Calum ransomware: what it is and how to remove it
Calum ransomware is one of the newest versions belonging to Phobos ransomware. The purpose of this malware is to target English speakers, infiltrate their Windows machines, and scan the system for encryptable documents/files.
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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Calum ransomware: summary
| Distribution | Ransomware infections, including Calum virus, are most commonly distributed via email spam, software cracks, vulnerable RDP, infectious ads/links, and other similar locations |
|---|---|
| Name | Calum ransomware |
| Type | Ransomware infection/file-encrypting malware/ransom-demanding virus |
| Appendix | Once the malware places itself on the Windows computer system and uses symmetric or asymmetric encryption to lock up data, the affected components end up with the .Calum extension added |
| Ransom note(s) | The ransomware virus places info.hta and info.txt ransom demanded messages on the desktop and also a copy in each folder that includes locked documents and files |
| Demanded price | Even though there is no current ransom price number given, hackers are likely to demand an amount between $100 and $2000 that needs to be transferred in BTC or another type of cryptocurrency |
| 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 16 more facts
| Email addresses | The criminals provide annali1984@protonmail.com or annali1984@cock.li email addresses as a way to make communication with them |
|---|---|
| Family | Phobos ransomware |
| Detection names | No Microsoft detection name is known |
| Contact | annali1984@protonmail.com, annali1984@cock.li |
| Encrypted file extension | .calum |
| Decryptor | No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates |
| Damage | Not recorded in the old report |
| Symptoms | Files renamed with a new extension, a ransom note left in folders and a Windows Security "Threats found" notification |
| Evidence | 5 write-ups by security sites; no sample analysed yet |
| Encrypted files | .calum |
| Ransom note | info.hta |
| Attacker contacts | annali1984@protonmail.com |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 26 November 2019 |
| Microsoft Defender name | Ransom:Win32/Phoenix.BW |
| Facts checked | 6 October 2026 |
Which name will your scanner show?
Microsoft's name for Calum ransomware is Ransom:Win32/Phoenix.BW.
Defender sorts threats by category first, so the word before the colon tells you what kind of program was found, even if the family name means nothing to you.
Do not search for a removal tool by the detection name alone; fake "removal tools" use the same keywords. How the naming works is explained in our guide to antivirus detection names.
- File extension:
.calum - Note file:
info.hta - Contact:
annali1984@protonmail.com
From our report of Nov 2019 · not reviewed since
More from our earlier report on Calum ransomware
- You need to get rid of the infection ASAP.
- Perform the process only automatically to avoid possible mistakes and damage
- If the malware has touched some system components on your Windows computer machine, try repairing them with the help of software
How Calum ransomware behaves
From our report of Nov 2019 · not reviewed since
Calum ransomware - a Phobos family member that appends the .Calum extension to each locked component and demands a BTC ransom
Calum ransomware is one of the newest versions belonging to Phobos ransomware.
The purpose of this malware is to target English speakers, infiltrate their Windows machines, and scan the system for encryptable documents/files. Once the malicious program detects all files that can be locked, it executes a symmetric or asymmetric algorithm that blocks the data and appends the .Calum extension to each affected component.
Furthermore, Calum virus drops the info.hta and info.txt ransom notes that bring ransom demands which have to be met, otherwise, the victims will not be able to recover their data. The criminals try to scare people by claiming that no other tool will help and encourage victims to write them via annali1984@protonmail.com or annali1984@cock.li email addresses and also obtain Bitcoin cryptocurrency for the ransom payment.
Calum ransomware brings more than just file encryption and inadequate ransom demands. This malicious string might modify some Windows Registry entries and inject hazardous processes in your Task Manager section once entering your Windows machine. This way the cyber threat will be assured that it will reboot and reload itself each time when the user turns on his/her computer system.
Continuously, such alterings might allow Calum ransomware to run a system scanning process once in a while and go in search of newly-encryptable documents and files. Also, the malware might try to avoid antivirus detection by running specific commands, destroy Shadow Copies of locked data, or damage the hosts file in order to prevent users from accessing cybersecurity-related web pages where they might find reliable information towards Calum ransomware removal.
