Octopus ransomware: what it is and how to remove it
Octopus ransomware is a Phobos virus variant that was first spotted in the wild in early November 2019 and is known to be spread via poorly protected RDP connections. Just as its predecessors, malware aims to encrypt all personal data on the machine and the connected networks/drives and then blackmail victims into paying a ransom in Bitcoin for the decryption software that only developers of Octopus virus have access to.
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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Octopus ransomware: summary
| Threat name | Octopus ransomware |
|---|---|
| Type | Cryptovirus |
| Malware family | Phobos ransomware |
| Infection means | Octopus virus is known to be spread via Remote Desktop connections, although malware might be distributed via other methods, such as spam emails, fake updates, software cracks, exploits, etc. |
| Encryption method | Ransomware uses the AES encryption algorithm to lock all personal data on the infected device |
| File extension | All personal pictures, videos, documents, etc., are appended with .octopus marker, although full file modification looks as follows: [name].[original extension].id[XXXXXXXX-XXXX].[octopusdoc@mail.ee].octopus. Example of an encrypted file: instructions.pdf.id[8E95D737-2497].[octopusdoc@mail.ee].octopus |
| 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 18 more facts
| Ransom note | Two ransom notes are placed on the infected machine: info.txt (brief), info.hta (an extensive note that is shown in a pop-up window) |
|---|---|
| Contact | Victims are asked to contact cybercriminals to begin ransom payment negotiations via octopusdoc@mail.ee or octopusdoc@mail.cc |
| Ransom size | 0.31 Bitcoin (may vary) |
| Termination | Use reputable anti-malware software to locate and eliminate the malicious components from your system |
| File decryption | The only safe way to decrypt .octopus files is by restoring them from backups that were set up prior to the infection. In case no backups are available, the only option is to try data recovery software – check out the guide below |
| Detection names | No Microsoft detection name is known |
| Encrypted file extension | .octopus |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Distribution | Not recorded in the old report |
| Damage | Not recorded in the old report |
| Name | Octopus ransomware |
| Symptoms | Files renamed with a new extension and a ransom note left in folders |
| Evidence | 5 write-ups by security sites; no sample analysed yet |
| Encrypted files | .octopus |
| Attacker contacts | octopusdoc@mail.ee |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 11 November 2019 |
| Facts checked | 6 October 2026 |
- File extension:
.octopus - Note file:
info.txt - Contact:
octopusdoc@mail.ee
From our report of Nov 2019 · not reviewed since
More from our earlier report on Octopus ransomware
- Ransomware might render the system partially broken, as anti-malware software cannot repair some ransomware-affected system files.
- Due to this, OS reinstallation might be sometimes necessary.
The Octopus ransomware note
!!!All of your files are encrypted!!!
To decrypt them send e-mail to this address: octopusdoc@mail.ee.
If we don't answer in 24h., send e-mail to this address: octopusdoc@airmail.cc
How to remove Octopus 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 Octopus 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.
Step 1: Disconnect the PC and unplug backup drives
Octopus ransomware encrypts everything it can reach, including drives and shares you connect later. Cut the network first: cable out, or Wi-Fi off from the taskbar.
Then unplug every USB stick and backup disk and pause cloud sync, so the encrypted versions do not replace your online copies. Do not reconnect any of them until the ransomware is removed from the Windows 11 or Windows 10 PC.
Windows 11: turn off Wi-Fi to take the PC offline. Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 2: Save the ransom note and confirm the family
Copy
info.txtand one or two files ending in.octopusto a USB stick, and leave the originals where they are.From another device, upload the note and a sample file to ID Ransomware or No More Ransom's Crypto Sheriff, which name the family from the note, the extension and the file structure.
Write down the contact address and your personal ID from the note, because a decryptor or the police may ask for them.
Warning: Never contact the attackers from the infected Windows 11 or Windows 10 PC.
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
Step 3: Check for a free decryptor
For Octopus ransomware, no free decryptor is known (checked 6 October 2026). Search the family name in the No More Ransom decryption tools list and in the free decryptors of Emsisoft, Avast and Kaspersky, because new tools appear years after an attack.
Important: Keep the encrypted files even if nothing works today, and do not pay before every free option is ruled out: payment does not guarantee a working key.
