How to remove IISA ransomware (Virus Removal Guide)

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Written by: Stelian Pilici

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If you cannot open your images, documents, or files and they have a .iisa extension, then your computer is infected with the STOP/DJVU ransomware.
This ransomware encrypts the personal documents found on the victim’s computer with the “.iisa” extension, then displays a message which offers to decrypt the data if payment in Bitcoin is made. The instructions are placed on the victim’s desktop in the “_readme.txt” file.

Image: IISA files encrypted
Image: IISA files encrypted
Image: IISA ransomware note
Image: IISA ransomware note

What is the IISA ransomware?

IISA is a file-encrypting ransomware infection that restricts access to data (documents, images, videos) by encrypting files with the “.iisa” extension. It then attempts to extort money from victims by asking for “ransom”, in the form of Bitcoin cryptocurrency, in exchange for access to data.

When you are first infected with the IISA ransomware it will scan your computer for images, videos, and important productivity documents and files such as .doc, .docx, .xls, .pdf. When these files are detected, the ransomware will encrypt them and change their extension to “.iisa”, so that you are no longer able to be open them.

Once the IISA ransomware has encrypted the files on your computer, it will display the “_readme.txt” file that contains the ransom note and instructions on how to contact the authors of this ransomware. The victims of this ransomware will be asked to contact the cybercriminals via the helpmanager@airmail.cc and manager@mailtemp.ch email addresses.

This is the ransom note that the IISA ransomware will show to its victims:

ATTENTION!

Don’t worry, you can return all your files!
All your files like pictures, 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:
https://we.tl/t-fhnNOAYC8Z
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:
manager@mailtemp.ch

Reserve e-mail address to contact us:
helpmanager@airmail.cc

Here is a short summary for the IISA ransomware:

  • Ransomware family: STOP/DJVU ransomware
  • Extensions: .iisa
  • Ransomware note: _readme.txt
  • Ransom: From $490 to $980 (in Bitcoins)
  • Contact: helpmanager@airmail.cc or manager@mailtemp.ch
  • Symptoms: The images, videos, and other documents have the “.iisa” extension and cannot be opened by any programs

How did the IISA ransomware get on my computer?

The IISA ransomware is distributed via spam email containing infected attachments or by exploiting vulnerabilities in the operating system and installed programs.

Here’s how the IISA ransomware might get on your computer:

  • Cyber-criminals spam out an email, with forged header information, tricking you into believing that it is from a shipping company like DHL or FedEx. The email tells you that they tried to deliver a package to you, but failed for some reason. Sometimes the emails claim to be notifications of a shipment you have made. Either way, you can’t resist being curious as to what the email is referring to – and open the attached file (or click on a link inside the email). And with that, your computer is infected with the IISA ransomware.
  • The IISA ransomware was also observed attacking victims by exploiting vulnerabilities in the program installed on the computer or the operating system itself. Commonly exploited software includes the operating system itself, browsers, Microsoft Office, and third-party applications.

Remove the IISA ransomware and recover the files

It’s important to understand that by starting the removal process you risk losing your files, as we cannot guarantee that you will be able to recover them. Your files may be permanently compromised when trying to remove this infection or trying to recover the encrypted documents.

We cannot be held responsible for losing your files or documents during this removal process.
It’s recommended to create a backup image of the encrypted drives or files before proceeding with the malware removal instructions so that you can restore them if the decryption keys are recovered from the cybercriminals’ servers. To create a backup for your encrypted files or drives, you can use EaseUS Todo Backup Free.

This malware removal guide may appear overwhelming due to the number of steps and numerous programs that are being used. We have only written it this way to provide clear, detailed, and easy-to-understand instructions that anyone can use to remove malware for free.
Please perform all the steps in the correct order. If you have any questions or doubts at any point, stop and ask for our assistance.

To remove the IISA ransomware, follow these steps:

STEP 1: Start your computer in Safe Mode with Networking

In this first step, we will start your computer in Safe Mode with Networking to prevent IISA malicious drivers and services from loading at Windows start-up. We’re using Safe mode because it starts Windows in a basic state, using a limited set of files and drivers.

