Oonn ransomware – file-encrypting virus that will ask for a ransom in order to get back your data

Oonn ransomware is a data-locking computer infection that targets users all over the world. First spotted in August 2020, the malware is just another addition to the extensive Djvu ransomware family, which consists of almost 250 variants already. Just as its predecessors such as Nile, Kuus, or Erif, the virus is primarily spread via software cracks and other malicious installers, although it does not mean that other infection means are impossible.
As soon as the Oonn files virus gains access to the machine, it encrypts[1] all personal data (archives, pictures, documents, databases, videos, etc.) on the system and drops _readme.txt ransom note, which serves as a notification from the attackers. Inside, victims are warned that the only way to remove .oonn file virus extension is to pay a ransom of $490/$980 in bitcoin digital currency. However, there might be other options when it comes to file decryption, so contacting the attackers via helpmanager@mail.ch or restoremanager@airmail.cc is not recommended.
| Name | Oonn ransomware, Oonn file virus, .oonn virus |
| Type | File locking virus, cryptomalware |
| Malware family | Djvu/STOP |
| Distribution | Software cracks and pirated program installers |
| Encryption method | RSA is used to encrypt all non-system and non-executable files on the infected machine |
| File extension | .oonn |
| Ransom note | _readme.txt is dropped on several locations on the infected machine |
| Contact | Malicious actors ask users to email them via helpmanager@mail.ch or restoremanager@airmail.cc for negotiation purposes |
| Malware removal | To completely terminate malware from the infected computer, a full system scan with powerful anti-malware should be performed |
| Data recovery |
The only secure method to recover files safely is by copying them from backups. Other options include:
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| Windows fix | In case ransomware corrupted some of the system files, it might cause serious performance issues (crashes, lag, errors, etc.). In such a case, we recommend scanning the device with FortectIntego after an infection is eliminated |
As previously mentioned, Oonn ransomware is mainly spread via contaminated executables that can be downloaded from dangerous sources, such as torrent sites. Despite this distribution method being primitive as it does not require complex usage of various features (in contrary to exploit kits and similar), threat actors behind the strain are infecting hundreds of users each day, and are releasing new variants on a regular basis. Currently, Djvu is the most prolific crypto-malware that targets home consumers.
As soon as the virus gains access to the device, it first shows a pop-up that looks identical to that of a Windows update prompt. This is done in order to mislead users and prevent them from terminating the encryption process. This way, the attackers behind the Oonn virus can cause maximum damage to victims and lock the files that are most important to them, including PDF, .jpg, .zip, .doc, .mpg, and many others.
However, since the main goal of Oonn ransomware is not to corrupt Windows system (although this might occur unintentionally – this can lead to the need of OS reinstallation – we recommend attempting a fix with tools such as FortectIntego) but lock files instead, it skips system and some of the other important files. Besides, many ransomware self-delete after the data encryption is complete, although Oonn ransomware removal might still be needed due to several reasons:
- Djvu variants are known to be distributed along with other malware, such as banking trojan[3] AZORult;
- File locking virus might install the data-stealing module into Google Chrome, Mozilla Firefox, MS Edge, or another web browser;
- If not deleted, it might re-encrypt all files that might have been recovered in different ways.
Also, Oonn files virus might also prevent access to security-related websites that seek to help victims of ransomware. This is done with the help of the Windows “hosts” file, where a set of URLs is held. Since the host's file is not malicious and is a part of any Windows system, the security application can not undo such changes, so you should go to the C:\Windows\System32\drivers\etc\ location and delete the file after you remove Oonn ransomware.

.OONN virus file recovery options
After malware performs the data locking process, users can no longer access .oonn files anymore. Instead, they are presented with a ransom note _readme.txt, which provides the following information:
ATTENTION!
Don't worry, you can return all your files!
All your files like photos, databases, documents and other important are encrypted with strongest encryption and unique key.
The only method of recovering files is to purchase decrypt tool and unique key for you.
This software will decrypt all your encrypted files.
What guarantees you have?
You can send one of your encrypted file from your PC and we decrypt it for free.
But we can decrypt only 1 file for free. File must not contain valuable information.
You can get and look video overview decrypt tool:
hxxps://we.tl/t-NjQb8RxCzz
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:
helpmanager@mail.chReserve e-mail address to contact us:
restoremanager@airmail.ccYour personal ID:
As evident, crooks behind Oonn ransomware virus are willing to provide “test decryption” and even a discount if contact is made within 72 hours of the infection. However, these are all promises that might never be fulfilled, as cybercriminals care little about users' well being, evidently. Thus, if you pay, you might not only lose .oonn files forever but also a significant sum of money.
However, the question remains – how to open .oonn file extension without paying cybercriminals? The answer to this question is not simple, as each case is individual, and consists of many factors.
As a general misconception, users infected with ransomware believe that they can recover .oonn files as soon as they eliminate ransomware from their systems. However, it is important to understand that security software will not allow you to access your locked data, as it is not designed for such a purpose.
Instead, there are several other options that can sometimes be useful when trying to recover Oonn files. Here are a few examples:
- You can attempt to use Emsisoft's decryption tool that might be useful in some cases (i.e., if the virus used an offline ID to lock your files and somebody with the same ID paid criminals and then shared the key with security researchers behind the decryptor);
- Built-in system resources, such as Shadow Volume Copies, might be extremely useful when trying to recover .oonn files. Unfortunately, these backups are deleted by malware if everything goes as planned;
- Third-party recovery solutions can also be used for the data recovery process – they sometimes might help you retrieve at least some portion of lost files.

First, remove Oonn ransomware and only then attempt to recover .oonn files
What most infected users do not comprehend is that file encryption process and malware infection are two separate functions (although the former is not possible without the latter) and that Oonn virus removal will not allow them to open their lost files. Nonetheless, it is important to perform various steps in the correct order, or recovered data might be encrypted repeatedly. It is also important to repair affected system files, so malicious functions get fully disabled. Try FortectIntego as a PC repair tool in such a case.
Before you do anything, you should first copy all the encrypted files to another medium – you can choose online could storage such as OneDrive or back it on a physical external drive. Keep in mind that encrypted .oonn files do not have malicious code in them, so they are safe to transfer.
Once that is complete, you can then remove Oonn ransomware from your machine. For that, download and install powerful security software like SpyHunterCombo Cleaner or MalwarebytesMalwarebytes, and perform a full system scan. Before you scan your device, ensure that anti-malware is fully updated, as it might not recognize the infection right away. Finally, you can then attempt to recover .oonn files with the help of solutions we provide below.
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