Mailto ransomware: what it is and how to remove it
Mailto ransomware is the family of malware that focuses on encrypting files and damaging Windows devices. Recent variants have hit Toll Group in January 2020, while initial release dates back to August 2019.
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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Mailto ransomware: summary
| Name | Mailto ransomware |
|---|---|
| Also known as | Kokoklock ransomware, Koko ransomware, NetWalker ransomware |
| Symptoms | Files appended with a random extension become unusable; a ransom-demanding note dropped in many different folders |
| Main targets | Newer versions were spotted hitting large companies and businesses |
| Encryption algorithm | Salsa20 |
| File extension | .[random], includes the contact email. Thus appendix gets added at the end of original name of the previously available data. Extension example: .mailto[kokoklock@cock.li].1be018 |
| 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 15 more facts
| Contact | kokoklock@cock.li, pabpabtab@tuta.io, hamlampampom@cock.li, galgalgalhalk@tutanota.com, sevenoneone@cock.li, kavariusing@tutanota.com |
|---|---|
| Ransom note | victims'_ID-Readme.txt or random_extension-Readme.txt |
| Termination | You should always employ powerful anti-malware when dealing with serious PC infections like this. So remove NetWalker ransomware from the system with a proper AV tool that can detect and delete traces of this virus |
| Detection names | No Microsoft detection name is known |
| Encrypted file extension | .1be018 |
| 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 |
| Type | File-encrypting ransomware |
| Evidence | 5 write-ups by security sites; no sample analysed yet |
| Encrypted files | .1be018 |
| Attacker contacts | kokoklock@cock.li |
| Free decryptor | No free decryptor is known (checked 6 October 2026) |
| First seen | 6 February 2020 |
| Facts checked | 6 October 2026 |
- File extension:
.1be018 - Note file:
Readme.txt - Contact:
kokoklock@cock.li
From our report of Feb 2020 · not reviewed since
More from our earlier report on Mailto ransomware
- To remediate damaged system files and ensure the machine is fully recovered from the infection, scan it with
How Mailto ransomware behaves
From our report of Feb 2020 · not reviewed since
NetWalker ransomware is a multi-variant malware that targets large companies for bigger ransom payments
Mailto ransomware is the family of malware that focuses on encrypting files and damaging Windows devices.
Recent variants have hit Toll Group in January 2020, while initial release dates back to August 2019. The virus affects all devices connected to the network it targets, so this is a powerful threat that paralyzes various enterprises and everyday users' devices.
It is known that the ransomware payload file impersonates Sticky Password software, so it can be executed and use the embedded configuration that loads all the needed data for encryption processes and other activities. This is the method used to hide malicious processes and mask the encryption.
Once inside the system, Mailto ransomware virus looks for videos, pictures, documents, databases, music, and other personal files to perform encryption on. Using a Salsa20 cipher, it makes files unreachable and then marks data with a random appendix that usually consists of six alphanumeric characters (for example, .1be018 .d0e731).
A ransom note -Readme.txt is also dropped, which explains that users have to email crooks via kokoklock@cock.li or pabpabtab@tuta.io to have a chance to decrypt the compromised files.
Criminals behind Mailto ransomware ask for a ransom to be paid in Bitcoin or another cryptocurrency, although the exact sum is unknown - it may also vary from victim to victim. Security experts who managed to get hold of the decryption tool from the attackers noted that it was named "Netwalker Decryptor" in the header, so the same ransomware can be called a NetWalker virus too.
Mailto ransomware, otherwise known as Kokoklock ransomware or NetWalker, is malware that was first spotted in early September 2019. This file-locking virus does not seem to have any relations to other ransomware families but has the same goal - money extortion. Fortunately, this virus is recognized by nearly over 50 security applications, so its termination can be performed without any troubles.
Since NetWalker ransomware gets around the globe using various techniques, networks can get encrypted due to infected email attachment sent to the employe or after the visit on malicious websites laced with malicious codes. It is not known how specifically Mailto gets on targeted systems.
