How to remove Usam ransomware?

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

Usam ransomware removal instructions

What is Usam?

Usam is one of the malicious programs that belong to the ransomware family called Djvu, this particular ransomware was discovered by Michael Gillespie. Typically, malware of this type encrypts files, modifies their filenames and creates and/or displays some ransom note. Usam renames encrypted files by appending the ".usam" extension to their filenames. For instance, it renames "1.jpg" to "1.jpg.usam", "2.jpg" to "2.jpg.usam", and so forth. It creates "_readme.txt" text file, a ransom note which contains details such as size of a ransom, email address which supposed to be used to contact Usam's developers, etc.

Victims are informed that Usam has encrypted photos, databases, documents and other data with the strongest encryption algorithm and unique key. The only way to recover (decrypt) files is to use a certain decryption tool and unique key that can be purchased from cyber criminals behind Usam. As explained in the ransom note, those tools can be purchased either for $980 or $490, their price depends on how fast victims will write an email to address. As a proof that Usam's developers can help their victims to decrypt encrypted files they offer to decrypt one file for free, victims can send it to he aforementioned email address. Although, even if they have the right decryption tools, it does not mean that they will send them - quite often victims who pay a ransom get scammed (they do not receive any decryption tools even after a transaction/payment). Therefore, it is strongly recommended not to trust neither cyber criminals behind Usam or any other ransomware. Unfortunately, most of the times there are no third party tools that could decrypt files encrypted by a certain ransomware. Usually victims have the only free option - to restore files from a backup. Additionally, it is possible to prevent installed ransomware from causing further encryptions by uninstalling it. Although, files that are already encrypted remain inaccessible even after its uninstallation.

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

Usam decrypt instructions (_readme.txt)

To sum up, all ransomware-type programs are more or less the same: they encrypt files and provide victims with instructions on how to contact cyber criminals, pay a ransom and/or some other details. Some more examples of ransomware are R3f5s, Yogynicof and Bad. Usually there are two main differences between such malware: price of a decryption software and/or key and encryption algorithm (symmetric or asymmetric) that it uses to encrypt data. As mentioned in the previous paragraph, in most cases it is impossible to decrypt files encrypted by ransomware without tools that only its developers have. It is possible only when ransomware has some vulnerabilities/it is not fully developed. The problem is that it does not happen often and victims can recover their files for free only when they have a data backup. Therefore, it is recommended to always have one and keep it stored on a remote server and/or unplugged storage device.

How did ransomware infect my computer?

Typically, users get tricked into installing ransomware (or other malware) through spam campaigns, unreliable file and software download channels, fake software updating tools, unofficial software activators ('cracking' tools) and Trojans. In the first it happens when cyber criminals send emails that contain malicious attachments and recipients open/execute them. Typically, cyber criminals attach malicious Microsoft Office documents, executable files (like .exe), JavaScript files, archives like ZIP, RAR or PDF documents. Also, they often send emails containing some malicious website links that are designed to download malicious files. Another way to get tricked into installing malicious software is to download files, programs through various questionable file and software download channels. For example, Peer-to-Peer networks (like torrent clients, eMule), unofficial websites, free file hosting or freeware download pages and third party downloaders. Cyber criminals often use them to distribute malware. They succeed when users execute downloaded malicious files that are designed to install some malicious program. Fake software updaters infect systems by installing malicious software instead of updating or fixing installed one. Also, such updaters can be designed to cause such damage by exploiting bugs, flaws of outdated software. Software 'cracking' tools are programs that supposed to illegally activate software for free. Although, very often such tools are designed to proliferate malware and users who use them to bypass paid activation infect their computers with some high-risk malware. Trojans are malicious program that can be designed to cause additional damage. However, they need to be already installed. When users unknowingly install such malware, then it causes chain infection by installing some other malicious software.

Threat Summary:
Name Usam virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .usam
Ransom Demanding Message _readme.txt
Ransom Amount $980/$490
Cyber Criminal Contact
Detection Names AVG (FileRepMalware), BitDefender (Gen:Variant.Ser.Ulise.256), ESET-NOD32 (A Variant Of Win32/Kryptik.HEBU), Kaspersky (UDS:DangerousObject.Multi.Generic), 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)

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How to protect yourself from ransomware infections?

Software and files should never be downloaded from unofficial pages or other channels like third party downloaders, Peer-to-Peer networks (e.g., torrent clients, eMule), freeware download pages, etc. Third party installers should never be used too. The safest way to download files, programs is by using official websites and direct links. Attachments and website links in irrelevant emails should not be trusted (opened), especially when such emails are received from unknown, suspicious addresses. Installed software must be updated and activated only with tools and/or functions that are designed/provided by official software developers. Unofficial, third party activators, updaters often are be designed to install malware. Also, it is not legal to activate licensed programs with unofficial activation ('cracking') tools. And finally, a computer should be regularly scanned for threats with a reputable antivirus or anti-spyware software, it is important to keep such software up-to-date. If your computer is already infected with Usam, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.

Text presented in Usam ransomware's 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:

Your personal ID:

Screenshot of files encrypted by Usam (".usam" extension):

Files encrypted by Usam ransomware (.usam extension)

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

Fake Windows pop-up displayed by Usam 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, released in August, 2019), the decrypter no longer works and it is not supported anymore. If your data has been encrypted by an older version, you might be able to restore it with the another tool developed by Emsisoft and Michael Gillespie. It supports a total of 148 Djvu's variants and you can find more information, as well as download link and decryption instructions in Emsisoft's official page.

Screenshot of Djvu decryption tool by Emsisoft and Michael Gillespie:

Djvu ransomware decrypter by Michael Gillespie and Emsisoft

Additionally, Emsisoft is now providing a service that allows to decrypt data (again, only if it was encrypted by Djvu variants released before August, 2019) for those victims who have a pair of the same file before and after the encryption. All victims have to do is upload a pair of original and encrypted file to Emsisoft's Djvu decryption page and download the aforementioned decryption tool (the download link will be provided after uploading files). Note that the file processing may take some time so be patient. It is also worth mentioning that the system must have an Internet connection during the entire decryption process, otherwise it will fail.

Screenshot of Emsisoft's Djvu decryption service page:

Djvu ransomware decryption service by Emsisoft

Usam ransomware removal:

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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 Usam 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 Usam 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 Usam 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 Usam 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 Usam, 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 Usam 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 Usam 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.

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Usam virus QR code
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