Remove Leto ransomware from the operating system

Also Known As: Leto virus
Distribution: Moderate
Damage level: Severe

Leto ransomware removal instructions

What is Leto?

Leto is malicious software, belonging to the Djvu ransomware family. It operates by encrypting data and keeping it locked until a ransom is paid (i.e., decryption software/tool and a unique key are purchased). As Leto encrypts, it renames all files by adding the ".leto extension. For example, a file named "1.jpg" will appear as "1.jpg.leto", and so on. After the process is complete, a text file called "_readme.txt" is stored on the desktop.

The message within the text file informs affected users that their files have been encrypted with the strongest encryption and a unique key (individually generated for each victim). It states that the only way recover the data is to purchase the decryptor and key from the developers of Leto. The victims are encouraged to contact them via the email addresses provided. If contact is made within 72 hours, the cost is reduced by fifty percent. The size of ransom (should users fail to contact them within the time-frame given) is 980 USD. As 'proof' of their ability to restore the data, the cyber criminals offer to decrypt one file free of charge, provided it does not contain "valuable information" (implying that it cannot be a backup, database, large excel sheet, or similar). If a response is not received within six hours, victims are instructed to check their email "Junk/Spam" folder for it. These cyber criminals claim that only they are capable of decrypting the data. Unfortunately, this information is accurate. There are no free tools available that can break Leto encryption. Most ransomware programs use strong encryptions, which cannot be "cracked" without the involvement of the developers, however, it is strongly advised against contacting or paying any cyber criminals. Despite meeting the ransom demands, users often do not receive any of the promised tools/keys. Therefore, their data remains encrypted and permanently lost. The only viable solution is restoring files from a backup, provided one was made prior to the ransomware infection and was stored separately.

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

Leto decrypt instructions

CASHEstemani, and Bora are other examples of malicious programs similar to Leto. Most ransomware encrypts data and demands ransoms to be paid. The cryptographic algorithm they use (symmetric or asymmetric) and size of the ransom, however, can vary from one ransomware infection to the other. Usually, ransom sizes range between three-digit and four-digit sums (in USD). Digital currencies (e.g. cryptocurrencies, pre-paid vouchers, etc.) are preferred by cyber criminals, as these transactions are difficult/impossible to trace. Unless the ransomware is still in development and/or has flaws/bugs, manual decryption is impossible. To ensure data safety, keep backup copies on remote servers and/or unplugged storage devices. Since these systems/devices are liable to damage, it is best to store multiple backups in different locations.

How did ransomware infect my computer?

Ransomware and other malware is mostly proliferated via trojans, spam email campaigns, untrustworthy download sources, software "cracking" (activation) tools, and fake updaters. Trojans are malicious programs designed to cause chain infections (i.e., download/install additional malware). Massive scale spam campaigns are used to send thousands of emails containing malicious attachments (or web-links leading to them). These deceptive emails are typically marked as "official", "important", "urgent", or otherwise highlighted as priority mail. The attachments found in emails of this type can be in various file formats (e.g. archive and executable files, Microsoft Office and PDF documents, JavaScript, etc.). Once these files are opened (run, executed, etc.), they cause the infection by downloading/installing malicious programs. P2P sharing networks (BitTorrent, eMule, Gnutella, etc.), unofficial and free file-hosting websites, third party downloaders, and similar sources, are untrustworthy. Therefore, they might offer infectious content. Software "cracking" tools can download/install malware, rather than activating licensed products. Fake updaters exploit weaknesses in outdated programs and/or download/install malicious software, rather than the updates.

