Mailto ransomware removal instructions

What is Mailto?

Discovered by GrujaRS, Mailto (also known as NetWalker) is malicious software and an updated version of Kokoklock ransomware. Mailto encrypts files, thereby rendering them unusable. The program encrypts data and renames files with the developer's email address and an extension comprising the victim's unique ID (e.g. ".e85fb1").

For example "1.jpg" might be renamed to "1.jpg.mailto[Hamlampampom@cock.li].e85fb1". Once the encryption is complete, Mailto stores a text file in the format "victim's_ID-Readme.txt" (e.g. "E85FB1-Readme.txt") on the desktop.

Screenshot of files encrypted by Mailto (random extension):

Ransom note overview

The message within the text file informs users that their data was encrypted. To restore it, they are urged to contact the cyber criminals responsible for encryption. Victims are encouraged to contact Mailto's developers via the email addresses provided - this will enable them to learn how to decrypt their files and/or pay the ransom.

Each victim with files infected by this ransomware receives a unique ID/personal code detailed within the text file. This code must be included in the email response. Additionally, users are permitted to attach one file free of charge for decryption. Generally, only cyber criminals can decrypt data compromised by their software.

Mailto and similar programs use strong encryptions that are virtually impossible to 'crack'. Note that cyber criminals can never be trusted - they often provide no decryption software/tools even if paid. If ransom demands are met, victims receive nothing in return and data is lost. The only way to recover encrypted files is from a backup, if one was created prior to encryption.

Ransomware in general

Mailto is similar to StuardRitchi, Caleb, Sherminator, and many other ransomware-type programs. All encrypt data and demand ransom payments to decrypt files. Differences are cryptographic algorithm used (symmetric or asymmetric) and size of ransom (commonly between three and four digit sums).

In most cases, manual decryption (without the involvement of cyber criminals) is impossible unless the ransomware is still in development and/or has flaws/bugs. To ensure data safety, keep backup copies on remote servers and/or unplugged storage devices. As these are also liable to damage, store multiple backups in different locations.

How did ransomware infect my computer?

Ransomware and other malware is proliferated in multiple ways: through trojans, spam campaigns, untrustworthy download channels, software "cracking" (activation) tools and fake updaters. Trojans are malicious programs designed to cause chain infections. They perform rogue download/installation of other malware.

Malicious content is also spread through various email attachments (e.g. executable and archive files, Microsoft Office and PDF documents, JavaScript and others). These deceptive emails are sent through large-scale spam campaigns and are often marked as "important" or "official".

Untrustworthy download sources also spread malware. These include, Peer-to-Peer sharing networks (e.g. BitTorrent, Gnutella, eMule and etc.), free file hosting websites, third party downloaders and other similar sources. Program "cracking" tools often install malware, rather than activating licensed software.

Fake updaters operate in a similar way - rather than updating programs, they exploit bugs/flaws and install malicious content.

How to protect yourself from ransomware infections

Attachments included in emails received from suspicious/unknown senders should never be opened. These emails are often disguised as "official", "important", "urgent", or otherwise highlighted as priority mail. In fact, irrelevant emails should not be opened, despite these misleading labels.

Download software from official and verified sources only. Avoid unofficial and untrustworthy download websites, Peer-to-Peer sharing networks and other third party downloaders. Software present on the system should be kept up-to-date via functions/tools provided by the official developer.

The same extends to software activation. Illegal activation tools ("cracks") might cause system infections. Have a reputable anti-virus/anti-spyware suite installed and updated.

These programs can be used to perform regular system scans for detection and elimination of potential threats. If your computer is already infected with Mailto, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.

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

Text presented in Mailto ransomware text file ("victim's_ID-Readme.txt"):

+++++++++++++++++++++++
---
What happen ?
---

Your files are encrypted, and currently unavailable.
You can check it: all files on your computer has expansion e85fb1.
By the way, everything is possible to recover, but you need to follow our instructions.
Otherwise, you cant return your data.

---
What guarantees?
---

Its just a business. We absolutely do not care about you and your deals, except getting
benefits. If we do not do our work and liabilities - nobody will not cooperate with us.
Its not in our interests.
To check the ability of returning files, you should write to us by email.
There you can decrypt one file for free. That is our guarantee.