Decryptors run on Windows 11 and Windows 10, but only after the ransomware itself is removed.
Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 4: Remove the ransomware before you restore or decrypt
Restoring or decrypting files while Octopus ransomware still runs lets it encrypt them again. Run a Full scan in Windows Security > Virus & threat protection > Scan options, then the Microsoft Defender Antivirus (offline scan).
If the ransomware blocks Windows Security, start Safe Mode with Networking and scan from there. Some families install a password stealer as well, so let both scans finish on Windows 11 or Windows 10.
Windows 11: Windows Security > Virus & threat protection > Scan options. Full procedure with screenshots: Run a Microsoft Defender Offline scan
Step 5: Look for shadow copies of the files
Open Command Prompt as administrator and run
vssadmin list shadows. If it lists copies dated before the attack, right-click a folder with encrypted files in File Explorer, choose Properties > Previous Versions, and open or restore a version from before that date.ShadowExplorer, a free tool, shows the same copies when the tab is empty or hidden. Most current families delete shadow copies, so an empty list is normal, but the check takes two minutes on Windows 11 or Windows 10.
Windows 11: vssadmin list shadows shows whether shadow copies exist. Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files
Step 6: Restore the files from a backup or recover deleted originals
Restore from an external backup, File History or OneDrive's version history, choosing a date before the attack. Connect the backup drive only after the scans are clean, or the ransomware encrypts it too.
If there is no backup, file recovery software can sometimes find the deleted originals, because some ransomware writes an encrypted copy and deletes the original file.
Stop writing to the drive and try recovery on Windows 11 or Windows 10 before new files overwrite the space.
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
- Click Start > Shutdown > Restart > OK.
- 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.
- Select Safe Mode with Networking from the list.
Windows 10 / Windows 8
- Right-click on Start button and select Settings.
- Scroll down to pick Update & Security.
- On the left side of the window, pick Recovery.
- Now scroll down to find Advanced Startup section.
- Click Restart now.
- Select Troubleshoot.
- Go to Advanced options.
- Select Startup Settings.
- Press Restart.
- Now press 5 or click 5) Enable Safe Mode with Networking.
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:
- Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
- Click on More details.
- Scroll down to Background processes section, and look for anything suspicious.
- Right-click and select Open file location.
- Go back to the process, right-click and pick End Task.
- Delete the contents of the malicious folder.
Step 3. Check program Startup
- Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
- Go to Startup tab.
- Right-click on the suspicious program and pick Disable.
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:
- Type in Disk Cleanup in Windows search and press Enter.
- 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).
- Scroll through the Files to delete list and select the following:
Temporary Internet Files
Downloads
Recycle Bin
Temporary files - Pick Clean up system files.
- 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.
From our report of Nov 2019 · not reviewed since
Octopus ransomware - a dangerous cyber infection that asks for 0.31 BTC for the encrypted file recovery
Octopus ransomware is a Phobos virus variant that was first spotted in the wild in early November 2019 and is known to be spread via poorly protected RDP connections.
Just as its predecessors, malware aims to encrypt all personal data on the machine and the connected networks/drives and then blackmail victims into paying a ransom in Bitcoin for the decryption software that only developers of Octopus virus have access to.
In the case of this version, all personal pictures, videos, images, documents, databases, MS Office, and other files get marked with .octopus file extension and are no longer available to be used.
After file encryption, Octopus ransomware delivers two ransom notes: info.txt, which is a standard message from the perpetrators and info.hta - a pop-up window that shows more detailed instructions.
The attackers ask victims to contact them via octopusdoc@mail.ee or octopusdoc@mail.cc emails, and then demand the ransom to be paid for the decryption tool. While the price might vary (criminals do not specify the ransom amount in the message), in the known instances, they demanded 0.31 BTC for file release.
Phobos is one of the most well-established ransomware families in the wild - it accounts for around 9% of worldwide infections of cryptolockers. While it mostly targets corporations and public entities, Octopus ransomware might infect regular PC users as well.
The main propagation method of this malware strain is via the RDP connections, credentials of which were stolen by other cybercriminal groups and sold on the black market. Since late December 2018, the malware is establishing a name for itself, as it released dozens of versions throughout its short time of the operation (in comparison to other ransomware families like Djvu).
