Cyborg ransomware: what it is and how to remove it

Cyborg ransomware is the threat that marks encrypted files using .petra file appendix and gets installed on the PC from an email about needed updates. The email notification with "Install the latest Update now" tricks people into prompting the Critical Microsoft Windows Update install that triggers an executable file named bitcoingenerator.exe.

Facts checked October 6, 2026. Removal steps tested on Windows 11 (26H2) and checked against Microsoft's and the browser makers' current documentation. Sections marked as our earlier report are the original text: they describe the threat as it was then and have not been reviewed since. The 2026 status, the removal steps and the questions are current.

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Screenshot of Cyborg ransomware: virus
Cyborg ransomware as our 2019 report showed it.

Cyborg ransomware: summary

DistributionInfected email attachments with malicious files, fake updates promoting messages, torrent sites, pirated software, malicious files, other malware set to deliver crypto-extortion based threats
NameCyborg ransomware
File marker.petra, .777 marks all files encrypted by the virus and indicates useless data
Ransom noteCyborg_DECRYPT.txt – a text file containing the message from virus developers where hackers suggest victims paying up as soon as possible to get their files back supposedly
Ransom amountCybercriminals demand at least $300 in Bitcoin. Some campaigns reported about ransom amount going up to $500 for the alleged decryption key
Contact emailspetra-mail.ru, marceldeneud@yandex.com
Removal

Scan the PC with security software to find and remove the malware and anything installed with it. Fortect scans Windows for malware and repairs the system files and settings it damaged.

Remove it nowTo use the full-featured product, you have to purchase a license for Fortect. The scan is free.
Show 13 more facts
DangerSuch money-oriented threat actors don't care for your belongings, so the main focus is encryption and ransom demands. There is no guarantee that paying could ensure file recovery, so you pay for nothing in the long run and can lose your files permanently. Also, ransomware can load additional scripts and affect the machine further when the encryption is already done
Detection namesNo Microsoft detection name is known
Encrypted file extension.777
DecryptorNo free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates
DamageNot recorded in the old report
TypeFile-encrypting ransomware
SymptomsFiles renamed with a new extension and a ransom note left in folders
Evidence4 write-ups by security sites; no sample analysed yet
Encrypted files.777
Attacker contactsmarceldeneud@yandex.com
Free decryptorNo free decryptor is known (checked 6 October 2026)
First seen25 November 2019
Facts checked6 October 2026
  • File extension: .777
  • Note file: Cyborg_DECRYPT.txt
  • Contact: marceldeneud@yandex.com

From our report of Nov 2019 · not reviewed since

More from our earlier report on Cyborg ransomware

  • For a proper Cyborg ransomware removal, you should get anti-malware tool and run on the machine to fully find and eliminate malicious files, programs, the initial virus
  • Besides encrypting your personal data like photos, documents, or archives, Cyborg ransomware virus can alter system settings and important parts like directories or startup preferences.
  • You should try to fix the virus damage and repair system data using a system tool like

How Cyborg ransomware behaves

From our report of Nov 2019 · not reviewed since

Cyborg ransomware is the threat that gets loaded on the machine via fraudulent Windows update notification emails

Cyborg ransomware is the threat that marks encrypted files using .petra file appendix and gets installed on the PC from an email about needed updates.

The email notification with "Install the latest Update now" tricks people into prompting the Critical Microsoft Windows Update install that triggers an executable file named bitcoingenerator.exe. Hidden behind the .jpg type of the file, this executable launches the ransomware payload on the system immediately.

The threat first was spotted at the beginning of November, but the particular Cyborg ransomware virus campaign that reportedly involves .777 file marker and those emails with Windows 10 updates, was discovered in the middle of the same month.

When malware is done encoding files, it deletes itself, places a copy of the virus as a file bot.exe in the root of the infected device, and a typical ransom note file in the text file named Cyborg_DECRYPT.txt on the desktop and in various folders with affected data.