---
How to contact with us ?
---

Email us:
1.Hamlampampom@cock.li
2.Galgalgalhalk@tutanota.com

sevenoneone@cock.li
kavariusing@tutanota.com

kkeessnnkkaa@cock.li
hhaaxxhhaaxx@tuta.io

knoocknoo@cock.li
eeeooppaaaxxx@tuta.io

Be sure to include your personal code in the letter:
-

Update 6 February 2020 - Developers of Mailto (NetWalker) ransomware have recently started targeting various enterprise networks in order to generate large revenues. Companies are likely to have more valuable files and data than regular users.

In addition, these files often contain sensitive data (e.g., customers' personal data, product information [such as patents, ingredients, and similar), information about employees, etc.) Therefore, companies are much more likely to consider paying for decryption, and thus blackmailing becomes easier for the criminals.

Furthermore, companies are likely to pay more than say a home user looking to retrieve a music collection, photos, and so on. This type of personal information has limited value and thus criminals are more likely to generate revenue by blackmailing companies rather than home users.

Additionally, an updated version of Mailto ransomware has been released, although its behavior is virtually identical. The only differences are email addresses provided and details within the ransom message.

Screenshot of the updated Mailto ransomware message ("random_string-Readme.txt"):

Text presented within this file:

Hi!
Your files are encrypted.
All encrypted files for this computer has extension: .f5be7

--

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:
-

Screenshot of files encrypted by the updated Mailto ransomware (random extension remains):

Screenshot of the updated Mailto ransomware process (disguised as "Sticky Password") in Windows Task Manager:

Update 12 March 2020 - Criminals have released yet another variant of Mailto (NetWalker) ransomware. The filenames are now appended with a random extension and the ransom message ("[[random_string]-Readme.txt") is also slightly different.

Screenshot of updated Mailto (NetWalker) ransomware ransom message:

Text presented within this file:

Hi!
Your files are encrypted.
All encrypted files for this computer has extension: .8fec81

--
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.

--
Our  encryption algorithms are very strong and your files are very well protected,
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 decrypter program, you may damage them and then they will be impossible to recover.

For us this is just business and to prove to you our seriousness, we will decrypt you one file for free.
Just open our website, upload the encrypted file and get the decrypted file for free.

--

Steps to get access on our website:
1.Download and install tor-browser: hxxps://torproject.org/
2.Open our website: rnfdsgm6wb6j6su5txkekw4u4y47kp2eatvu7d6xhyn5cs4lt4pdrqqd.onion
3.Put your personal code in the input form:
-

Screenshot of files encrypted by this ransomware (random extension):

Appearance of the updated Mailto (NetWalker) ransomware Tor website (GIF):

Text presented within this site:

"Payment" tab:

 

Your files are encrypted.
Only way to decrypt your files, is buy the decrypter program.
Your user key: 30CAB775, write it down and use it to log in again.
Invoice for payment
You have left 9 days 23 hours 59 minutes 36 seconds
Status: Waiting for payment
You can buy the decrypter program for your computer(s).
The amount before the increase is 2000$ (0.21740000 BTC).
If there is no payment before 22.03.20 [05:01], the price will increase by x2 times and will be 4000$ (0.43480000 BTC)
Decrypter for: COMPUTER(S): code_8fec81
-
Amount for payment: 0.21740000 BTC
You payed: 0.00000000 BTC

 

"Free decrypt" tab:

For test we can upload and decrypt 3 images or document files free
File must be less than 3 megabyte.
Allow formats: .jpg, jpeg, .png, .bmp, .doc, .docx

Choose a file or drag it here

 

 

"FAQ" tab:

 

1. Where to buy bitcoin?
    1) The fastest and most reliable way is to use the help of Cyber Security IT company, they will be able to solve all questions for you.
    2) Buy bitcoins with cash, use google to search for sellers.
         You will need a bitcoin wallet, we recommend using it: hxxps://login.blockchain.com/#/signup
    3) The slowest way is to buy bitcoin on the exchange. The exchange requires verification, this process may take several days.
         List of exchanges:
           1) hxxps://localbitcoins.com
           2) hxxps://blockchain.com
           3) hxxps://www.coindesk.com
           4) Other exchange.