Windows 11Windows 10Windows 7
Before you enter Safe Mode, you need to enter the Windows Recovery Environment (winRE). To do this, follow the below steps:

  1. Press Windows logo key + I on your keyboard to open Settings. If that doesn’t work, right-click on the Start button, then select Settings. In the right window, click on Recovery.
    Go to Windows Settings
  2. Under Advanced startup, select Restart now.
    Recovery window in Windows 10

Now that you are in Windows Recovery Environment, you will follow these steps to take you to safe mode:

  1. On the Choose an option screen, select “Troubleshoot“.
    Windows 11 - Start in Safe Mode with Network
  2. On the “Troubleshoot” screen, click the “Advanced Options” button.
    Windows 11 - Start in Safe Mode with Network - Step 2
  3. On the “Advanced Options” page, click the “Startup Settings” option.
    Windows 11 - Start in Safe Mode with Network - Step 3
  4. On the “Startup Settings” page, click the “Restart”.
    Windows 11 - Start in Safe Mode with Network - Step 4
  5. After your device restarts, you’ll see a list of options. Select option 5 from the list or press F5 to enter Safe Mode with Networking.
    Boot in Safe Mode Windows 11
  6. While your computer is running in Safe Mode with Networking, we will need to download, install and run a scan with Malwarebytes (explained in Step 2).
Before you enter Safe Mode, you need to enter the Windows Recovery Environment (winRE). To do this, follow the below steps:

  1. Press Windows logo key + I on your keyboard to open Settings. If that doesn’t work, select the Start button, then select Settings.
    Go to Windows Settings
  2. When the Windows Settings window opens, select Update & Security, then click on Recovery.
    Recovery window in Windows 10
  3. Under Advanced startup, select Restart now.
    Open Advance Startup

Now that you are in Windows Recovery Environment, you will follow these steps to take you to safe mode:

  1. On the Choose an option screen, select “Troubleshoot“.
    Windows 10 - Start in Safe Mode with Network
  2. On the “Troubleshoot” screen, click the “Advanced Options” button.
    Windows 10 - Start in Safe Mode with Network - Step 2
  3. On the “Advanced Options” page, click the “Startup Settings” option. In Windows 8, this option is labeled “Windows Startup Settings” instead.
    Windows 10 - Start in Safe Mode with Network - Step 3
  4. On the “Startup Settings” page, click the “Restart”.
    Windows 10 - Start in Safe Mode with Network - Step 4
  5. After your device restarts, you’ll see a list of options. Select option 5 from the list or press F5 to enter Safe Mode with Networking.
    Boot in Safe Mode Windows 10
  6. While your computer is running in Safe Mode with Networking, we will need to download, install and run a scan with Malwarebytes (explained in Step 2).
  1. Remove all floppy disks, CDs, and DVDs from your computer, and then restart your computer.
  2. When the computer starts you will see your computer’s hardware being listed. When you see this information start to press the F8 key repeatedly until you are presented with the Advanced Boot Options.
    F8 Safe Mode
  3. In the Advanced Boot Options screen, use the arrow keys to highlight Safe Mode with Networking and then press Enter.
    Safe Mode with Networking screen
  4. While your computer is running in Safe Mode with Networking, we will need to download, install and run a scan with Malwarebytes (explained in Step 2). In some cases, victims may have issues while trying to start the computer in Safe Mode with Networking, if this happens, you can try to scan your computer with Malwarebytes in normal mode.

STEP 2: Use Malwarebytes Free to remove IISA ransomware

While the computer is in Safe Mode with Networking, we will download, install and run a system scan with Malwarebytes.

Malwarebytes Free is one of the most popular and most used anti-malware software for Windows, and for good reasons. It is able to destroy many types of malware that other software tends to miss, without costing you absolutely nothing. When it comes to cleaning up an infected device, Malwarebytes has always been free and we recommend it as an essential tool in the fight against malware.

  1. Download Malwarebytes Free.

    You can download Malwarebytes by clicking the link below.

    MALWAREBYTES DOWNLOAD LINK
    (The above link will open a new page from where you can download Malwarebytes)

  2. Double-click on the Malwarebytes setup file.

    When Malwarebytes has finished downloading, double-click on the MBSetup file to install Malwarebytes on your computer. In most cases, downloaded files are saved to the Downloads folder.