Once installed, Octopus ransomware starts preparing a Windows system for the file encryption process:
System modifications might also prevent easy Octopus ransomware removal by hindering System Restore function or disabling anti-malware software. To avoid that, victims should access Safe Mode with Networking to temporarily pause these effects.
After that, Octopus ransomware initiates the file encryption process with AES cipher, and each of the files located on the host computer receives .octopus extension, although the complete extension looks as follows: instructions.pdf.id[8E95D737-2497].[octopusdoc@mail.ee].octopus - the ID varies based on the victim.
The Octopus virus ransom note info.txt states the following:
Another note, which comes as a pop-up window, explains everything in more detail - users are informed that they can get a test decryption service. Crooks offer to decrypt up to five files for free, as long as they do not include valuable information.
However, this is one of the tricks that many ransomware authors use, and Octopus ransomware developers are no exception - they are trying to gain victims' trust and prove the decryption is possible.
Nevertheless, there were several instances where users did not receive the decryption tool, even after paying the ransom. Therefore, paying crooks is always a risk, as loss of money along with loss of files might be devastating to many.
Instead, users should remove Octopus ransomware by scanning the computer with anti-malware. One of the alternatives to paying criminals is trying data recovery software - check out the recovery section below for more details.
- Deletes Shadow Volume Copies
- Establishes a network connection with C&C server
- Deletes, installs and opens various registry entries
- Executes Shell Commands, etc.
From our report of Nov 2019 · not reviewed since
Secure your Remote Desktop connection to prevent ransomware attacks
Phobos is a large malware family, and most of the attacks are performed with brute-force attacks - cybercriminals scan the internet for insecure Remote Desktop (RDP) connections and then use a predetermined list of credentials to gain remote access to the host machine. In some cases, the credentials might be acquired from the underground forums due to data leaks in various security breaches.
Once the access is granted, malicious actors can control the computer remotely and, while the brute-forcing process is usually automated, they download and install the malicious payload manually. This allows hackers to act "on the spot," and this method has been extremely prevalent when corporate entities and high-profile victims are targeted.
To avoid ransomware attacks via RDP, adequate protection measures should be employed. Security experts advise the following:
Because bad actors can use several other methods for malware distribution (spam email, software cracks, fake updates, etc.), it is vital to protect your machine with reputable anti-malware solutions.
- Disconnect from the Remote Desktop as soon as the feature is not needed anymore;
- Use strong passwords and change them frequently - do not reuse them;
- Never use default TCP port for your connection - 3389, as attackers can easily identify;
- Keep all your software updated so that hackers could not abuse software vulnerabilities to get into your machine.
From our report of Nov 2019 · not reviewed since
Attempt to restore your files only after you remove Octopus ransomware from your machine
While it is possible to remove Octopus ransomware manually, it is a huge task even for IT professionals.
Malware makes thousands of changes to the infected systems, and reverting them might be extremely difficult and would take an enormous amount of time. Thus, this operation should be conducted with powerful anti-malware software - it would detect all the malicious components on the infected Windows machine and eliminate them at once.
However, the Octopus virus might prevent security software from operating normally. In such a case, you should access Safe Mode and perform a full scan from there - we explain how to do that below.
Only after you complete Octopus ransomware removal, you can proceed with the data recovery process. If the opposite is performed, all the recovered files will be encrypted by the virus repeatedly, making the whole restoration process useless. Before you do that, however, you should backup all the encrypted files, as the data might get corrupted in the process.
[GI=method-1]If Octopus ransomware is interfering with your anti-malware tool, access Safe Mode with Networking and perform a full system scan from there:
[GI=method-2]You can eliminate the virus with System Restore:
Make use of Windows Previous Versions Feature
If you had System Restore enabled before you got infected with octopus ransomware, try Windows Previous Versions Feature.
ShadowExplorer might recover all your files
Due to various inconsistencies within ransomware code, it might fail to remove Shadow Volume Copies. If that is the case, you should be able to recover your files with ShadowExplorer.
No decryption tool is currently available
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
- United Kingdom
- Report Fraud (formerly Action Fraud) · NCSC
- Australia
- ReportCyber (ASD)
- EU countries
- Europol: national reporting sites
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.