2. How long after payment will I be able to get the decrypter program?
    You will be able to download the decrypter program as soon as Your transaction has more 3 of confirmations.
    This usually takes between 30 minutes and 3 hours.
    (Depending on the size of the commission. Never specify a zero сommission, use an average/high сommission.)

3. I sent a message to the chat, how long to wait for a response?
    The average response time to messages is 2 hours.
    The maximum response time is 12 hours.

4. How can I make sure that you can decrypt my files?
    When you log in, your user code or user key is checked and your keys are searched.
    If you are logged in, your keys are found.
    To make sure, you can decrypt 3 of photos (images) and document files for free in the "free decrypt" section

5. How can I make sure That you will give me the decrypter program after payment?
    It's just business. We value our name, so after payment you are guaranteed to get the decrypter program.

6. How long does it take to decrypt files?
   Decryption of files is a very fast process, it all depends on the number of encrypted files, as well as their location HDD/Network.

7. What if I can 't decrypt my files after receiving the decrypter program?
    This is excluded, Your files will be 100% decrypted.
    After payment, you will receive instructions for decryption along with the decrypter program.
    We will answer any questions about decrypting files in the chat.
    Along with the decrypt program, you get technical support.

Update 23 March 2020 - Cyber criminals have recently started a Coronavirus-related email spam campaign to spread Mailto (NetWalker) ransomware.

Update 27 March 2020 - A week ago, cyber criminals started an affiliate campaign to provide Mailto (NetWalker) as Ransomware as a Service (RaaS). Therefore, anyone can cooperate with the ransomware developers to earn revenue. Cyber criminals provide all of the necessary infection tools, while the affiliate must take care of spreading the ransomware.

It is currently unconfirmed whether developers ask for a subscription/one-time payment or a percentage of the profit that the affiliate makes. The RaaS is promoted on various hacker forums.

Example of a forum post used to promote Mailto (NetWalker) as RaaS (the original text is in Russian and the example is translated):

Update May 15, 2020 - The developers of NetWalker ransomware have recently started leaking data stolen from their victims. The data is available in their website blog and only those victims who have not agreed to pay ransoms get their data leaked.

Moreover, developers mostly leak information stolen from various companies, businesses, etc., because they have way more resources than a regular home user and thus may eventually agree to pay in exchange for data deletion and removal from the website.

Screenshot of NetWalker ransomware's data leaking blog:

Mailto ransomware removal:

Instant automatic malware removal:

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Removal and file recovery procedure

If your files are encrypted with a new extension and a ransom note has appeared, you've been hit by ransomware. Don't pay. The procedure below works in order: contain the infection, identify the variant, remove the ransomware itself (so anything you restore doesn't get re-encrypted), and try to recover files using free decryption tools, Windows Volume Shadow Copies, or backups. Run a full system scan with Combo Cleaner to remove the infection - then move on to file recovery.

Common ransomware behaviors

VisibleEncrypts your files and renames them

The ransomware reads each file, encrypts the contents with the attacker's public key, and writes the encrypted bytes back to disk. Most variants also rename the file by appending a new extension - .net, .locked, .crypt, .lockbit, .djvu, etc. Without the matching private key, the encrypted files cannot be opened normally. Recovery depends on a free decryption tool, a recoverable Volume Shadow Copy, or a clean backup.

VisibleDrops a ransom note in every encrypted folder

A text or HTML file (usually named HOW_TO_DECRYPT.txt, README.txt, _readme.txt, or similar) is placed in every folder that contains encrypted files. The note explains the situation, lists a payment amount in cryptocurrency, gives a deadline, and provides a contact email or .onion site. Save the note - don't delete it. Its exact wording, the email address, and the bitcoin wallet are how you identify the variant in the next phase.

VisibleReplaces the desktop wallpaper

Many ransomware variants change the Windows wallpaper to a black or red image with the ransom message and instructions. The wallpaper is just a visual scare tactic - it doesn't add any actual capability and reverts to normal once the ransomware is removed. Photograph it before removal in case the contact details are useful for variant identification or for reporting to authorities.