    Double-click on MBSetup installer to install Malwarebytes
    You may be presented with an User Account Control pop-up asking if you want to allow Malwarebytes to make changes to your device. If this happens, you should click “Yes” to continue with the Malwarebytes installation.
    Windows asking for permission to run the Malwarebytes installer

  3. Follow the on-screen prompts to install Malwarebytes.

    When the Malwarebytes installation begins, you will see the Malwarebytes setup wizard which will guide you through the installation process. The Malwarebytes installer will first ask you on what type of computer are you installing this program, click either Personal Computer or Work Computer.
    Malwarebytes setup: Click on Personal Computer step 1

    On the next screen, click “Install” to install Malwarebytes on your computer.
    Malwarebytes Setup: Click on Install

    When your Malwarebytes installation completes, the program opens to the Welcome to Malwarebytes screen. Click the “Get started” button.

  4. Select “Use Malwarebytes Free”.

    After installing Malwarebytes, you’ll be prompted to select between the Free and the Premium version. The Malwarebytes Premium edition includes preventative tools like real-time scanning and ransomware protection, however, we will use the Free version to clean up the computer.
    Click on “Use Malwarebytes Free“.
    Click on Use Malwarebytes Free to continue with the install

  5. Click on “Scan”.

    To scan your computer with Malwarebytes, click on the “Scan” button. Malwarebytes will automatically update the antivirus database and start scanning your computer for malware.
    Click on Scan button to remove IISA ransomware virus

  6. Wait for the Malwarebytes scan to complete.

    Malwarebytes will scan your computer for the IISA malware and other malicious programs. This process can take a few minutes, so we suggest you do something else and periodically check on the status of the scan to see when it is finished.
    Malwarebytes scanning for IISA ransomware virus

  7. Click on “Quarantine”.

    When the scan has completed, you will be presented with a screen showing the malware infections that Malwarebytes has detected. To remove the IISA malicious files that Malwarebytes has found, click on the “Quarantine” button.
    Review the malicious programs and click on Quarantine to remove IISA ransomware virus

  8. Restart computer.

    Malwarebytes will now remove the IISA ransomware malware and other malicious programs that it has found. To complete the malware removal process, Malwarebytes will ask you to restart your computer.
    Malwarebytes requesting to restart computer to complete the IISA ransomware removal process

    When the malware removal process is complete, your computer should start in normal mode (if not, simply restart your device to exit Safe Mode) and continue with the rest of the instructions. We do recommend that you run another scan with Malwarebytes once you’re in Normal mode to make sure all the malicious files were removed.

STEP 3: Scan and clean your computer with HitmanPro

In this third step, while the computer is in normal back, we will download and run a scan with HitmanPro to remove the IISA ransomware and other malicious programs.

HitmanPro is a second opinion scanner that takes a unique cloud-based approach to malware scanning. HitmanPro scans the behavior of active files and also files in locations where malware normally resides for suspicious activity. If it finds a suspicious file that’s not already known, HitmanPro sends it to its clouds to be scanned by two of the best antivirus engines today, which are Bitdefender and Kaspersky.

Although HitmanPro is shareware and costs $24.95 for 1 year on 1 PC, there is actually no limit in scanning. The limitation only kicks in when there is a need to remove or quarantine detected malware by HitmanPro on your system and by then, you can activate the one time 30-days trial to enable the clean up.

  1. Download HitmanPro.

    You can download HitmanPro by clicking the link below.

    HITMANPRO DOWNLOAD LINK
    (The above link will open a new web page from where you can download HitmanPro)

  2. Install HitmanPro.

    When HitmanPro has finished downloading, double-click on “hitmanpro.exe” (for 32-bit versions of Windows) or “hitmanpro_x64.exe” (for 64-bit versions of Windows) to install this program on your PC. In most cases, downloaded files are saved to the Downloads folder.
    Double-click on the HitmanPro setup file - Help Guide
    You may be presented with an User Account Control pop-up asking if you want to allow HitmanPro to make changes to your device. If this happens, you should click “Yes” to continue with the installation.
    Windows asking for permissions to run the HitmanPro setup file - Help Guide

  3. Follow the on-screen prompts.

    When HitmanPro starts you will be presented with the start screen as shown below. Click on the “Next” button to perform a system scan.

