Back (.back) ransomware virus - removal and decryption options
Written by Tomas Meskauskas on (updated)
What kind of malware is Back?
Belonging to the Dharma/Crysis family ransomware family, Back is malicious software designed to encrypt data and demand ransom payments for decryption. When Back encrypts, all affected files are appended with the victim's unique ID, the developer's email address and the ".back" extension.
For example, a file originally named "1.jpg" would appear as something similar to "1.jpg.id-1E857D00.[metron28@protonmail.com].back", and so on. Updated variants of Back ransomware append ".[Backdata@zimbabwe.su].Back" and "[backdata@qbmail.biz].back" extensions.
Once this process is finished, a text file ("FILES ENCRYPTED.txt") is stored on the desktop and a pop-up window is displayed.
Screenshot of files encrypted by Back (".back" extension):
Ransom note overview
The text file ("FILES ENCRYPTED.txt") informs victims that their data has been "locked" and, if they wish to "unlock" it, they must contact the cyber criminals behind Back via the email addresses provided. The text presented in the pop-up window is a more detailed ransom message, which clarifies that the compromised files have been encrypted.
The email users are required to send must contain their ID in the subject/title field (the ID is generated individually for each victim and can be found in the pop-up, and within the filenames of encrypted files). If there is no answer from the ransomware developers within 24 hours, victims can use the alternative email address to establish contact.
How quickly users initiate communication will determine the size of the ransom they must pay. The sum must be paid in the Bitcoin cryptocurrency (the message also lists links detailing how to and from where to acquire Bitcoins). Prior to paying, victims are permitted to send one encrypted file from their device to test decryption.
The test file size cannot exceed 1 MB (non-archived) and must not contain valuable information (e.g. backups, databases, large excel sheets, etc.). Following payment, the criminals promise that users will receive all necessary tools to restore their data.
The message warns that renaming the encrypted files and/or trying to decrypt them with third party software can result in permanent data loss (i.e., render files beyond repair).
More about Back ransomware
Back is a sophisticated malware that undermines system security by deactivating the firewall, erasing Volume Shadow Copies, and exploiting vulnerabilities in Remote Desktop Protocol services.
It gains unauthorized access through brute force and dictionary attacks on systems with weak credentials. The malware's persistence is concerning as it encrypts and compromises the system and collects location data.
Back employs a multifaceted strategy, demonstrating strategic and sophisticated tactics to compromise and maintain control over the compromised system.
Ransomware in general
Ransomware encryption cannot generally be broken (decrypted) without the involvement of the individuals responsible for the attack, unless (in rare case) the malicious program is still in development and/or has certain flaws/bugs. Regardless, you are strongly advised against meeting the demands of cyber criminals.
People who pay often receive none of the necessary tools/software to decrypt their data. Therefore, their files remain encrypted and useless, and they also experience financial loss.
To prevent Back from further encryption, it must be eliminated from the operating system, however, removal will not restore already affected data. The only viable solution is to recover files from a backup, if one was made before the infection and was stored in a separate location.
Tl30z, Helpforyoupc, Dever and Horriblemorning are examples of other ransomware-type programs. All malware within this category encrypts data and demands payment for decryption tools/software. Key differences are the cryptographic algorithm they use (symmetric or asymmetric) and ransom size.
The latter can vary between three-digit and four-digit sums (in USD).
The demanded currencies are typically digital (mainly cryptocurrencies), since these transactions are difficult/impossible to trace. To protect files from data encryption and damaging attacks, you are advised to keep backups on unplugged storage devices and/or remote servers. Ideally, backup copies should be stored in several different locations.
How did ransomware infect my computer?
The main modes of ransomware and other malware proliferation are via spam campaigns, trojans, untrustworthy download channels, fake software updaters and illegal activation tools ("cracks"). Spam campaigns are used to send thousands of deceptive emails containing infectious files (or links leading to them).
The dangerous files come in various formats (e.g. PDF and Microsoft Office documents, archive and executable files, JavaScript, etc.). When opened, the infection process begins. Therefore, executing, running or otherwise opening infectious files triggers them to start downloading/installing malicious programs.