HiddenDeletes Volume Shadow Copies

One of the first things modern ransomware does after launching is run vssadmin delete shadows /all /quiet to wipe Windows' built-in Volume Shadow Copies - the snapshots that Previous Versions and System Restore rely on. Some ransomware doesn't fully succeed (especially on systems where the user lacks full admin rights), leaving partial shadow copies recoverable. Phase 4 step 11 covers how to check what survived.

HiddenDisables Windows Defender and other security tools

Before encrypting, the ransomware tries to silence anything that could alert you or block it - Windows Defender real-time protection, third-party antivirus services, backup agents (Veeam, Acronis), and sometimes the Windows Event Log service. It often modifies Group Policy or registry keys to keep these off after reboot. Phase 3 step 9 explicitly turns Tamper Protection back on so the next ransomware attempt can't repeat the trick.

HiddenSpreads laterally to other PCs on the network

Network-aware ransomware (LockBit, Conti, BlackCat, Akira families) doesn't stop at the first machine. It scans for SMB shares, mapped drives, and other PCs on the same network, then encrypts whatever it can reach. On Windows domains, a single compromised user with admin rights can lead to all-domain encryption. This is why Phase 1 step 2 disconnects the network as the very first action - it stops the spread immediately.

HiddenSteals data before encrypting (double extortion)

Modern ransomware (LockBit, BlackCat / ALPHV, Akira, Cl0p, Royal) almost always exfiltrates data before encrypting. The attacker then runs a "double extortion" play: pay the ransom for decryption, plus pay again to prevent the stolen data from being leaked on the group's leak site. Paying the first ransom does not get the leaked data back - assume that anything the ransomware could read was uploaded. This is one more reason not to pay: the data is already out.

Tools you'll need

Combo Cleaner Antivirus 7-days free trial

Recommended primary scanner. VB100 certified. Removes the ransomware infection so file recovery doesn't get re-encrypted.

Microsoft Defender Offline Free · built-in

Built into Windows. Scans before Windows fully loads to catch persistence the running scanners miss.

Microsoft Safety Scanner (MSERT) Free

Microsoft's free on-demand scanner. Always-current signatures - the binary expires every 10 days.

ID Ransomware Free · web

Upload a ransom note and a sample encrypted file - identifies the variant family and tells you whether a free decryptor exists.

No More Ransom Project Free · web

Joint project of Europol, Dutch Police, and security vendors. Free decryption tools indexed by ransomware family.

Shadow Explorer Free

Browse Windows Volume Shadow Copies as a normal file tree - useful when ransomware partially failed to delete them.

Recuva Free

Deleted-file recovery. Long-shot for ransomware - only helps if the variant deleted unencrypted originals before encrypting copies.

Phase 1~ 5 min

Don't pay & contain

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1

Don't pay the ransom

1 min · read⚠ Do not skip

Paying the ransom does not guarantee you'll get your files back. Major ransomware response studies consistently show that a meaningful percentage of paying victims either receive a non-working decryptor, only partial decryption, or no decryptor at all. Beyond that:

• Paying confirms you as a willing target - re-attack rates within 12 months are high
• Several ransomware groups have been sanctioned (US OFAC, UK OFSI). Paying these groups may be illegal under sanctions law in your country
• The ransom funds the next attack - on you or someone else
• Modern ransomware almost always exfiltrates data first, so paying doesn't get the leaked data back. Assume anything the malware could read was uploaded
• Decryptors, even when they work, often leave files corrupted because the encryption itself was buggy or rushed

The path below tries every legal, free recovery option first. Pay only as an absolute last resort, after consulting a lawyer and your country's cyber crime authority.

2

Disconnect from the network and log out of cloud storage

2 minNo tool needed

Pull the Ethernet cable and turn off Wi-Fi on the affected PC. If multiple computers share the network, do the same on every machine you suspect could be affected, including any servers and NAS units.

Then sign out of cloud storage clients (OneDrive, Dropbox, Google Drive, iCloud) from their app settings. If you can, pause the sync. Some ransomware uses the running sync client to push encrypted versions over your clean cloud copies.