    Click Next to install HitmanPro to remove IISA ransomware virus

    HitmanPro final installer screen

  4. Wait for the HitmanPro scan to complete.

    HitmanPro will now begin to scan your computer for the IISA ransomware and other malicious programs. This process will take a few minutes.
    HitmanPro while scanning IISA ransomware

  5. Click on “Next”.

    When HitmanPro has finished the scan, it will display a list of all the malware that the program has found. Click on the “Next” button to remove the IISA ransomware and other malicious programs.
    HitmanPro scan summary. Click Next to delete the IISA ransomware

  6. Click on “Activate free license”.

    Click on the “Activate free license” button to begin the free 30 days trial and remove the IISA ransomware and other malicious files from the computer.
    Activate the free HitmanPro license keyEnter your email to complete the HitmanPro activation - Help Guide

    When the process is complete, you can close HitmanPro and continue with the rest of the instructions.

STEP 4: Double-check for malicious programs with Emsisoft Emergency Kit

In this fourth step, we will scan the computer with Emsisoft Emergency Kit to remove any leftover files from the IISA ransomware and other malicious programs.
While the Malwarebytes and HitmanPro scans are more than enough, we’re recommending Emsisoft Emergency Kit to users who still have malware-related issues or just want to make sure their computer is 100% clean.

Emsisoft Emergency Kit is a free second opinion scanner that can be used without installation to scan and clean infected computers. Emsisoft scans the behavior of active files and also files in locations where malware normally resides for suspicious activity.

  1. Download Emsisoft Emergency Kit.

    You can download Emsisoft Emergency Kit by clicking the link below.

    EMSISOFT EMERGENCY KIT DOWNLOAD LINK
    (The above link will open a new web page from where you can download Emsisoft Emergency Kit)

  2. Install Emsisoft Emergency Kit.

    Double-click on the EmsisoftEmergencyKit setup file to start the installation process, then click on the “Install” button.
    Click on the Install button

  3. Start Emsisoft Emergency Kit.

    On your desktop the “EEK” folder (C:\EEK) should now be open. To start Emsisoft, click on the “Start Emsisoft Emergency Kit” file to open this program.
    Click on Start Emsisoft Emergency Kit to remove the IISA ransomware

    You may be presented with a User Account Control dialog asking you if you want to run this file. If this happens, you should click “Yes” to continue with the installation.
    Allow Emsisoft to run on your PC - UAC

  4. Click on “Malware Scan”.

    Emsisoft Emergency Kit will start and it will ask you for permission to update itself. Once the update process is complete, click on the “Scan” tab, and perform a “Malware Scan“.

    Perform a Malware Scan with Emsisoft Emergency Kit
    Emsisoft Emergency Kit will now scan your computer for the IISA malicious files. This process can take a few minutes.
    Emsisoft Emergency Kit Scanning for the IISA ransomware

  5. Click on “Quarantine selected”.

    When the Emsisoft scan has finished, you will be presented with a screen reporting which malicious files were detected on your computer. To remove the IISA ransomware, click on the “Quarantine selected“.
    Click on Quarantine Selected to remove the IISA virus
    When the malware removal process is complete, Emsisoft Emergency Kit may need to restart your computer. Click on the “Restart” button to restart your computer.
    When the process is complete, you can close Emsisoft and continue with the rest of the instructions.

STEP 5: Restore the files encrypted by the IISA ransomware

Unfortunately, in most cases, it’s not possible to recover the files encrypted by the IISA ransomware because the private key which is needed to unlock the encrypted files is only available through the cybercriminals. However, below we’ve listed two options you can use to try and recover your files.

Make sure you remove the malware from your computer first, otherwise, it will repeatedly lock your system or encrypt files. If you suspect that your computer is still infected with malware, you can run a free scan with ESET Online Scanner.

Option 1: Use Emsisoft Decryptor for STOP Djvu to restore the files

If your files were encrypted with an offline key there is a chance you can recover them by using Emsisoft Decryptor for STOP Djvu decryption tool. Follow the below guide to recover your files using the Emsisoft Decryptor for STOP Djvu.

  1. Download Emsisoft Decryptor for STOP Djvu

    You can download Emsisoft Decryptor for STOP Djvu by clicking the link below.

    EMSISOFT DECRYPTOR FOR STOP DJVU DOWNLOAD LINK
    (The above link will open a new web page from where you can download Emsisoft Decryptor for STOP Djvu)

  2. Run Emsisoft Decryptor for STOP Djvu

    When Emsisoft Decryptor for STOP Djvu has finished downloading, double-click on “decrypt_STOPDjvu.exe” to run this program on your computer. In most cases, downloaded files are saved to the Downloads folder.