Trojans are malware programs capable of causing chain infections. Peer-to-Peer sharing networks (BitTorrent, eMule, Gnutella, etc.), free file-hosting and unofficial websites, third party downloaders and similar download sources are untrustworthy. These download channels are more likely to offer malicious content disguised as normal software and/or bundled (packed) with it.
Fake updaters exploit weaknesses present in outdated programs and/or install malware rather than the promised updates. Illegal activation ("cracking") tools infect systems similarly by downloading/installing malicious software rather than activating licensed products.
| Name | Back virus |
| Threat Type | Ransomware, Crypto Virus, Files locker. |
| Encrypted Files Extension | .back (files are also appended with a unique ID and the developer's email address). |
| Ransom Demand Message | FILES ENCRYPTED.txt and pop-up window. |
| Cyber Criminal Contact | metron28@protonmail.com, metron28@cock.li, backk_filess@protonmail.ch, back_files_now@tuta.io, recowerdata@protonmail.com, backdata@qbmail.biz |
| Detection Names | Avast (Win32:RansomX-gen [Ransom]), BitDefender (Trojan.Ransom.Crysis.E), ESET-NOD32 (A Variant Of Win32/Filecoder.Crysis.P), Kaspersky (Trojan-Ransom.Win32.Crusis.to), Full List Of Detections (VirusTotal) |
| Rogue Process Name | Came Intranet Beads Arll Filename |
| 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. |
| Distribution methods | Infected email attachments (macros), torrent websites, malicious ads. |
| 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 Combo Cleaner. |
How to protect yourself from ransomware infections
Do not open suspicious and/or irrelevant emails. All attachments (and/or links) found in dubious mail must never be opened, as these files are the origin of a potential infection. Use official and verified download sources. Furthermore, software must be activated and updated with tools/functions provided by legitimate developers.
Illegal activation tools ("cracks") and third party updaters are high-risk, as they are frequently used to proliferate malware. It is paramount to device health to have a reputable anti-virus/anti-spyware suite installed and kept updated. These programs should be used for regular system scans and removal of detected threats/issues.
If your computer is already infected with Back, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.
Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:
Text presented in Back ransomware pop-up window:
All your files have been encrypted!
All your files have been encrypted due to a security problem with your PC. If you want to restore them, write us to the e-mail metron28@protonmail.com
Write this ID in the title of your message 1E857D00
In case of no answer in 24 hours write us to theese e-mails:metron28@cock.li
You have to pay for decryption in Bitcoins. The price depends on how fast you write to us. After payment we will send you the decryption tool that will decrypt all your files.
Free decryption as guarantee
Before paying you can send us up to 1 file for free decryption. The total size of files must be less than 1Mb (non archived), and files should not contain valuable information. (databases,backups, large excel sheets, etc.)
How to obtain Bitcoins
The easiest way to buy bitcoins is LocalBitcoins site. You have to register, click 'Buy bitcoins', and select the seller by payment method and price.
hxxps://localbitcoins.com/buy_bitcoins
Also you can find other places to buy Bitcoins and beginners guide here:
hxxp://www.coindesk.com/information/how-can-i-buy-bitcoins/
Attention!
Do not rename encrypted files.
Do not try to decrypt your data using third party software, it may cause permanent data loss.
Decryption of your files with the help of third parties may cause increased price (they add their fee to our) or you can become a victim of a scam.
Screenshot of Back text file ("FILES ENCRYPTED.txt"):
Text presented in this file:
all your data has been locked us
You want to return?
write email metron28@protonmail.com or metron28@cock.li
Screenshot of Back ransomware process on Windows Task Manager ("Came Intranet Beads Arll Filename"):
Back ransomware removal:
Instant automatic malware removal:
Manual threat removal might be a lengthy and complicated process that requires advanced IT skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
▼ DOWNLOAD Combo Cleaner
By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. To use full-featured product, you have to purchase a license for Combo Cleaner. 7 days free trial available. Combo Cleaner is owned and operated by Rcs Lt, the parent company of PCRisk.com read more.
Video suggesting what steps should be taken in case of a ransomware infection:
Quick menu:
- What is Back virus?
- STEP 1. Reporting ransomware to authorities.
- STEP 2. Isolating the infected device.
- STEP 3. Identifying the ransomware infection.
- STEP 4. Searching for ransomware decryption tools.
- STEP 5. Restoring files with data recovery tools.