The message is generated for virus victims, so they can know what to do next. Unfortunately, the option malware creators suggest involves paying the ransom for the alleged decryption tool that is not the best solution, as previous incidents show.

Cyborg ransomware gets dropped when spam campaign tricks people into script delivery by claiming that the email is sent from Microsoft officials and encourages to install the latest Windows 10 update. The fake update attachment is an executable file even though .jpg file extension is on the filename. In reality, the malicious .NET file is an executable that downloads malware on the infected system and triggers a file encryption process.

According to people who managed to tool more into the attack, this mid-November Cyborg ransomware campaign appended all the files with .777 extension and loaded the ransom note on the compromised machine's Desktop. Cyborg_DECRYPT.txt provided information about the ransom amount - $500 in Bitcoin that should be sent to the particular wallet provided on the text file already.

Cyborg ransomware shows a message on the Desktop directly that replaces the wallpaper, but that picture contains only information about encrypted files and notes that the full ransom message placed as a text file.

The ransom message seems to be generated as any typical message from crypto-extortionists, so don't trust them and try to react as soon as possible by eliminating the threat and ignoring the following or a similar note entirely:

Also, a second step after the payment should be writing an email to the described email address. However, we don't recommend paying or contacting criminals. You should ignore the message instead and remove Cyborg ransomware from the machine until the PC gets damaged permanently.

Cyborg ransomware message encourages you to contact a new email address - marceldeneud@yandex.com that also seems to be related to Russia as a previous petra-mail.ru, but there is no relation to any hacking groups that could be confirmed. Nevertheless, the message should be ignored, and the machine cleaned as soon as possible if you want to get back to the virus-free machine.

At least three different samples got investigated, but there is not enough information to state that Cyborg ransomware is decryptable or belongs to a particular virus family. There is a tool called Cyborg Builder ransomware, so there might be more news about the threat in the future. But the builder contains a link to the Russian version of the same builder on another website beside GitHub.

Researchers report that Cyborg ransomware can be created and spread by anyone who can obtain the builder. It can be spread using various forms of gateways and spamming campaigns. This is a crafted cryptovirus that uses random extensions to mislead victims from identifying the particular strain.

It means that Cyborg ransomware removal may become a huge issue and a question among online users when more and more people will get victimized. Experts also note that cybercriminals who deliver threats like this can only worry about their own benefits, so trusting anyone is a bad choice, even though the ransom note creates trust between you and the developer.

Also, since Cyborg ransomware is a virus that hides all over the computer system, you should check important parts of the system with PC repair tools, system applications like . This software may indicate corrupted, damaged, or outdated files in folders of your system like directories, registry.

Even when you get rid of the malware itself, virus damage can cause more issues, so you need to take care of everything to get back to work on the safe computer. Additional tips for your data recovery can be found below the article.

Screenshot of Cyborg ransomware: virus
Cyborg ransomware in our 2019 report.
Cyborg ransomware: cyborg cryptovirus
Cyborg ransomware in our 2019 report.

From our report of Nov 2019 · not reviewed since

Infected email attachments get hidden behind scary or legitimate-looking email subject lines

Don't fall victim to scamming campaigns by paying close attention to processes and learning to look for red flags.

Targeted users in various campaigns receive emails with either the subject line about financial information or, in this case, windows update message.

"Install Latest Microsoft Windows Update now!" or "Critical Microsoft Windows Update!" statements should already be suspicious since Windows Updates are not pushed through emails. Your operating system should indicate that there is an update you may need to install. So this is a red flag number one - a common type of email and the sender.

These particular emails contain notifications like "Please install the latest critical update from Microsoft attached to this email" and attachments that have an easily triggered executable. You only need to download the file, and malicious scripts can do whatever developers designed them for.

How to avoid such infection? Be cautious about such malicious emails, and look for red flags, be more suspicious and cautious, delete anything that is not familiar, or creates questions. Clean the email message more often and delete emails that get there without expectations.

From our report of Nov 2019 · not reviewed since

Terminate Cyborg ransomware using professional AV tools and make sure to repair virus damage

To fully eliminate a threat like Cyborg ransomware virus, it is important to know more about the type of malware you got affected by.

