ISZA ransomware locks files by encrypting them
Contents
ISZA ransomware is a hazardous computer virus that spreads in disguise of various software cracks. Once downloaded and launched on a system, it begins encrypting all files and appending .isza extensions to filenames. Once encrypted, data can no longer be opened, no matter what program the user chooses to use for the task. In addition, this ransomware creates ransom notes called _readme.txt and saves them in several affected data folders. This malware is a recognized variant of STOP/DJVU ransomware family, which is known to demand $490-$980 as a ransom in exchange for data decryption tool.
To illustrate how files are renamed during the computer attack, see the following example: files previously named as 1.jpg, 2.mp3, 3.xls will appear as 1.jpg.isza, 2.mp3.isza, 3.xls.isza and the rest of the data names will look similarly.

Ransom note contents: the criminals demand payment for the decryption tool
The ransom note dropped by this malware explains that the only way to decrypt .isza files is by obtaining the tool from the cybercriminals. According to the message left in _readme.txt file, the criminals expect the victim to contact the within given email addresses (support@fishmail.top, datarestorehelp@airmail.cc) within 3 days, and doing so guarantees a 50% discount on the ransom amount, meaning ISZA file decryption tools would cost $490 instead of $980.
The note also recommends testing the decryption procedure before paying the ransom. In order to do this, victim can send one encrypted file to the criminals via email and wait for their reply with a recovered file version attached.
However, even if they do send a healthy file back, paying a ransom is NOT a recommended option. We suggest reading these recommendations for ransomware victims by FBI and also these response recommendations from NCSC.

What’s not covered in the ransom note is additional malware that was dropped during the ransomware attack. It appears that the malicious file used to drop ISZA ransomware on the system also launches Vidar, Azorult or RedLine Stealers. These all fall into category of Remote Access Trojans (RATs) that can be used to steal and transfer collected sensitive information from the victim’s computer to the criminals’ server.
Therefore, the best decision for those affected by the described malware is to remove ISZA ransomware virus as well as any additional threats that came alongside it. To delete the malicious components from the system, follow the instructions provided in this article. You can use any antivirus you like, but if you do not have one yet installed on your computer, then we strongly recommend using . Afterward, consider downloading RESTORO (secure download link) to perform a system scan, identify and repair affected Windows OS files.
Ransomware Summary
Name | ISZA Ransomware Virus |
Type | Ransomware; Crypto-malware; Virtual Extortion Virus |
Family | STOP/DJVU |
Encryption type | RSA 2048 + Salsa20 |
Previous versions | JYPO, KIFR, KIOP, KITZ, BOZA, BOTY, COZA (find full list here) |
Version | 622nd |
Extension | .isza |
Cybercriminal emails | support@fishmail.top and datarestorehelp@airmail.cc |
Additional malware dropped | Azorult or Vidar Trojan |
Damage | The ransomware uses encryption to maliciously modify all files on the PC and marks their original names with .isza extension. Ransom notes called as _readme.txt will be dropped in every computer folder. This piece of malware usually drags VIDAR Stealer alongside it and also eliminates VSS from the system. On top of that, it tends to modify Windows HOSTS file to restrict computer user’s access to cybersecurity-related websites online. |
Ransom note | _readme.txt |
Ransom demand | $490-$980 in Bitcoin |
Distribution | Victims often download this ransomware along illegal torrent downloads, cracked software, activators, key generators or tools like KMSPico. |
Known software cracks to contain this malware | Corel Draw, Tenorshare 4ukey, Adobe Photoshop, Cubase, Adobe Illustrator, Internet Download Manager, Tally, League of Legends. |
Detection names | Trojan:Win32/Azorult.FW!MTB (Microsoft), Gen:Heur.Mint.Zard.52 (B) (Emsisoft), HEUR:Trojan.Win32.Scarsi.gen (Kaspersky), Gen:Heur.Mint.Zard.52 (BitDefender), Trojan.MalPack.GS (Malwarebytes), ML.Attribute.HighConfidence (Symantec) see all detection name variations on VirusTotal |
Removal | Remove ransomware and related malware from your PC using trustworthy software like INTEGO Antivirus. To repair virus damage on Windows OS files, download and try RESTORO (secure download link). |

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Ransomware distribution techniques to know
Computer users should get familiar with the most common ransomware distribution techniques. In general, these distribution tactics are used to spread all kinds of malware, so it is beneficial for the computer user to know them in order to avoid getting infected.
