What is Oonn file extension
.Oonn file extension is an extension that is used by the 245th version of the STOP ransomware. Like other ransomware, Oonn virus is created to encrypt the victim’s files, and then demand a ransom for decrypting them. Fortunately, there is a free Oonn File Decrypt Tool, which in some cases can decrypt the encrypted files. Oonn File Decrypt Tool is a free software that can help ransomware victims decrypt .oonn files. In addition to the decryptor, there are several more methods, each of which can help restore the contents of encrypted files. Read more about this, as well as how to remove Oonn ransomware and protect your computer from such ransomware below.
Screenshot of files encrypted by Oonn virus (‘.oonn’ file extension)
What is Oonn ransomware
Oonn ransomware is new malware that belongs to the category of STOP (Djvu) ransomware. According to security researchers, this malware is not much different from previous versions of STOP ransomware, such as Nile and Kook that were discovered earlier. The ransomware virus is spread by websites offering to download freeware, key generators, activators, cracked games, torrents and so on.
Upon execution, Oonn creates a folder in the Windows system directory where it places a copy of itself and changes some Windows settings so that it starts up every time the computer is restarted or turned on. The virus collects information about the victim’s computer and then tries to establish a connection with its command server (C&C). If the connection has been established, then it sends information about the infected computer to the server, and in response receives the encryption key (the so-called ‘online key’) and additional commands and malware that must be executed on the victim’s computer. If the virus could not establish a connection with its command server, then it uses a fixed key (the so-called ‘offline key’).
Oonn virus encrypts files using a strong encryption algorithm and a long key (‘offline key’ or ‘online key’, as described above). The virus tries to encrypt as many files as possible, for this it only encrypts the first 154kb of the contents of each file and thus significantly speeds up the encryption process. Oonn has the ability to encrypt files on all drives connected to the computer: internal hard drives, flash USB disks, network storage, and so on. It skips without encryption: files located in the Windows system directories, files with the extension .dll, .lnk, .ini, .bat, .sys and files with the name ‘_readme.txt’. The remaining files located on the victim’s computer can be encrypted. For example, the following file types may be the target of ransomware attack:
.xlsm, .ztmp, .dxg, .zdb, .upk, .3fr, .wma, .sql, .kdb, .ods, .lbf, .wotreplay, .fos, .wbz, .js, .gho, .mrwref, .sid, .qic, .css, .xlgc, .webdoc, wallet, .pfx, .0, .db0, .bc7, .wmo, .indd, .itl, .wps, .odm, .cas, .pef, .wmd, .xll, .png, .bik, .dcr, .zip, .doc, .rgss3a, .vpk, .3dm, .rim, .sidd, .raw, .odb, .fpk, .xbdoc, .mlx, .wpb, .mp4, .wbm, .arw, .qdf, .xml, .wdb, .wp, .bsa, .cer, .wsc, .wpe, .xyw, .zif, .rar, .syncdb, .yml, .zip, .xld, .xlsm, .snx, .p12, .ysp, .rwl, .wma, .vfs0, .t12, .ybk, .sav, .jpg, .itdb, .hvpl, .wav, .m4a, .layout, .epk, .wp5, .blob, .mdbackup, .xlsx, .sie, .wp4, .wm, .apk, .forge, .xf, .odc, .wmf, .wbc, .svg, .vcf, .dba, .avi, .py, .wri, .t13, .2bp, .dbf, .wcf, .ntl, .wgz, .icxs, .map, .pdd, .xmind, .mpqge, .x3f, .mov, .sb, .mdf, .pak, .pst, .ws, .xbplate, .psd, .z, .arch00, .m2, .fsh, .ibank, .sidn, .raf, .kdc, .zabw, .x, .dmp, .odt, .ptx, .xy3, .re4, .m3u, .xlsb, .menu, .gdb, .wsd, .xmmap, .r3d, .vtf, .nrw, .pptm, .xar, .mdb, .pptx, .cdr, .itm, .docx, .zw, .odp, .orf, .dng, .hkdb, .wpg, .wpa, .wpd, .wpd, .rtf, .ltx, .yal, .z3d, .xlk, .1, .wbk, .tor, .jpeg, .pem, .wp7, .wdp, .ai, .wbd, .xwp, .erf, .cr2, .lvl, .wpt, .srw, .docm, .xx, .3ds, .bkp, .cfr, .xdb, .litemod, .wsh, .bkf, .jpe, .sum, .rw2, .ppt, .wire, .srf, .esm, .vpp_pc, .xpm, .ff, .y, .der, .asset, .mcmeta, .sis, .p7c, .txt, .7z, .w3x, .wpw, .kf, .tax, .bay, .bar, .wp6, .wbmp, .xlsx, .vdf, .mddata, .sr2, .wmv, .eps, .das, .hplg, .accdb, .xls, .x3d, .dwg, .rb, .wmv, .mef, .crw, .zi, .p7b, .pdf
The Oonn ransomware encrypts file-by-file. Each file that has been encrypted will be renamed, the .oonn extension will be added at the end of its name. Thus, it marks all encrypted files. In every directory where there is at least one encrypted file, the virus places a file named ‘_readme.txt’. The file contains a message from Oonn authors. An example of the contents of this file is given below.
Screenshot of the contents of ‘_readme.txt’ file (Oonn ransom note)
This message says that all files on the computer are encrypted and the only way to decrypt them is to buy a key and a decryptor from the authors of Oonn virus. That is, criminals demand a ransom for unlocking the victim’s files. The size of the ransom is $980, but if the victim is ready to pay the ransom within 72 hours, then its size is halved to $490. Attackers offer victims to verify that encrypted files can be decrypted. To do this, the victim must send them a small file to one of the email addresses specified in the ‘_readme.txt’ file. Of course, it is obvious that a single decrypted file cannot guarantee that after paying the ransom, the criminals will provide the victim with a working key and decryptor.