There is no one cure for cyber infections, even though anti-malware programs can eliminate most of them, there are additional processes and tips you need to remember.

Since this is the crypto-extortion based malware, paying is not the option for Cyborg ransomware removal. Even when you pay the ransom and your files get recovered, the system is still infected and damaged. To get your compromised device to work properly again, you need to clean the system entirely.

The best tool for you that we can recommend is anti-malware software - programs that work on particular malware databases that can indicate malicious activities for you should also remove Cyborg ransomware. Unfortunately, removing the virus is not going to recover your encrypted data or fix damaged parts of the system. Additional steps after the virus removal:

[GI=method-1]Reboot the machine in Safe Mode with Networking to fully eliminate Cyborg ransomware virus

[GI=method-2]System Restore is the feature that helps with ransomware since it can recover machine in a previous state

Windows Previous Version is the method for recovering individual files

When System Restore gets enabled, you can use Windows Previous Versions and recover affected data

ShadowExplorer is the feature helpful for encoded files

When Shadow Volume Copies are left untouched, ShadowExplorer can be a helpful option for data recovery

Decryption for files affected by Cyborg ransomware is not possible yet

  • rely on tools like , , or and repair the needed parts of your PC that virus affected;
  • use data backups or file recovery software to restore encrypted data.

The Cyborg ransomware note

a ransom note left in folders

------------------------ ALL YOUR FILES ARE ENCRYPTED BY CYBORG RANSOMWARE ------------------------

Don't worry, you can return all your files!

All your files like documents, photos, databases and other important are encrypted

What guarantees do we give to you?

You can send one of your encrypted file and we decrypt it for free.

You must follow these steps To decrypt your files :

1) Send $300 bitcoin to wallet :9e3d4e3fad796f4eb15962b74fb2e55fe47

2) write on our e-mail :petra-mail.ru

Your personal ID :

How to remove Cyborg ransomware

Tools you'll need

All of these are free except where noted. Download them on a clean device if the infected PC is offline.

  • A USB stick: to keep the ransom note, two or three encrypted files and screenshots off the infected PC.
  • Microsoft Defender Offline: built into Windows 11 and Windows 10; scans before Windows starts, so running malware cannot hide.
  • Microsoft Safety Scanner: a second, portable scanner with current signatures; each download works for 10 days.
  • ID Ransomware: identifies the family from the note and one encrypted file and says whether a decryptor exists.
  • No More Ransom: the free decryptors from police and security companies; check it again every few months.
  • Fortect (optional): scans Windows for malware and repairs the system files and settings it damaged. The free scan is in the box above.

How to remove Cyborg ransomware and get your files back

Work in this order.

Disconnecting comes first, removal comes before any restore, and nothing here asks you to contact the attackers.

  1. Step 1: Disconnect the PC and unplug backup drives

    Unplug the network cable or turn off Wi-Fi, and disconnect USB drives, external disks and network shares, so Cyborg ransomware cannot reach more files. Pause OneDrive, Google Drive or Dropbox sync, because synced folders upload the encrypted copies over the good ones.

    Leave the PC on but offline while you read the next steps, since a restart can let the ransomware run again. This applies to Windows 11 and Windows 10 alike.

    Windows 11 quick settings with Wi-Fi turned off
    Windows 11: turn off Wi-Fi to take the PC offline.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  2. Step 2: Save the ransom note and confirm the family

    Your files now end in .777 and the instructions are in Cyborg_DECRYPT.txt. Save both to a USB stick, a copy of the note and two small encrypted files, before anything else.

    On another device, check them with ID Ransomware or Crypto Sheriff: the family name decides which decryptor, if any, can help. Keep the note's ID and contact line for your report.

    A ransom note text file next to encrypted files in File Explorer
    Windows 11: the ransom note and encrypted files to copy for identification.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  3. Step 3: Check for a free decryptor

    Our last check found that for Cyborg ransomware, no free decryptor is known (checked 6 October 2026). Look again yourself in the No More Ransom list and the free decryptor pages of Emsisoft, Avast and Kaspersky, which add new families every year.