Protect the files you restore
Restore only after the scans are clean and the PC no longer shows files that end in .octopus and no longer open; otherwise the restored copies can be damaged again.
Then build a backup that survives the next infection:
- one copy in the cloud with version history
- one on an external drive that is disconnected between backups
- the working copy on the PC
Version history matters because a backup that syncs damaged files overwrites the good ones.
How to do this with the tools built into Windows: the 3-2-1 backup rule on Windows.
Choose a proper web browser and improve your safety with a VPN tool
Online spying has got momentum in recent years and people are getting more and more interested in how to protect their privacy online.
One of the basic means to add a layer of security - choose the most private and secure web browser. Although web browsers can't grant full privacy protection and security, some of them are much better at sandboxing, HTTPS upgrading, active content blocking, tracking blocking, phishing protection, and similar privacy-oriented features.
However, if you want true anonymity, we suggest you employ a powerful VPN - it can encrypt all the traffic that comes and goes out of your computer, preventing tracking completely.
Lost your files? Use data recovery software
While some files located on any computer are replaceable or useless, others can be extremely valuable.
Family photos, work documents, school projects - these are types of files that we don't want to lose. Unfortunately, there are many ways how unexpected data loss can occur:
- power cuts
- Blue Screen of Death errors
- hardware failures
- crypto-malware attack
- even accidental deletion
To ensure that all the files remain intact, you should prepare regular data backups. You can choose cloud-based or physical copies you could restore from later in case of a disaster. If your backups were lost as well or you never bothered to prepare any, can be your only hope to retrieve your invaluable files.
Questions about Octopus ransomware
Is there a decryptor for .octopus files?
That depends on the family behind the .octopus extension, which this guide cannot confirm yet from the reports alone. Check No More Ransom and ID Ransomware with your ransom note and one encrypted file; they list families with free tools.
If none exists today, keep the encrypted files and a copy of the note on a separate drive, because decryptors are sometimes published months later after flaws are found or servers are seized. Never buy a decryptor from a website that is not the security company that made it.
How do I open .octopus files?
You cannot open them by renaming or by choosing another program. The .octopus ending shows that Octopus ransomware encrypted the content, and only the matching key can reverse it. Renaming a file back to .docx or .jpg changes nothing except the icon, and it can confuse a future decryptor, so leave the names as they are.
To get the content back, use a backup, an unencrypted copy elsewhere, or a decryptor listed on No More Ransom if one exists for Octopus ransomware. Store the encrypted files on an external disk until then.
Did Octopus ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by Octopus ransomware, but the only confirmed sign is files that end in .octopus 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.
How did Octopus ransomware get on my computer?
The way Octopus 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 .octopus 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.
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.
Can a data-recovery company decrypt my files for a fee?
Only if a decryptor already exists or the company pays the attackers for you. Some "ransomware recovery" services advertise that they can decrypt families with no known flaw; in practice they negotiate with the attackers and add their own fee. Others use the same free tools listed on No More Ransom.
Before you hire anyone, ask in writing how they will recover the files, whether they will contact the attackers and what happens if they fail. A legitimate service answers clearly. If a free decryptor exists for your family, you can run it yourself.
Is Octopus 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.
What does info.txt tell me about the ransomware?
Quite a lot. The file name info.txt, the wording, the contact addresses and the format of the personal ID are typical for each family. Uploading the note together with one encrypted file to ID Ransomware or No More Ransom's Crypto Sheriff usually names the family within seconds.
That name decides your options: some families have free decryptors, some can be partially recovered, and some cannot be decrypted at all. The note's claims about stolen data should be taken seriously but not at face value.
Should I reinstall Windows after the .octopus attack?
Reinstalling removes the ransomware but not the encryption: your files ending in .octopus 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 Octopus 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 Octopus 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
- ZDNet: FBI warns companies about hackers increasingly abusing RDP connections (read October 6, 2026)
- Emsisoft: Ransomware statistics for 2019: Q2 to Q3 report (read October 6, 2026)
- Avast: Ransomware attacks via RDP choke SMBs (read October 6, 2026)
- Dieviren: Dieviren (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)