Why this matters

Modern ransomware spreads laterally across SMB shares, mapped drives, RDP, and reachable network neighbors. Disconnecting stops the spread the moment you do it. Logging out of cloud sync clients prevents the ransomware from encrypting the cloud copies of your files via the sync API.

3

Unplug external drives and USB storage

1 minNo tool needed

Safely eject any external drives, USB sticks, SD cards, and network-attached storage shares - then unplug them. If a drive was connected when the ransomware ran, the files on it may already be encrypted, but unplugging stops further damage.

Critically: don't reconnect any drive (including your most recent backup) to this PC until the ransomware is removed in Phase 3. Reconnecting an external backup to an actively-infected PC is the most common way that backup gets encrypted too.

Phase 2~ 5 min

Identify the variant

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4

Save the ransom note and a sample encrypted file

2 min

Copy the ransom note and one small encrypted file (under 1 MB) to a USB stick, or photograph the note with your phone. You'll need both for the variant identification step.

The ransom note is usually one of:

• A .txt file in every encrypted folder (typically HOW_TO_DECRYPT.txt, README.txt, or _readme.txt)
• An .html file with the same purpose
• A changed desktop wallpaper - photograph it
• A lock-screen interrupt that runs at startup - rarer

Important

Don't delete the note. Variant identification depends on its exact wording, the contact email, and the bitcoin wallet address. The note is also evidence if you report to authorities.

5

Identify the variant with ID Ransomware

Tool: ID Ransomware3 min

From a clean device (your phone is fine, or another PC that wasn't on the affected network), visit id-ransomware.malwarehunterteam.com. Upload the ransom note and the sample encrypted file. The site identifies the variant family and tells you whether a free decryptor exists.

Pro tip

ID Ransomware is run by the Malware Hunter Team. Files you upload are kept private - they're used for analysis, not published. If you're concerned about uploading data anyway, you can paste the contact email and bitcoin wallet from the note - those are often enough for identification.

Phase 3~ 30-45 min

Remove the ransomware

---

The ransomware itself must be removed before any file recovery. If it's still active, anything you restore in Phase 4 gets re-encrypted within minutes.

6

Boot to Safe Mode with Networking and download the scanners

5 min

Safe Mode loads only the minimal Windows drivers, which prevents most ransomware from auto-running while you set up the scanners.

Windows 11: open Settings → System → Recovery, click Restart now next to Advanced startup. After the restart, click Troubleshoot → Advanced options → Startup Settings → Restart, then press 5 or F5.

Windows 10: click the Windows logo, hold Shift, click the Power icon and choose Restart. From the Choose-an-option screen, click Troubleshoot → Advanced options → Startup Settings → Restart, then press F5.

Once Safe Mode has loaded, turn Wi-Fi back on and download Combo Cleaner (used in step 8) and Microsoft Safety Scanner (used in step 9). Save both installers to your Desktop, then disconnect Wi-Fi again before scanning.

7

Run Microsoft Defender Offline

Tool: Built into Windows15 min

Reboot to normal Windows. Open Windows Security → Virus & threat protection → Scan options. Select Microsoft Defender Antivirus (offline scan) and click Scan now. The PC restarts into a stripped-down environment and scans the disk before Windows fully loads.

Why this comes first

Some ransomware variants drop bootkit components or kernel hooks that hide from any scanner running on the same Windows session that's already infected. A pre-boot offline scan sees the disk before the malware can load itself.

Recommended antivirus

Combo Cleaner

VB100 certified. Includes anti-trojan, registry/persistence scanning, and anti-spyware in one pass. The 7-day free trial is available.

Download Combo Cleaner

8

Run a full Combo Cleaner scan

Tool: Combo Cleaner20-40 min

Run the installer you downloaded in step 6 and start a full system scan (not the quick scan). Let it complete, review what it detected, and apply the recommended actions. Combo Cleaner quarantines the ransomware executable and the registry / scheduled-task entries that re-launch it on reboot.

9

Run Microsoft Safety Scanner and re-enable Defender

Tool: MSERT15 min

Run Microsoft Safety Scanner (MSERT.exe) as a second-opinion full scan. The binary expires every 10 days so the copy you downloaded has the latest signatures.