    A decryptor needs the ransomware gone first, or it encrypts the files again. Keep at least one copy of the encrypted files on an external drive, even if no tool works yet.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  4. Step 4: Remove the ransomware before you restore or decrypt

    Removing Cyborg ransomware does not bring the files back, but it has to come first. Start with Defender's Full scan, then the offline scan from the same Scan options page, which checks the disk before Windows loads.

    If the scan cannot start, use Safe Mode with Networking. Delete the ransom notes only after you have saved a copy, because removal tools sometimes leave them behind on Windows 11 and Windows 10.

    Windows Security Scan options with Microsoft Defender Antivirus offline scan selected
    Windows 11: Windows Security > Virus & threat protection > Scan options.

    Full procedure with screenshots: Run a Microsoft Defender Offline scan

  5. Step 5: Look for shadow copies of the files

    Windows keeps shadow copies for restore points and backups, and some ransomware fails to delete them. vssadmin list shadows in an administrator Command Prompt tells you at once whether any exist.

    If they do, right-click the folder that held your files, open Properties > Previous Versions, select a version from before the attack, and click Open to check it before you Restore or copy the files out. Windows 11 and Windows 10 both have the tab.

    Command Prompt running vssadmin list shadows
    Windows 11: vssadmin list shadows shows whether shadow copies exist.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  6. Step 6: Restore the files from a backup or recover deleted originals

    A backup made before the attack is the surest way back. Connect it only once the PC is clean, then restore from File History, Windows Backup, OneDrive's Restore your OneDrive or your own external copies.

    Without a backup, try file recovery: the originals that Cyborg ransomware deleted may still be on the disk until something overwrites them. Install nothing new on the drive you want to recover from on the Windows 11 or Windows 10 PC.

    Full procedure with screenshots: Recover deleted files (Recycle Bin, backups, OneDrive) On uGetFix

Instructions for each browser and system

The detailed steps for every browser and system this guide covers. Open the one you use.

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.

Report it and recover your files

Report it

Report the attack even if you do not expect the files back: insurers and banks ask for the report number, and police use the contacts in the note to link cases.

United States
FBI IC3 · FTC ReportFraud

Give the victim ID, the note and the date the files were encrypted. A business that holds personal data may also have to notify its data protection authority, in the EU within 72 hours.

Make the next attack harmless

Cyborg ransomware could only hurt the files that had no second copy, and the signs (files that end in .777 and no longer open) showed exactly which ones those were.

The 3-2-1 rule fixes that:

  • three copies
  • two media
  • one disconnected

A practical version for a home PC: OneDrive or another cloud backup with version history, plus an external disk that you plug in once a week for File History and then unplug. Test a restore now and then by opening a few files from the backup on another device.

Details, schedules and what not to back up are in our 3-2-1 backup guide for Windows.

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 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 can also be effective and restore at least some of your lost data.

Questions about Cyborg ransomware

How do I open .777 files?

You cannot open them by renaming or with another program, because the content of files ending in .777 has been encrypted. The only ways back are a working decryptor for the family, or clean copies from elsewhere:

  • OneDrive versions
  • File History
  • an offline backup drive
  • Previous Versions if the ransomware did not delete them

Identify the family first by uploading the ransom note and one encrypted file to ID Ransomware or No More Ransom. Avoid websites and programs that promise to open any encrypted file; they do not work and some are scams.

Is there a free Cyborg ransomware decryptor?

We last checked on 6 October 2026, and for Cyborg ransomware no free decryptor is known. We check No More Ransom, which collects free tools from police and security companies, and the decryptor pages of the major antivirus vendors. A working decryptor exists only when the encryption has a flaw or the keys were leaked or seized.

Ignore sites and videos that offer a "Cyborg ransomware decryptor" for download or for a fee: these are usually scams or malware. Real decryptors are free and come from known security companies or law enforcement. Keep the encrypted files in case a tool appears later.