Regardless of how you might have infected your computer with the virus, your main goal should be Mailto ransomware removal. To achieve that, you should employ reputable security software.
Note that we should first remove Mailto ransomware from your computer before proceeding to file recovery, as all the backups or retrieved files will be repeatedly locked. Currently, there is not an easy way to decrypt the data if no backup is available.
Luckily, security experts work on decryption tools that become available to the public, although it is not known how much time it might take to create for this particular Kokoklock ransomware strain.
Another option that might help is third-party recovery software, although chances of recovering all of the NetWalker ransomware encrypted data using it are relatively low. We provide the guide below - please check the file recovery section below.
From our report of Feb 2020 · not reviewed since
Mailto or NetWalker?
First instances when Mailto ransomware affected machines and researchers got a hold of samples, the investigation showed that the decryption tool offered by the criminals is named NetWalker Decrypter.
In most cases, malware experts name the threat by something that developers state in the text file or base the name on the file appendix.
Since the decryption tool was discovered by MalwareHunterTeam the name of the virus family got questioned. This is how developers referred to their product, so the threat is known as NetWalker ransomware now. However, that is not changing any functionalities or removal processes. Victims still call this threat Mailto or generally indicate the file appendix, not the name of the ransomware that researchers use.
These newer releases of NetWalker/Mailto ransomware are now targetting bigger businesses and companies, institutions because blackmailing is more successful this way. Criminals demand bigger amounts from people whose networks get encrypted and can be surer that decryption tools get purchased when data is more valuable.
The example of the more recent NetWalker ransom note:
Despite all those claims and possible offers in the text file, you should think twice before you pay cybercriminals for the decryptor - they might simply scam you and never send you the required tool. Even the large companies often restrain from such options due to the high risks of getting data permanently damaged and focuses on NetWalker ransomware removal instead.
Cybercriminals behind Mailto ransomware actively try to convince victims that there is no way of recovering data in any other way, but you should not trust people who infected your PC with malware and are holding your files hostage.
Do not forget that, by paying the ransom, you also prove to them that their nefarious business model works, and it will only encourage the crooks to infect more victims. Unfortunately, some victims might not have another choice but paying to retrieve data that is vital for them.
Due to its popularity, ransomware viruses became a real threat to regular users and corporations worldwide. Therefore, you should take precautionary measures in order to make sure either swift recovery or prevention of the infection. Here are some tips from industry experts that want to avoid infections like NetWalker:
- Employ comprehensive anti-malware software that would be able to stop the incoming threats;
- Always update your operating system along with all the installed applications (set the update option to automatic);
- Avoid visiting high-risk sites, such as porn, torrent, gambling, etc.;
- Never open an attachment from a spam email that asks you to enable macros;
- Do not download pirated software or cracks;
- Use ad-blocker;
- Use strong passwords for all your accounts;
- Backup your files on a regular basis.
From our report of Feb 2020 · not reviewed since
Ways ransomware infection spreads
Unfortunately, ransomware trend among cybercriminals is only increasing, and, although the number of new ransomware strings released is in decline, the new variants of already existing file locking viruses keep emerging every day. The reason for that being is the fact that ransomware is now a lucrative business the attackers benefit from greatly, even if just a small fraction of users actually agree to pay the ransom.
It is yet unknown how particular ransomware is distributed by the threat actors because there are many different samples and campaigns that may get used. However, hackers usually use one or a few of the following methods:
The best tip should be to pay close attention to all the online content and activities that start on your machine. Take into consideration that criminals can inject malware into email attachments and websites that you visit, so malicious payload drop might not be easily noticed.
- Exploits;
- Spam emails;
- Cracks;
- Pirated software installers;
- Fake updates;
- Unprotected Remote Desktop connections;
- Malicious ads, etc.
The Mailto ransomware note
Hi!
Your files are encrypted.