Once it finishes, open Windows Security → Virus & threat protection → Manage settings and confirm Real-time protection, Cloud-delivered protection, and Tamper Protection are all on. Many ransomware variants disable Defender during the attack - this is where you switch it back on so the next attempt can't repeat the trick.

Why a second scan

Different scanning engines catch different threats. Running an additional Microsoft scan after Combo Cleaner is the most underused verification step in malware removal - and free.

Phase 4~ 30-60 min · results vary

Try to recover files

---

Try the steps in order. The first decryptor that works ends the recovery process - no need to do all four.

10

Check the No More Ransom Project for a free decryptor

Tool: nomoreransom.org★ Cleanest path if listed5 min

Visit nomoreransom.org and search the Decryption Tools list for the variant name returned by ID Ransomware. The project is run by Europol, the Dutch Police, and security vendors - everything listed is legitimate and free.

If a decryptor exists, download it onto a clean PC, copy it across, and follow its instructions exactly. Decryptors usually want you to point them at a sample encrypted file plus its known unencrypted version (sometimes any image you previously had a backup of works).

Free decryptors exist for parts of the STOP/Djvu, GandCrab, REvil, Avaddon, Conti and Hive families, among others. Most modern variants don't have public decryptors - if yours isn't listed, that's expected; move to the next step.

11

Try Windows Volume Shadow Copies

Tool: Shadow Explorer / vssadmin15 min

Windows automatically creates Volume Shadow Copies of files when System Restore points are made or scheduled backups run. Most ransomware tries to wipe these (vssadmin delete shadows /all /quiet), but the deletion sometimes fails partially - especially if the running user doesn't have full admin rights. When it does fail, snapshots survive that contain pre-encryption versions of your files.

First, check what's there. Open Command Prompt as Administrator and run:

vssadmin list shadows

If you see entries listed, shadow copies survived. To restore from them:

• Built-in: right-click any folder → Properties → Previous Versions tab. Pick a snapshot dated before the infection and restore.
• Better tool for browsing: install Shadow Explorer (free). It shows all snapshots as a normal file tree and lets you copy out only the files you want.

Why check this even when there's a decryptor

Shadow Copies recover the original files exactly, with no risk of decryption errors. If they survived, this is faster and cleaner than running a decryptor on the encrypted set.

12

Restore from cloud or external backup

Tool: your backup software30 min

If you have a backup that pre-dates the infection, this is the cleanest recovery available. Important precautions:

• Don't reconnect a backup drive until Phase 3 is complete. If the ransomware is still active, plugging in the backup encrypts it too.
• For cloud backups (OneDrive, Dropbox, Google Drive, iCloud), use the Version History feature to roll individual files back to pre-encryption versions.
• OneDrive specifically has a "Restore your OneDrive" feature: if it detected mass file changes, you can roll back the entire account up to 30 days. Sign in at OneDrive on the web, click the Settings gear, and choose Restore your OneDrive. Microsoft 365 subscribers also get ransomware detection alerts; non-subscribers get one free recovery.
• Verify the restored files open correctly before you delete the encrypted set. Test a few documents, photos, and any database / project files.

13

Try Recuva as a last-resort recovery

Tool: Recuva30 min

Recuva is a long shot, not a primary recovery tool. Most modern ransomware encrypts files in place - it reads the original, encrypts the data, and writes the encrypted bytes back to the same disk location. In that case, the original isn't deleted, just rewritten - and Recuva has nothing to find.

But for older or simpler variants that deleted originals before creating encrypted copies (rather than encrypting in place), Recuva can sometimes pull the originals from unallocated disk space. Worth trying as a last resort, especially before you use the disk much further.

If you try it:

• Stop using the disk as much as possible - every disk write reduces recovery odds
• Run Recuva from a USB stick, not from the affected disk
• Use Deep Scan mode (slower but the only mode worth running for this scenario)

Don't skip the steps above expecting Recuva to bail you out. It works in maybe 5-20% of cases, depending on the variant and how soon you try.

Phase 5~ 20 min + ongoing

Report & prevent re-infection

---

14

Report the attack to authorities

10-20 min

Even if your files aren't recovered, your report helps authorities track variants, attribute groups, and warn future victims. In some jurisdictions (especially the US and UK) early reporting can sometimes help recall a wired ransom payment via banking partners.