STOP/DJVU ransomware variants such as ISZA virus can usually be found in illegal online software sharing resources, such as crack or warez websites. These websites usually provide either direct download links or torrent files so that the user could download fake installation files. Victims usually download them in belief that these will help to smoothly install paid software versions for free.
The only way to get legitimate and secure computer software versions is to download them from trustworthy websites. Ideally, you should visit its official website or those of partner websites, if you’re looking for some deals. Users who attempt to cut corners and install cracked or pirated versions usually end up infecting their computers with severe malware, such as ransomware, Trojans, miners, and other threat types.
Cybercriminals also actively use email spam to distribute ransomware. They usually inject a malicious malware-downloading script into regular file types that support scripts, for example, Word, PDF, or XLS files, and name them as invoices or order summaries.
Unfortunately, if the user downloads and opens such file, the malicious code triggers and compromises the entire computer system and files in it. For this reason, users should avoid opening email attachments that come from unrecognized senders. Additionally, one should always check whether the email was actually sent by the person or company that the email claims to be.
Remove ISZA Ransomware Virus and Decrypt Your Files
Computer users affected by this notorious malware should rush to remove ISZA ransomware virus – the sooner, the better. The guide provided below explains the recommended procedure in detail. You can use antivirus software that you like and trust, but if you do not have one yet, consider trying the one we recommend – INTEGO Antivirus. You can read Intego AV review on our website.
Afterward, we recommend that you download RESTORO to scan the computer system and check if there is any damage to Windows OS files that can be repaired. In addition, we advise you to change all of the passwords used on the compromised machine due to potential data theft inflicted by Trojans that accompany the ransomware.
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Our team recommends a two-step rescue plan to remove ransomware and other remaining malware from your computer, plus repair caused virus damage to the system:
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ISZA Ransomware Virus Removal Guidelines
Method 1. Enter Safe Mode with Networking
Step 1. Start Windows in Safe Mode with Networking
Before you try to remove ISZA Ransomware Virus virus, you must start your computer in Safe Mode with Networking. Below, we provide the easiest ways to boot PC in the said mode, but you can find additional ones in this in-depth tutorial on our website – How to Start Windows in Safe Mode. Also, if you prefer a video version of the tutorial, check our guide How to Start Windows in Safe Mode on Youtube.
Instructions for Windows XP/Vista/7 users
- First of all, turn off your PC. Then press the Power button to start it again and instantly start pressing F8 button on your keyboard repeatedly in 1-second intervals. This launches the Advanced Boot Options menu.
- Use arrow keys on the keyboard to navigate down to Safe Mode with Networking option and press Enter.
Instructions for Windows 8/8.1/10/11 users
- Open Windows Start menu, then press down the Power button. On your keyboard, press down and hold the Shift key, and then select Restart option.
- This will take you to Windows Troubleshoot screen. Choose Troubleshoot > Advanced Options > Startup Settings > Restart. Tip: If you can't find Startup Settings, click See more recovery options.
- In Startup Settings, press the right key between F1-F9 to enter Safe Mode with Networking. In this case, it is the F5 key.
Step 2. Remove files associated with the virus
Now, you can search for and remove ISZA Ransomware Virus files. It is very hard to identify files and registry keys that belong to the ransomware virus, Besides, malware creators tend to rename and change them repeatedly. Therefore, the easiest way to uninstall such type of a computer virus is to use a reliable security program such as INTEGO Antivirus. For virus damage repair, consider using RESTORO.