All encrypted files for this computer has extension:
--
If for some reason you read this text before the encryption ended,
this can be understood by the fact that the computer slows down,
and your heart rate has increased due to the ability to turn it off,
then we recommend that you move away from the computer and accept that you have been compromised,
rebooting/shutdown will cause you to lose files without the possibility of recovery and even god will not be able to help you,
it could be files on the network belonging to other users, sure you want to take that responsibility?
--
Our encryption algorithms are very strong and your files are very well protected, you can't hope to recover them without our help.
The only way to get your files back is to cooperate with us and get the decrypter program.
Do not try to recover your files without a decrypt program, you may damage them and then they will be impossible to recover.
We advise you to contact us as soon as possible, otherwise there is a possibility that your files will never be returned.
For us this is just business and to prove to you our seriousness, we will decrypt you some files for free,
but we will not wait for your letter for a long time, mail can be abused, we are moving on, hurry up with the decision.
Сontact us:
1.sevenoneone@cock.li
2.kavariusing@tutanota.com
Don't forget to include your code in the email:
How to remove Mailto 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 Mailto 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 Mailto 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
.1be018and the instructions are inReadme.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.
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 Mailto 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 Mailto 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 Mailto 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.
From our report of Feb 2020 · not reviewed since
Remove NetWalker/Mailto ransomware and do not pay the attackers
To remove Mailto ransomware, you will have to employ anti-malware software that can detect and delete all the malicious files and components of the virus.
In some cases, however, the malware might interfere with the software when trying to delete the infection.
Only once you complete Mailto ransomware removal, you can connect your backup device or copy the data from the online storage. If you had no backups ready, please check for alternative methods below - they might help you get at least some portion of your data back.
Remember to choose reliable tools for NetWalker virus termination, so you can avoid additional damage and cyber threats that may end up on the system when you skip through crucial steps or ignore red flags. Security and system applications should be used to clean the machine and fix the damage this virus has caused: , , or .
[GI=method-1]To enter Safe Mode with Networking, please follow the following instructions:
[GI=method-2]You can also use System Restore to terminate the malicious payload of Mailto ransomware:
Data Recovery software does not work the same way decryptors work, as it retrieves the copy of the locked file from the depths of the hard drive. If that storage space was already overwritten, the data kept there will no longer be possible.
Make use of Windows Previous versions feature
This option is only available if you had System Restore enabled before the infection of the computer. Additionally, only one file can be recovered at the time, so the process might be very time-consuming.
ShadowExplorer might be employed to recover data locked by Mailto virus
ShadowExplorer can be useful if the malware fails to delete Shadow Volume Copies.
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.
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 Mailto 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 .1be018 and no longer open.
Setting it up step by step: 3-2-1 backups on Windows 11 and 10.
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 Mailto ransomware
Is there a decryptor for .1be018 files?
That depends on the family behind the .1be018 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 .1be018 files?
You cannot open them by renaming or by choosing another program. The .1be018 ending shows that Mailto 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 Mailto ransomware. Store the encrypted files on an external disk until then.
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 Mailto ransomware get on my computer?
The way Mailto 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 .1be018 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.
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.
Did Mailto ransomware steal my files or passwords?
We do not know yet. Nothing published so far shows data theft by Mailto ransomware, but the only confirmed sign is files that end in .1be018 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 Mailto 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 Readme.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. Readme.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 .1be018 attack?
Reinstalling removes the ransomware but not the encryption: your files ending in .1be018 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 Mailto 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 Mailto 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
- ITnews: Toll Group hit by "new variant" of Mailto ransomware (read October 6, 2026)
- Twitter: NEW Unknown #Ransomware (read October 6, 2026)
- Virus Total: 8c6d6a3ed7.exe detection rate (read October 6, 2026)
- WeLiveSecurity: Exploits: What are they and how do they work? (read October 6, 2026)
- CISA: StopRansomware (read October 6, 2026)