United States: ic3.gov (FBI) + stopransomware.gov (CISA)

United Kingdom: reportfraud.police.uk (Report Fraud, the successor to Action Fraud) + NCSC

Canada: antifraudcentre.ca

Australia: ReportCyber

Spain: Policía Nacional (Oficina Virtual de Denuncias)

France: cybermalveillance.gouv.fr

Germany: BKA

Italy: Polizia Postale

Netherlands: Politie

Poland: CERT Polska

Portugal: CNCS

EU (other): your national CERT

Save the report number - banks, insurers, and credit bureaus will ask for it. If you operate a business, you may also have legal disclosure obligations (GDPR in the EU, state breach laws in the US) that run on a 72-hour clock.

15

Plan 3-2-1 backups going forward

30 min initial

The single best defense against ransomware is a tested backup. Use the 3-2-1 rule:

• 3 copies of your data
• 2 different storage media (e.g., internal drive + external drive)
• 1 offline / air-gapped copy (an external drive that isn't always connected)

Recommended cadence:

• Daily: cloud sync (OneDrive, Dropbox, Google Drive) - convenient, but vulnerable if the ransomware reaches the sync folder. The Version History feature is what saves you
• Weekly: external drive that you connect briefly, then disconnect - the air-gap is what protects against ransomware
• Monthly: a second external drive stored off-site (different physical location) - protects against fire, theft, flood

Important

Test the backup at least once. Open a few files from it, check sizes match, restore one to a different folder. An untested backup isn't a backup - it's a hope.

16

Patch the entry point and monitor for 30 days

5 min/day · 30 days

Most reinfections happen via the same vector that worked the first time. Until you've patched the entry point, watch for:

• Unusual disk activity, unexpected file modifications, or unfamiliar processes in Task Manager
• Unexpected reboots or new accounts you didn't create
• Defender or your antivirus turning itself off again

Common entry vectors and what to do about each:

• Phishing email with a malicious attachment - review email filters and train yourself / staff to recognise the patterns - see pcrisk's Phishing/Scam reference
• Exposed RDP with weak passwords - disable Remote Desktop from Settings → System → Remote Desktop if you don't need it. If you do, put it behind a VPN and require a long password plus MFA
• Unpatched VPN appliances or public-facing apps - check the vendor's advisories page and apply the latest firmware
• Cracked / pirated software - was the most common vector for STOP/Djvu in particular. Don't run software from torrent sites

Run a Combo Cleaner scan weekly for the first month. Update Windows, browsers, and applications aggressively.

Important: Removing a ransomware infection requires a full system scan, not a manual file delete. If you're not confident with the manual procedure, run an automated scan with Combo Cleaner and Windows Defender and stop there - that combination removes the vast majority of consumer ransomware variants. Then move to Phase 4 for file recovery, or to Phase 5 if your files are unrecoverable and you need to start fresh from a clean Windows install.

Frequently Asked Questions (FAQ)

How was my computer hacked and how did hackers encrypt my files?

Ransomware is disseminated through deceptive email attachments or links, infected software downloads (e.g., pirated software or cracking tools), vulnerabilities in outdated software and operating systems, malicious ads, infected USB drives, P2P networks, and similar channels. Typically, computers become infected when users activate ransomware by themselves.

How to open encrypted files?

To open encrypted files, victims typically need the decryption key. It is impossible to open files while they are encrypted.

Where should I look for free decryption tools for Mailto ransomware?

In case of a ransomware attack you should check the No More Ransom project website (more information above).

I can pay you a lot of money, can you decrypt files for me?

Unfortunately, we do not offer this service. Decrypting files encrypted by ransomware usually requires intervention from developers unless there is a flaw in the ransomware. Therefore, third parties claiming to offer paid decryption are likely acting as intermediaries or attempting to scam you.

Will Combo Cleaner help me remove Mailto ransomware?

Combo Cleaner is equipped to conduct a thorough scan of your computer and eradicate ransomware. It is crucial to understand that while utilizing an antivirus program serves as an initial step in recovery, security software lacks the capability to decipher the encrypted files.