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Method 2. Use System Restore
In order to use System Restore, you must have a system restore point, created either manually or automatically.
Step 1. Boot Windows in Safe Mode with Command Prompt
Instructions for Windows XP/Vista/7 users
- Shut down your PC. Start it again by pressing the Power button and instantly start pressing F8 button on your keyboard repeatedly in 1-second intervals. You will see Advanced Boot Options menu.
- Using arrow keys on the keyboard, navigate down to Safe Mode with Command Prompt option and press Enter.
Instructions for Windows 8/8.1/10/11 users
- Launch Windows Start menu, then click the Power button. On your keyboard, press down and hold the Shift key, and then choose Restart option with the mouse cursor.
- This will take you to Windows Troubleshoot screen. Choose Troubleshoot > Advanced Options > Startup Settings > Restart. Tip: If you can't find Startup Settings, click See more recovery options.
- In Startup Settings, press the right key between F1-F9 to enter Safe Mode with Command Prompt. In this case, press F6 key.
Step 2. Start System Restore process
- Wait until system loads and command prompt shows up.
- Type cd restore and press Enter, then type rstrui.exe and press Enter. Or you can just type %systemroot%system32restorerstrui.exe in command prompt and hit Enter.
- This launches System Restore window. Click Next and then choose a System Restore point created in the past. Choose one that was created before ransomware infection.
- Click Yes to begin the system restoration process.
After restoring the system, we recommend scanning the system with antivirus or anti-malware software. In most cases, there won't be any malware remains, but it never hurts to double-check. In addition, we highly recommend checking ransomware prevention guidelines provided by our experts in order to protect your PC against similar viruses in the future.
Alternative software recommendations
Malwarebytes Anti-Malware
Removing spyware and malware is one step towards cybersecurity. To protect yourself against ever-evolving threats, we strongly recommend purchasing a Premium version of Malwarebytes Anti-Malware, which provides security based on artificial intelligence and machine learning. Includes ransomware protection. See pricing options and protect yourself now.
System Mechanic Ultimate Defense
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Disclaimer. This site includes affiliate links. We may earn a small commission by recommending certain products, at no additional cost for you. We only choose quality software and services to recommend.
Decrypt ISZA files
Fix and open large ISZA files easily:
It is reported that STOP/DJVU ransomware versions encrypt only the beginning 150 KB of each file to ensure that the virus manages to affect all files on the system. In some cases, the malicious program might skip some files at all. That said, we recommend testing this method on several big (>1GB) files first.
- Create a copy of encrypted file to a separate folder using Copy > Paste commands.
- Now, right-click the created copy and choose Rename. Select the ISZA extension and delete it. Press Enter to save changes.
- In the prompt asking whether you want to make the changes as file might become unusable, click OK.
- Try opening the file.
STOP/DJVU decryption tool usage guide
STOP/DJVU ransomware versions are grouped into old and new variants. ISZA Ransomware Virus is considered the new STOP/DJVU variant, just like JYPO, KIFR, KIOP, KITZ, BOZA, BOTY, COZA (find full list here). This means full data decryption is now possible only if you have been affected by offline encryption key. To decrypt your files, you will have to download Emsisoft Decryptor for STOP DJVU, a tool created and maintained by a genius security researcher Michael Gillespie.
Note! Please do not spam the security researcher with questions whether he can recover your files encrypted with online key - it is not possible.
In order to test the tool and see if it can decrypt ISZA files, follow the given tutorial.
- Download the decryption tool from Emsisoft.
- Click the little arrow next to your download and choose Show in Folder.
- Now, right-click the file and choose Run as Administrator. If asked, enter administrator's password.
- In UAC window, click Yes.
- Click Yes to agree to software terms in both windows.
- The tool will automatically include C:// disk as a location to decrypt. The file recovery tool will prepopulate the locations to scan, including connected data storage drives or network drives. Click Add folder if you wish to add additional locations.