Our recommendation would be not to fall for the tricks that Calum ransomware might try to put on you as there might be some better solutions than paying the criminals.
Besides, you always risk losing your money for nothing while paying hackers as these people might appear to be only scammers. Even though the ransom note claims that the decryption tool will be provided after the ransom payment, this type of data might be completely false:
Calum ransomware might tend to carry additional malware into the system. There are a lot of ransomware strains that come attached with a Trojan horse as this way the developers can double their benefits. If you postpone the elimination process of the ransomware virus, you might not even notice that additional malware has been added to your computer system before it is too late.
After the cyber threat leaves your computer, you can try repairing damaged files with . Also, go down to the end of this article and read through all of the data recovery methods some of which might let you bring your data back to primary state.
The content of Calum ransomware has also been included in the database of VirusTotal website. We have found that 53 out of 69 AV engines are able to detect the malware-laden files. Some of the detection names include Win32:Malware-gen, TR/Crypt.XPACK.Gen, Trojan.Ransom.Phobos.F, Trojan.Ransom.Phobos.F (B), Ransom.Phobos, Ransom:Win32/Phoenix.BW, etc.
From our report of Nov 2019 · not reviewed since
Ransomware appearance is a common thing in the cybersecurity field
Regarding the latest news reports by security researchers, ransomware infections are commonly distributed on random user computers and also have been targetting reputable healthcare firms, banking organizations, and so on.
These notorious viruses might result in the loss of important information or money if the victim agrees to pay and inadequate price in order to receive the decryption tool.
Calum ransomware is just a small fish in the ocean regarding the thousands of other ransomware viruses released. However, every infection is dangerous, should be avoided and removed if injected into someone's computer system. Besides from Phobos releasing new versions fastly, Djvu ransomware also does not fall behind. The developers have already let out around 200 versions that belong to this malware category.
From our report of Nov 2019 · not reviewed since
The termination process of Calum ransomware (Phobos variant)
Phobos seems to be including various versions of ransomware into its family line and Calum ransomware is one of them.
If you ever encounter this malicious infection on your Windows computer system, you should not let it stay there for long as many damaging actions might be performed during then.
We always recommend using automatical software for succeeding in processes such as Calum ransomware removal as manual elimination might bring more damage to the infected system if completed wrong. First, scan the system with antivirus software such as or .
After you remove Calum ransomware, you can try employing which might help you to repair the corrupted files that have been touched by the malware.
[GI=method-1]If the ransomware virus has initiated some malicious processes on your Windows computer system, you can try to disable the operations by booting your machine in Safe Mode with Networking:
[GI=method-2]If you have been looking for ways to stop malicious tasks from running on your computer, you can try booting up via System Restore. To do that, follow these guidelines:
Use this piece of software if you have been looking for a tool to unlock your data with. Even though there is no 100% guarantee that the program will work, it is definitely better trying this product than paying the big ransom.
Use Windows Previous Versions feature for data recovery tasks.
Employ this type of feature to reverse some files back to their previous states. However, just ensure that you have activated System Restore in the past, otherwise, this tool might not work properly.
Try activating Shadow Explorer and restore some data.
If the ransomware infection did not permanently eliminate or damage the Shadow Volume Copies of your locked files, you can give this piece of software a try.
Currently, cybersecurity experts are still working on the official Calum ransomware decryption tool.
From our report of Nov 2019 · not reviewed since
Multiple techniques are used for ransomware distribution daily
Security specialists from ZonderVirus.nl state that hackers think of numerous ways how to distribute their products for a wider range of people.
Ransomware viruses are one of the most dangerous infections that lean on spreading techniques such as email spam, software cracks, malicious updates, infected files/ads/links, exploit kits, vulnerable RDP, etc.
One of the most popular spreading ways is through email spam campaigns where cybercriminals pretend to be from reliable shipping companies such as FedEx or DHL and tend to deliver "shipment information" or "order confirmation" via a hyperlink or attachment that truly is the infectious payload.