Threat Summary:
Name Leto virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .leto
Ransom Demanding Message _readme.txt
Ransom Amount $490/$980
Cyber Criminal Contact,
Detection Names AVG (FileRepMalware), BitDefender (Trojan.GenericKD.41896992), ESET-NOD32 (A Variant Of Win32/Kryptik.GXHV), Kaspersky (Trojan-Ransom.Win32.Stop.eo), Full List Of Detections (VirusTotal)
Symptoms Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.
Additional Information This malware is designed to show a fake Windows Update window and modify the Windows "hosts" file to prevent users from accessing cyber security websites (more information below).
Distribution methods Infected email attachments (macros), torrent websites, malicious ads, unofficial activation and updating tools.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password-stealing trojans and malware infections can be installed together with a ransomware infection.
Malware Removal (Windows)

To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Malwarebytes.
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To use full-featured product, you have to purchase a license for Malwarebytes. 14 days free trial available.

How to protect yourself from ransomware infections?

Do not open irrelevant and/or suspicious emails, especially those received from unknown senders (addresses). File attachments (or web-links) found in such emails should never be opened, as they cause the infections. Use only official and verified download sources. Installed software should be kept updated via functions/tools provided by the official developers only. The same extends to software activation - illegal activation tools ("cracks") must not be used, as they can install malware. Have a reputable anti-virus or anti-spyware suite installed. This software should be kept up-to-data and used to perform regular system scans and threat removals. If your computer is already infected with Leto, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.

Text presented in Leto ransomware text file ("_readme.txt"):


Don't worry, you can return all your files!
All your files like photos, databases, documents and other important are encrypted with
strongest encryption and unique key.
The only method of recovering files is to purchase decrypt tool and unique key for you.
This software will decrypt all your encrypted files.
What guarantees you have?
You can send one of your encrypted file from your PC and we decrypt it for free.
But we can decrypt only 1 file for free. File must not contain valuable information.
You can get and look video overview decrypt tool:
Price of private key and decrypt software is $980.
Discount 50% available if you contact us first 72 hours, that's price for you is $490.
Please note that you'll never restore your data without payment.
Check your e-mail "Spam" or "Junk" folder if you don't get answer more than 6 hours.

To get this software you need write on our e-mail:

Reserve e-mail address to contact us:

Your personal ID:

Screenshot of files encrypted by Leto (".leto" extension):

Files encrypted by Leto

Screenshot of fake Windows update pop-up displayed during the encryption:

Fake Windows pop-up displayed by Leto during the encryption

IMPORTANT NOTE! - As well as encrypting data, ransomware-type infections from the Djvu malware family also add a number of entries to the Windows "hosts" file. The entries contain URLs of various websites, most of which are related to malware removal. This is done to prevent users from accessing malware security websites and seeking help. Our website ( is also on the list. Removing these entries, however, is simple - you can find detailed instructions in this article (note that, although the steps are shown in the Windows 10 environment, the process is virtually identical on all versions of the Microsoft Windows operating system).

Screenshot of websites added to Windows hosts file:

Tro Ransomware adding websites to Windows Hosts file

There are currently two versions of Djvu ransomware infections: old and new. The old versions were designed to encrypt data by using a hard-coded "offline key" whenever the infected machine had no internet connection or the server was timing out/not responding. Therefore, some victims were able to decrypt data using a tool developed by cyber security researcher, Michael Gillespie, however, since the encryption mechanism has been slightly changed (hence the new version), the decrypter no longer works. If your data has been encrypted by an older version, you might be able to restore it with the aforementioned tool (download link). It supports a total of 134 file extensions and you can find the entire list in the "About" screen.

Screenshot of STOP/Djvu decrypter by Michael Gillespie:

STOP/Djvu ransomware decrypter by Michael Gillespie

Leto ransomware removal:

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Malwarebytes is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the Leto virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the Leto ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining Leto ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of Leto are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by Leto, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as Leto ransomware.

Note that Windows 10 Fall Creators Update includes a "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default, this feature automatically protects files stored in the Documents, Pictures, Videos, Music, Favorites, and Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here is more information on how to get this update and add an additional protection layer from ransomware infections.

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove Leto ransomware:

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

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Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

QR Code
Leto virus QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of Leto virus on your mobile device.
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