    Double-click on the Emsisoft Decryptor for STOP Djvu icon to decrypt the IISA files

    You may be presented with a User Account Control pop-up asking if you want to allow Emsisoft to make changes to your device. If this happens, you should click “Yes” to continue with the installation.

  3. Follow the on-screen prompts

    When the Emsisoft Decryptor for STOP Djvu starts, you will need to agree with the Terms and accept a disclaimer.
    Click Yes to Continue to decrypt IISA ransomware

  4. Click on “Decrypt”.

    Click the “Decrypt” button to start the decryption process. The screen will switch to a status view, informing you about the current process and decryption status of your files.

    Click Decrypt to recover from IISA ransomware

  5. The decryptor will inform you once the decryption process is finished. If you require the report for your personal records, you can save it by clicking the “Save log” button. If your system was compromised through the Windows Remote Desktop feature, we also recommend changing all passwords of all users that are allowed to login remotely and checking the local user accounts for additional accounts the attacker might have added.

If the “Emsisoft Decryptor for STOP Djvu” can’t decrypt your documents and you do not plan on paying the ransom, it is advised that you make an image of the encrypted drives so that you can possibly decrypt them in the future.

Option 2: Search for a IISA ransomware decryption tool

The cybersecurity community is constantly working to create ransomware decryption tools, so you can try to search these sites for updates:

Your computer should now be free of the IISA ransomware infection. If your current antivirus allowed this malicious program on your computer, you may want to consider purchasing the full-featured version of Malwarebytes Anti-Malware to protect against these types of threats in the future.
If you are still having problems with your computer after completing these instructions, then please follow one of the steps:

How to Stay Safe Online

Here are 10 basic security tips to help you avoid malware and protect your device:

  1. Use a good antivirus and keep it up-to-date.

    Shield Guide

    It's essential to use a good quality antivirus and keep it up-to-date to stay ahead of the latest cyber threats. We are huge fans of Malwarebytes Premium and use it on all of our devices, including Windows and Mac computers as well as our mobile devices. Malwarebytes sits beside your traditional antivirus, filling in any gaps in its defenses, and providing extra protection against sneakier security threats.

  2. Keep software and operating systems up-to-date.

    updates-guide

    Keep your operating system and apps up to date. Whenever an update is released for your device, download and install it right away. These updates often include security fixes, vulnerability patches, and other necessary maintenance.

  3. Be careful when installing programs and apps.

    install guide

    Pay close attention to installation screens and license agreements when installing software. Custom or advanced installation options will often disclose any third-party software that is also being installed. Take great care in every stage of the process and make sure you know what it is you're agreeing to before you click "Next."

  4. Install an ad blocker.

    Ad Blocker

    Use a browser-based content blocker, like AdGuard. Content blockers help stop malicious ads, Trojans, phishing, and other undesirable content that an antivirus product alone may not stop.

  5. Be careful what you download.

    Trojan Horse

    A top goal of cybercriminals is to trick you into downloading malware—programs or apps that carry malware or try to steal information. This malware can be disguised as an app: anything from a popular game to something that checks traffic or the weather.

  6. Be alert for people trying to trick you.

    warning sign

    Whether it's your email, phone, messenger, or other applications, always be alert and on guard for someone trying to trick you into clicking on links or replying to messages. Remember that it's easy to spoof phone numbers, so a familiar name or number doesn't make messages more trustworthy.

  7. Back up your data.

    backup sign

    Back up your data frequently and check that your backup data can be restored. You can do this manually on an external HDD/USB stick, or automatically using backup software. This is also the best way to counter ransomware. Never connect the backup drive to a computer if you suspect that the computer is infected with malware.

  8. Choose strong passwords.

    lock sign

    Use strong and unique passwords for each of your accounts. Avoid using personal information or easily guessable words in your passwords. Enable two-factor authentication (2FA) on your accounts whenever possible.

  9. Be careful where you click.

    cursor sign

    Be cautious when clicking on links or downloading attachments from unknown sources. These could potentially contain malware or phishing scams.

  10. Don't use pirated software.

    Shady Guide

    Avoid using Peer-to-Peer (P2P) file-sharing programs, keygens, cracks, and other pirated software that can often compromise your data, privacy, or both.

To avoid potential dangers on the internet, it's important to follow these 10 basic safety rules. By doing so, you can protect yourself from many of the unpleasant surprises that can arise when using the web.

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