- STEP 6. Creating data backups.
If you are a victim of a ransomware attack we recommend reporting this incident to authorities. By providing information to law enforcement agencies you will help track cybercrime and potentially assist in the prosecution of the attackers. Here's a list of authorities where you should report a ransomware attack. For the complete list of local cybersecurity centers and information on why you should report ransomware attacks, read this article.
List of local authorities where ransomware attacks should be reported (choose one depending on your residence address):
USA - Internet Crime Complaint Centre IC3
United Kingdom - Action Fraud
Spain - Policía Nacional
France - Ministère de l'Intérieur
Germany - Polizei
Italy - Polizia di Stato
The Netherlands - Politie
Poland - Policja
Portugal - Polícia Judiciária
Isolating the infected device:
Some ransomware-type infections are designed to encrypt files within external storage devices, infect them, and even spread throughout the entire local network. For this reason, it is very important to isolate the infected device (computer) as soon as possible.
Step 1: Disconnect from the internet.
The easiest way to disconnect a computer from the internet is to unplug the Ethernet cable from the motherboard, however, some devices are connected via a wireless network and for some users (especially those who are not particularly tech-savvy), disconnecting cables may seem troublesome. Therefore, you can also disconnect the system manually via Control Panel:
Navigate to the "Control Panel", click the search bar in the upper-right corner of the screen, enter "Network and Sharing Center" and select search result: 
Click the "Change adapter settings" option in the upper-left corner of the window: 
Right-click on each connection point and select "Disable". Once disabled, the system will no longer be connected to the internet. To re-enable the connection points, simply right-click again and select "Enable". 
Step 2: Unplug all storage devices.
As mentioned above, ransomware might encrypt data and infiltrate all storage devices that are connected to the computer. For this reason, all external storage devices (flash drives, portable hard drives, etc.) should be disconnected immediately, however, we strongly advise you to eject each device before disconnecting to prevent data corruption:
Navigate to "My Computer", right-click on each connected device, and select "Eject": 
Step 3: Log-out of cloud storage accounts.
Some ransomware-type might be able to hijack software that handles data stored within "the Cloud". Therefore, the data could be corrupted/encrypted. For this reason, you should log-out of all cloud storage accounts within browsers and other related software. You should also consider temporarily uninstalling the cloud-management software until the infection is completely removed.
Identify the ransomware infection:
To properly handle an infection, one must first identify it. Some ransomware infections use ransom-demand messages as an introduction (see the WALDO ransomware text file below).
This, however, is rare. In most cases, ransomware infections deliver more direct messages simply stating that data is encrypted and that victims must pay some sort of ransom. Note that ransomware-type infections typically generate messages with different file names (for example, "_readme.txt", "READ-ME.txt", "DECRYPTION_INSTRUCTIONS.txt", "DECRYPT_FILES.html", etc.). Therefore, using the name of a ransom message may seem like a good way to identify the infection. The problem is that most of these names are generic and some infections use the same names, even though the delivered messages are different and the infections themselves are unrelated. Therefore, using the message filename alone can be ineffective and even lead to permanent data loss (for example, by attempting to decrypt data using tools designed for different ransomware infections, users are likely to end up permanently damaging files and decryption will no longer be possible even with the correct tool).
Another way to identify a ransomware infection is to check the file extension, which is appended to each encrypted file. Ransomware infections are often named by the extensions they append (see files encrypted by Qewe ransomware below).
This method is only effective, however, when the appended extension is unique - many ransomware infections append a generic extension (for example, ".encrypted", ".enc", ".crypted", ".locked", etc.). In these cases, identifying ransomware by its appended extension becomes impossible.
One of the easiest and quickest ways to identify a ransomware infection is to use the ID Ransomware website. This service supports most existing ransomware infections. Victims simply upload a ransom message and/or one encrypted file (we advise you to upload both if possible).
The ransomware will be identified within seconds and you will be provided with various details, such as the name of the malware family to which the infection belongs, whether it is decryptable, and so on.
Example 1 (Qewe [Stop/Djvu] ransomware):
Example 2 (.iso [Phobos] ransomware):
If your data happens to be encrypted by ransomware that is not supported by ID Ransomware, you can always try searching the internet by using certain keywords (for example, a ransom message title, file extension, provided contact emails, crypto wallet addresses, etc.).