In Options tab, you can choose to keep encrypted file copies. We recommend leaving this option selected, especially if you do not know if the decryption tool will work. - Click Decrypt to start restoring ISZA files. You will see the progress in the Results tab. Here, you can see messages from the tool, such as whether the decryption procedure is successful, or you need to wait for an update.
You might also be informed that online key was used to encrypt your files. In such case, the decryption tool won't work for you, and the only way to recover your files is to use a data backup.
Meanings of decryptor's messages
The ISZA decryption tool might display several different messages after failed attempt to restore your files. You might receive one of the following messages:
Error: Unable to decrypt file with ID: [example ID]
This message typically means that there is no corresponding decryption key in the decryptor's database.
No key for New Variant online ID: [example ID]
Notice: this ID appears to be an online ID, decryption is impossible
This message informs that your files were encrypted with online key, meaning no one else has the same encryption/decryption key pair, therefore data recovery without paying the criminals is impossible.
Result: No key for new variant offline ID: [example ID]
This ID appears to be an offline ID. Decryption may be possible in the future.
If you were informed that an offline key was used, but files could not be restored, it means that the offline decryption key isn't available yet. However, receiving this message is extremely good news, meaning that it might be possible to restore your ISZA extension files in the future. It can take a few months until the decryption key gets found and uploaded to the decryptor. We recommend you to follow updates regarding the decryptable DJVU versions here. We strongly recommend backing up your encrypted data and waiting.
Report Internet crime to legal departments
Victims of ISZA Ransomware Virus should report the Internet crime incident to the official government fraud and scam website according to their country:
- In the United States, go to the On Guard Online website.
- In Australia, go to the SCAMwatch website.
- In Germany, go to the Bundesamt für Sicherheit in der Informationstechnik website.
- In Ireland, go to the An Garda Síochána website.
- In New Zealand, go to the Consumer Affairs Scams website.
- In the United Kingdom, go to the Action Fraud website.
- In Canada, go to the Canadian Anti-Fraud Centre.
- In India, go to Indian National Cybercrime Reporting Portal.
- In France, go to the Agence nationale de la sécurité des systèmes d’information.
If you can't find an authority corresponding to your location on this list, we recommend using any search engine to look up "[your country name] report cyber crime". This should lead you to the right authority website. We also recommend staying away from third-party crime report services that are often paid. It costs nothing to report Internet crime to official authorities.
Another recommendation is to contact your country's or region’s federal police or communications authority.
Frequently Asked Questions
You can only open ISZA files if you have the decryption key, or if you were affected by offline encryption type.
To figure out whether you were affected by offline encryption, please go to C:/SystemID/PersonalID.txt and see if the string inside of it ends in t1. You can also try using Emsisoft Decryptor for STOP/DJVU.
Please follow the guidances provided by the official ISZA decryption tools and believe what they say. If they say it is impossible to decrypt, it really is so. There is no magic tool or human capable of decrypting your files hiding somewhere. Encryption is a technique created to be nearly impossible to decrypt without a special private key (held by the criminals).
We advise scanning with anti-virus, anti-malware, malware removal tools or software like RESTORO to eliminate virus damage on the system. If you do not trust using a single tool, try running one after another. However, we do not recommend keeping several security programs on a computer at once as they can interfere with each other's work.
Beware of fake ISZA decryption tools circulating around the web. Cyber criminals are uploading them to various shady websites, also might be promoting them via suspicious Youtube videos. These programs can infect your computer even more heavily (Trojans, miners, etc.). We suggest being extremely cautious around the web. If there will be an official STOP/DJVU decryption tool available, it will be widely discussed in public media.

Norbert Webb is the head of Geek’s Advice team. He is the chief editor of the website who controls the quality of content published. The man also loves reading cybersecurity news, testing new software and sharing his insights on them. Norbert says that following his passion for information technology was one of the best decisions he has ever made. “I don’t feel like working while I’m doing something I love.” However, the geek has other interests, such as snowboarding and traveling.
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