Remove ASSM Ransomware Virus (DECRYPT .assm FILES)

remove ASSM ransomware virus and learn how to decrypt or repair files with .assm extension (free guide)

What you need to know when ASSM ransomware hits you

Contents

What you need to know when ASSM ransomware hits you
- What’s explained in the ransom note?
- Ransomware Summary
Get to know ransomware distribution techniques
Remove ASSM ransomware virus and protect your computer
Decrypt ASSM files
Frequently Asked Questions

ASSM ransomware is a malicious computer virus that is recognized as a variant from the STOP/DJVU ransomware family. The purpose of this malicious program is to encrypt all files on infected computers, making them inaccessible to their original owner. During the attack, the malware marks each affected file by appending an additional .assm extension. In addition, the malware leaves copies of a ransom note (_readme.txt) file in various computer folders.

To understand how files are renamed, see the following example: files originally named 1.jpg, 2.docx and 3.mp4 will appear as 1.jpg.assm, 2.docx.assm, and 3.mp4.assm once modified by the ransomware. Afterward, no program will be capable of opening them, and so the criminals will require purchasing a decryption software and private key from them for a ransom.

What’s explained in the ransom note?

The ransom note provided by the ransomware operators is stored in _readme.txt files dropped across various computer folders. It asks for victim’s attention and explains that all data has been encrypted with the strongest algorithm and private key. It also suggests that the only way to decrypt .assm files is to purchase a decryption tool from the cybercriminals. In other words, it asks the victim to pay a ransom.

The note further explains that the victim should contact the attackers via provided email addresses – support@freshmail.top and datarestorehelp@airmail.cc. It also recommends attaching one encrypted file and victim’s Personal ID that’s included in the ransom note. The note explains that the criminals can decrypt the test file in order to prove that they can restore the rest of the data.

They also provide the pricing of the decryption tool, which depends on how quickly the victim acts upon getting hit by the ransomware. According to the note, all victims who contact the attackers within 72 hours after being infected can get a 50% discount and pay $490 instead of $980 for decryption tool. Otherwise, the victim will have to pay the full amount.

Cybersecurity experts do not recommend paying the ransom. The same idea is supported by the official FBI guidelines for ransomware victims. Paying the ransom never guarantees full data recovery, besides, it encourages the attackers to continue their filthy business. Moreover, by paying up, you would make yourself a desirable target in future attacks.

Another important thing that victims of ASSM ransomware should know is that this specific malware often arrives together with information-stealing Trojans. Vidar, Azorult and RedLine are just a couple of stealer malware samples spotted alongside this ransomware. These Trojans can transmit information stolen from a computer to attackers and allow them to hack your accounts, contents of offline cryptocurrency wallets, or drop additional malware on the computer.

If you have found your files encrypted by the described virus, we strongly recommend taking action to secure your computer ASAP. The best way to do this is by using a powerful antivirus software, for example, INTEGO Antivirus. Another useful tool that our team recommends can be downloaded here – RESTORO. It is a tool that can repair damaged Windows OS files.

Ransomware Summary

Name	ASSM Ransomware Virus
Type	Ransomware; Crypto-malware; Virtual Extortion Virus
Family	STOP/DJVU
Encryption type	RSA 2048 + Salsa20
Previous versions	KAAA, BGJS, BGZQ (find full list here)
Version	638th
Extension	.assm
Cybercriminal emails	support@freshmail.top, datarestorehelp@airmail.cc
Additional malware dropped	Azorult, RedLine or Vidar
Damage	The ransomware uses encryption to maliciously modify all files on the PC and marks their original names with .mztu 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, HP/Epson printer drivers, 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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Get to know ransomware distribution techniques

In order to avoid getting struck by such dangerous ransomware like ASSM virus or any other similar threat, you should know general ransomware distribution tactics. Most of the time, these threats are distributed in a form of malicious email attachments, disguised as software cracks or provided along untrustworthy freeware or software update installers.

The most prevalent distribution method closely associated with the STOP/DJVU ransomware variants is pirated/cracked software versions made available to download in various rogue websites. Computer users who seek to install premium software versions for free may stumble upon these fake downloads and invite them into their computers without realising the risk. You may also want to read these reasons why you shouldn’t download cracked software.

Another common ransomware distribution method is malicious email spam. Cybercriminals send out mass emails using email lists they buy off dark web markets and include malware-laced attachments. Typically, these files are named as invoices, order summaries, waybills or other documents. If the victim opens this file, the malware instantly launches on the system.

Finally, malware can be distributed via untrustworthy websites that push aggressive ads from untrustworthy ad networks. Some of these deceptive ads claim the user needs to install “recommended” software in order to fix computer issues. Sometimes, users infect their computers with downloads from pages that require downloading “recommended” software before the requested file is provided.

In order to avoid getting infected with ransomware or other type of malware, it is strongly recommended that computer users stay vigilant while browsing the Internet and avoid installing unwanted software. In general, you should not download any files from websites that seem untrustworthy or suspicious. In addition, users should also remain cautious when checking their emails and never open links or attachments sent by unsolicited senders.

Finally, protecting your computer with a robust AV software is simply a must, because it can guard your computer and inform you about dangerous files or online websites even if you fail to identify the risk.

Remove ASSM ransomware virus and protect your computer

It is important to remove ASSM ransomware virus from a compromised computer because allowing it to stay causes high security risks. For example, it can spread to any device you connect to your computer and encrypt data stored on it.

To implement ASSM ransomware removal, use the instructions provided below. After deleting all malware from your computer, do not forget to change all your passwords used on the compromised computer (due to information-stealing Trojan activity).

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ASSM 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 ASSM 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 ASSM 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.

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Decrypt ASSM files

Fix and open large ASSM 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 ASSM 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. ASSM Ransomware Virus is considered the new STOP/DJVU variant, just like KAAA, BGJS, BGZQ (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 ASSM 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 ASSM 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 ASSM 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 ASSM 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 ASSM 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

✓ How can I open .ASSM files?

You can only open ASSM files if you have the decryption key, or if you were affected by offline encryption type.

✓ How do I know if my files were encrypted with offline or online encryption?

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.

✓ My files contain very important information (family memories). Every tool I used says it is impossible to decrypt. What should I do?

Please follow the guidances provided by the official ASSM 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).

✓ I am afraid virus is still in my computer system. What should I do?

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.

✓ I saw several Youtube videos suggesting secret decryption tools. Can I trust them?

Beware of fake ASSM 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

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.