Search for ransomware decryption tools:
Encryption algorithms used by most ransomware-type infections are extremely sophisticated and, if the encryption is performed properly, only the developer is capable of restoring data. This is because decryption requires a specific key, which is generated during the encryption. Restoring data without the key is impossible. In most cases, cybercriminals store keys on a remote server, rather than using the infected machine as a host. Dharma (CrySis), Phobos, and other families of high-end ransomware infections are virtually flawless, and thus restoring data encrypted without the developers' involvement is simply impossible. Despite this, there are dozens of ransomware-type infections that are poorly developed and contain a number of flaws (for example, the use of identical encryption/decryption keys for each victim, keys stored locally, etc.). Therefore, always check for available decryption tools for any ransomware that infiltrates your computer.
Finding the correct decryption tool on the internet can be very frustrating. For this reason, we recommend that you use the No More Ransom Project and this is where identifying the ransomware infection is useful. The No More Ransom Project website contains a "Decryption Tools" section with a search bar. Enter the name of the identified ransomware, and all available decryptors (if there are any) will be listed.
Restore files with data recovery tools:
Depending on the situation (quality of ransomware infection, type of encryption algorithm used, etc.), restoring data with certain third-party tools might be possible. Therefore, we advise you to use the Recuva tool developed by CCleaner. This tool supports over a thousand data types (graphics, video, audio, documents, etc.) and it is very intuitive (little knowledge is necessary to recover data). In addition, the recovery feature is completely free.
Step 1: Perform a scan.
Run the Recuva application and follow the wizard. You will be prompted with several windows allowing you to choose what file types to look for, which locations should be scanned, etc. All you need to do is select the options you're looking for and start the scan. We advise you to enable the "Deep Scan" before starting, otherwise, the application's scanning capabilities will be restricted.
Wait for Recuva to complete the scan. The scanning duration depends on the volume of files (both in quantity and size) that you are scanning (for example, several hundred gigabytes could take over an hour to scan). Therefore, be patient during the scanning process. We also advise against modifying or deleting existing files, since this might interfere with the scan. If you add additional data (for example, downloading files/content) while scanning, this will prolong the process:
Step 2: Recover data.
Once the process is complete, select the folders/files you wish to restore and simply click "Recover". Note that some free space on your storage drive is necessary to restore data:
Create data backups:
Proper file management and creating backups is essential for data security. Therefore, always be very careful and think ahead.
Partition management: We recommend that you store your data in multiple partitions and avoid storing important files within the partition that contains the entire operating system. If you fall into a situation whereby you cannot boot the system and are forced to format the disk on which the operating system is installed (in most cases, this is where malware infections hide), you will lose all data stored within that drive. This is the advantage of having multiple partitions: if you have the entire storage device assigned to a single partition, you will be forced to delete everything, however, creating multiple partitions and allocating the data properly allows you to prevent such problems. You can easily format a single partition without affecting the others - therefore, one will be cleaned and the others will remain untouched, and your data will be saved. Managing partitions is quite simple and you can find all the necessary information on Microsoft's documentation web page.
Data backups: One of the most reliable backup methods is to use an external storage device and keep it unplugged. Copy your data to an external hard drive, flash (thumb) drive, SSD, HDD, or any other storage device, unplug it and store it in a dry place away from the sun and extreme temperatures. This method is, however, quite inefficient, since data backups and updates need to be made regularly. You can also use a cloud service or remote server. Here, an internet connection is required and there is always the chance of a security breach, although it's a really rare occasion.
We recommend using Microsoft OneDrive for backing up your files. OneDrive lets you store your personal files and data in the cloud, sync files across computers and mobile devices, allowing you to access and edit your files from all of your Windows devices. OneDrive lets you save, share and preview files, access download history, move, delete, and rename files, as well as create new folders, and much more.
You can back up your most important folders and files on your PC (your Desktop, Documents, and Pictures folders). Some of OneDrive’s more notable features include file versioning, which keeps older versions of files for up to 30 days. OneDrive features a recycling bin in which all of your deleted files are stored for a limited time. Deleted files are not counted as part of the user’s allocation.