Furthermore, ransomware is also commonly distributed via software cracks that can be found on unsecured downloading sources and p2p networks such as The Pirate Bay. Get all of your products and services only from reputable developers and originals websites, otherwise, you might easily end up with malware on your computer system.
Continuously, vulnerable RDP protection such as including a weak password or none security code at all might also allow crooks to hack the RDP remotely, brute force the password into the system, or just connect remotely without putting any big effort into the process.
Make sure that you always use strong and reliable passwords that include not only letters or just numbers but both of them combined together and even some symbols added.
The Calum ransomware note
All your files have been encrypted!
All your files have been encrypted due to a security problem with your PC. If you want to restore them, write us to the e-mail annali1984@cock.li
Write this ID in the title of your message -
In case of no answer in 24 hours write us to this e-mail:annali1984@protonmail.com
You have to pay for decryption in Bitcoins. The price depends on how fast you write to us. After payment we will send you the tool that will decrypt all your files.
Free decryption as guarantee
Before paying you can send us up to 5 files for free decryption. The total size of files must be less than 4Mb (non archived), and files should not contain valuable information. (databases,backups, large excel sheets, etc.)
How to obtain Bitcoins
The easiest way to buy bitcoins is LocalBitcoins site. You have to register, click 'Buy bitcoins', and select the seller by payment method and price.
hxxps://localbitcoins.com/buy_bitcoins
Also you can find other places to buy Bitcoins and beginners guide here:
hxxp://www.coindesk.com/information/how-can-i-buy-bitcoins/
Attention!
Do not rename encrypted files.
Do not try to decrypt your data using third party software, it may cause permanent data loss.
Decryption of your files with the help of third parties may cause increased price (they add their fee to our) or you can become a victim of a scam.
How to remove Calum 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 Calum 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
Unplug the network cable or turn off Wi-Fi, and disconnect USB drives, external disks and network shares, so Calum 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: 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
Your files now end in
.calumand the instructions are ininfo.hta. 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.
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
Our last check found that for Calum 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
Step 4: Remove the ransomware before you restore or decrypt
Removing Calum 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 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
Windows keeps shadow copies for restore points and backups, and some ransomware fails to delete them.
vssadmin list shadowsin 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.
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
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 Calum 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
- 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.
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.
Backups: the 3-2-1 rule
Keep three copies of files that matter, on two kinds of storage, with one copy offline or off-site.
A disk that stays plugged in is reached by malware like Calum ransomware together with the PC; one you connect only for the backup is not.
On Windows 11, File History keeps versions on an external drive, and OneDrive keeps earlier versions of synced files. Before restoring anything, make sure the PC no longer shows files that end in .calum and no longer open.
Setting it up step by step: 3-2-1 backups on Windows 11 and 10.
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 Calum ransomware
How do I open .calum files?
You cannot open them by renaming or with another program, because the content of files ending in .calum 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.
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.
Is there a free Calum ransomware decryptor?
We last checked on 6 October 2026, and for Calum 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 "Calum 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.
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 Calum ransomware get on my computer?
The way Calum 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 .calum 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 Calum ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by Calum ransomware, but the only confirmed sign is files that end in .calum 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 Calum 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 info.hta?
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. info.hta 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.
Defender removed Ransom:Win32/Phoenix.BW. Am I safe now?
Often yes, but check two things. First, whether the detection was caught on arrival: a file in Downloads or in an archive that Defender quarantined before it ran is the best case.
Second, whether Ransom:Win32/Phoenix.BW comes back. If it returns, or if Protection history shows several different detections around the same date, something on the PC keeps producing the file and needs to be found.
Run a full scan and, if anything remains, an offline scan. If the category names a password stealer or a backdoor, change your passwords from another device even if the file is gone.
Will Fortect remove Calum 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 Calum 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
- Cryptomathic: Symmetric Key Encryption - why, where and how it's used in banking (read October 6, 2026)
- Wikipedia: Shadow Copy (read October 6, 2026)
- VirusTotal: 53 engines detected this file (read October 6, 2026)
- ZonderVirus: ZonderVirus.nl (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)