Are ransomware recovery services legitimate?

Some are, but read the offer carefully. Genuine data-recovery firms recover deleted originals from disks or rebuild damaged files, and they say so. Others promise to "decrypt any ransomware" for a fixed price, which is impossible without the key; they quietly pay the attackers and keep a margin, sometimes without telling the victim.

Be especially careful with services that contact you after you post about the attack online. Ask for references, a written method and a no-result-no-fee clause, and check the free tools on No More Ransom first.

Should I pay the ransom?

We advise against it, and so do the FBI, Europol and national cyber agencies. Payment does not guarantee a working tool: some attackers never reply, some tools damage files, and some variants have no decryptor at all. Paying also funds further attacks and can make you a target again.

Before considering payment, try every recovery option in this guide and report the attack. Companies must involve their legal adviser and insurer, because payments to sanctioned groups can be illegal. If files are truly irreplaceable, store the encrypted copies and wait; decryptors sometimes appear later.

How did Cyborg ransomware get on my computer?

The way Cyborg ransomware spreads has not been documented yet, so look at your own recent activity. On home PCs, ransomware most often comes with cracked programs, game cheats, key generators and fake updates, or with an e-mail attachment that was opened. On business networks, attackers usually log in through Remote Desktop with a stolen or guessed password.

Think back to what was downloaded or installed in the days before files that end in .777 and no longer open, and check the Downloads folder and Installed apps sorted by date. Keep anything suspicious for your report, but do not run it again.

Did Cyborg ransomware steal my files or passwords?

We do not know yet. Nothing published so far shows data theft by Cyborg ransomware, but the only confirmed sign is files that end in .777 and no longer open, which says nothing about what happened before. Many current ransomware attacks copy files or run a password stealer first, so it is wise to act as if they did.

From a clean device, change the passwords that were saved in the browsers on this PC, starting with e-mail and banking, sign out of all sessions and turn on two-step verification. Watch bank statements and account activity for the next few weeks.

Is Cyborg ransomware the same as other ransomware with a similar name?

Not necessarily. Ransomware names come from the file extension, the note or a word in the code, so unrelated families often end up with similar names, and one family can appear under several names. The difference matters: a decryptor or advice for one family does not fit another and can damage files.

Compare the ending added to your files and the exact name of the note with the summary table at the top of this guide, then upload the note and one encrypted file to ID Ransomware from a clean device. If the result names another family, follow the guide for that family instead.

Can I delete Cyborg_DECRYPT.txt?

Yes, the note itself is harmless text and deleting it does not affect your files. Keep at least one copy first, outside the infected PC. Cyborg_DECRYPT.txt contains your personal ID and the attackers' contact details, which identification services use to tell which family encrypted your files, and which a decryptor may need later.

Police reports also ask for it. Once you have saved a copy, you can remove the notes from every folder after the ransomware program has been removed and your files are restored or backed up.

Should I reinstall Windows after the .777 attack?

Reinstalling removes the ransomware but not the encryption: your files ending in .777 stay encrypted afterwards. So first copy the encrypted files and the ransom note to a separate drive, in case a decryptor appears later. Then decide:

  • a clean-up with an offline scan is often enough for home PCs
  • while a full reset is safer if remote access was involved
  • scans keep finding new items

Restore your backups only after the PC is clean, and change passwords from another device.

Will Fortect remove Cyborg ransomware?

Fortect scans Windows for malware and unwanted programs and repairs the system files and settings they change, and its free scan shows what it finds on your PC before you decide anything.

For Cyborg ransomware, follow the plan above as well: the browser steps take back permissions and settings that no scanner treats as a threat, and uninstalling the program that brought it removes the source.

Run Microsoft Defender's full scan and, if anything was found, its offline scan as a second opinion. If the symptoms are gone after the plan and both scans are clean, there is nothing more to do.

Sources

More removal guides

Cyborg ransomware in the news

Questions and experiences: Cyborg ransomware

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