The service is built using HTML5 technologies and allows you to upload files up to 300 MB via drag and drop into the web browser or up to 10 GB via the OneDrive desktop application. With OneDrive, you can download entire folders as a single ZIP file with up to 10,000 files, although it can’t exceed 15 GB per single download.
OneDrive comes with 5 GB of free storage out of the box, with an additional 100 GB, 1 TB, and 6 TB storage options available for a subscription-based fee. You can get one of these storage plans by either purchasing additional storage separately or with Office 365 subscription.
Creating a data backup:
The backup process is the same for all file types and folders. Here’s how you can back up your files using Microsoft OneDrive
Step 1: Choose the files/folders you want to backup.
Click the OneDrive cloud icon to open the OneDrive menu. While in this menu, you can customize your file backup settings.
Click Help & Settings and then select Settings from the drop-down menu.
Go to the Backup tab and click Manage backup.
In this menu, you can choose to backup the Desktop and all of the files on it, and Documents and Pictures folders, again, with all of the files in them. Click Start backup.
Now, when you add a file or folder in the Desktop and Documents and Pictures folders, they will be automatically backed up on OneDrive.
To add folders and files, not in the locations shown above, you have to add them manually.
Open File Explorer and navigate to the location of the folder/file you want to backup. Select the item, right-click it, and click Copy.
Then, navigate to OneDrive, right-click anywhere in the window and click Paste. Alternatively, you can just drag and drop a file into OneDrive. OneDrive will automatically create a backup of the folder/file.
All of the files added to the OneDrive folder are backed up in the cloud automatically. The green circle with the checkmark in it indicates that the file is available both locally and on OneDrive and that the file version is the same on both. The blue cloud icon indicates that the file has not been synced and is available only on OneDrive. The sync icon indicates that the file is currently syncing.
To access files only located on OneDrive online, go to the Help & Settings drop-down menu and select View online.
Step 2: Restore corrupted files.
OneDrive makes sure that the files stay in sync, so the version of the file on the computer is the same version on the cloud. However, if ransomware has encrypted your files, you can take advantage of OneDrive’s Version history feature that will allow you to restore the file versions prior to encryption.
Microsoft 365 has a ransomware detection feature that notifies you when your OneDrive files have been attacked and guide you through the process of restoring your files. It must be noted, however, that if you don’t have a paid Microsoft 365 subscription, you only get one detection and file recovery for free.
If your OneDrive files get deleted, corrupted, or infected by malware, you can restore your entire OneDrive to a previous state. Here’s how you can restore your entire OneDrive:
1. If you're signed in with a personal account, click the Settings cog at the top of the page. Then, click Options and select Restore your OneDrive.
If you're signed in with a work or school account, click the Settings cog at the top of the page. Then, click Restore your OneDrive.
2. On the Restore your OneDrive page, select a date from the drop-down list. Note that if you're restoring your files after automatic ransomware detection, a restore date will be selected for you.
3. After configuring all of the file restoration options, click Restore to undo all the activities you selected.
The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups.
Frequently Asked Questions (FAQ)
How was my computer hacked and how did hackers encrypt my files?
Cybercriminals employ diverse methods to infect computers, often deceiving users through malicious attachments or misleading links in emails, pirated software, downloads from untrustworthy sources, and malicious advertisements. Additionally, they capitalize on vulnerabilities in outdated software to gain unauthorized access. Their tactics involve manipulating users into unwittingly taking actions that result in malware infections.
How to open ".back" files?
Your files have undergone encryption due to a ransomware infection, requiring a decryption process to restore access to the files.
Where should I look for free decryption tools for Back ransomware?
In case of a ransomware attack you should check the No More Ransom project website (more information above).
I can pay you a lot of money, can you decrypt files for me?
Our team does not provide this service. Typically, decrypting files encrypted by ransomware involves the cooperation of the developers or operators unless vulnerabilities in the ransomware are identified. It is essential to exercise caution when considering third-party services claiming to offer paid decryption, as these entities may be intermediaries or scammers.
Will Combo Cleaner help me remove Back ransomware?
Combo Cleaner is designed to conduct thorough scans on your computer, aiming to detect and remove any active ransomware infections. It is crucial to acknowledge that while employing an antivirus program like Combo Cleaner is a fundamental aspect of addressing ransomware, these security tools do not possess the capability to decrypt files that have already undergone encryption.
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