficial pages, etc.). Have a reputable anti-virus or anti-spyware suite installed and active (enabled). These programs deal with various threats and usually detect and eliminate them before they can cause any damage. If your computer is already infected with Sysfrog, we recommend running a scan with Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in Sysfrog ransomware text file ("how_to_decrypt.txt"):

Your files have been encrypted.
If you want to get your files back, send 0.3 bitcoin to my wallet
my wallet address : 3FoiK3TTfA42Du34aFWTV9qTg5XChVh18c
If you have any questions, please contact us.

Your Id:-
Your Key:

Payment site hxxps://
Payment site hxxps://
Payment site hxxp://
Payment site hxxp://
Officail Mail:


Screenshot of files encrypted by Sysfrog (".sysfrog" extension):

Files encrypted by Sysfrog

Sysfrog ransomware removal:

Instant automatic removal of Sysfrog virus: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Spyhunter is a professional automatic malware removal tool that is recommended to get rid of Sysfrog virus. Download it by clicking the button below:
▼ DOWNLOAD Spyhunter By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the Sysfrog virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the Sysfrog ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining Sysfrog ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of Sysfrog are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by Sysfrog, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as Sysfrog ransomware.

Note that Windows 10 Fall Creators Update includes a "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default, this feature automatically protects files stored in the Documents, Pictures, Videos, Music, Favorites as well as Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here is more information on how to get this update and add an additional protection layer from ransomware infections.

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove Sysfrog ransomware:

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global virus and spyware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

QR Code
Sysfrog virus QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of Sysfrog virus on your mobile device.
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Platform: Windows

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