Threat Summary
| Name | Oonn ransomware, Oonn file virus |
| Type | Ransomware, Crypto virus, Crypto malware, File locker, Filecoder |
| Encrypted files extension | .oonn |
| Ransom note | _readme.txt |
| Contact | helpmanager@mail.ch, restoremanager@airmail.cc |
| Ransom amount | $980,$490 in Bitcoins |
| Detection Names | W32.AIDetectVM.malware2, Win32/GenKryptik.EPZI, Trojan.TR/AD.InstaBot.joxan, UDS:DangerousObject.Multi.Generic, Malware.Heuristic!ET#78% (RDMK:cmRtazqdNDRqP0DAJVPiKqMXuZyz), FileRepMalware |
| Symptoms | Your personal files fail to open. Odd, new or missing file extensions. Your file directories contain a ‘ransom note’ file that is usually a .html, .jpg or .txt file. Your desktop is locked with a message about How to pay to unlock your system. |
| Distribution methods | Malicious e-mail spam. Malicious downloads that happen without a user’s knowledge when they visit a compromised website. Social media, like web-based instant messaging applications. Torrent webpages. |
| Removal | Oonn ransomware removal guide |
| Decryption | Oonn File Decrypt Tool |
How to remove Oonn ransomware; Recover, Decrypt .oonn files
Security researchers confirm the words of the Oonn ransomware authors. All files with the extension ‘.oonn’ are encrypted and thus cannot be read and used. The only way to decrypt them is to use the key and the decryptor. Fortunately, there is some good news. As we already reported above, Oonn virus belongs to STOP ransomware family, which means that you can use the free decryptor (Oonn File Decrypt Tool) created by Emsisoft to decrypt the encrypted files. Even if the decryptor does not help, there are some alternative ways that can help restore the contents of the encrypted files. To learn more about decrypting files, simply scroll down to section ‘How to decrypt .oonn files’. Read the entire manual carefully. To make it easier for you to follow the instructions, we recommend that you print it or open it on your smartphone.
- How to remove Oonn ransomware virus
- How to decrypt .oonn files
- How to restore .oonn files
- How to protect your PC from Oonn ransomware
How to remove Oonn ransomware virus
Before you start decrypting or recovering .oonn files, you need to remove Oonn ransomware and its autostart entries. This must be done since otherwise the ransomware may re-encrypt the restored files. You can stop the ransomware from working, as it is not difficult to do. Another option is to perform a full system scan using free malware removal tools capable of detecting and removing ransomware infection.
It is very important to scan the computer for malware, as security researchers found that spyware could be installed on the infected computer along with the Oonn ransomware. Spyware is a very dangerous security threat as it is designed to steal the user’s personal information such as passwords, logins, contact details, etc. If you have any difficulty removing the Oonn virus, then let us know in the comments, we will try to help you.
To remove Oonn ransomware, follow the steps below:
- Kill the Oonn ransomware process
- Disable the Oonn ransomware Start-Up
- Delete the Oonn ransomware Task
- Delete the Oonn ransomware File
- Scan computer for malware
Kill the Oonn ransomware process
Press CTRL, ALT, DEL keys together.
Click Task Manager. Select the “Processes” tab, look for something suspicious that is the Oonn ransomware then right-click it and select “End Task” or “End Process” option. If your Task Manager does not open or the Windows reports “Task manager has been disabled by your administrator”, then follow the guide: How to Fix Task manager has been disabled by your administrator.
A process is particularly suspicious: it is taking up a lot of memory (despite the fact that you closed all of your programs, its name is not familiar to you (if you are in doubt, you can always check the program by doing a search for its name in Google, Yahoo or Bing).
Disable the Oonn ransomware Start-Up
Select the “Start-Up” tab, look for something similar to the one shown in the example below, right click to it and select Disable.
Close Task Manager.
Delete the Oonn ransomware Task
Type “Task Scheduler” in the search bar. Click Task Scheduler app in the search results. Click “Task Scheduler Library” in the left panel. On the right panel, right-click to “Time Trigger Task” and select Delete.
Close Task Scheduler.
Delete the Oonn ransomware File
Run Task Manager and select the “Start-Up” tab. Right click to the Oonn ransomware Start-Up entry and select Open File Location as shown below.
A directory containing one file will open in front of you, this file is the Oonn ransomware. It needs to be removed. If you try to delete it immediately, then you will not succeed, since this file is protected from deletion.
To delete this file, you need to do the following. Right-click on the file, select Properties. In the window that opens, select Security tab. Next, click the Advanced button below. A window will open as shown in the following example.
Click Disable inheritance. In the Block inheritance dialog box that opens, select the first item (Convert inherited permissions…) as shown below.
In the Permission entries list, select “Deny Everyone”, click Remove button and then OK. Close the file properties window. You should now be able to remove the Oonn ransomware File. Right-click on the file and select Delete.
Scan computer for malware
Zemana Anti-Malware highly recommended, because it can look for security threats such as the Oonn ransomware, other malicious software and trojans which most ‘classic’ antivirus applications fail to pick up on. Moreover, if you have any Oonn removal problems which cannot be fixed by this tool automatically, then Zemana provides 24X7 online assistance from the highly experienced support staff.
Please go to the link below to download Zemana Free. Save it on your MS Windows desktop or in any other place.
164032 downloads
Author: Zemana Ltd
Category: Security tools
Update: July 16, 2019
Once downloading is finished, close all applications and windows on your machine. Open a directory in which you saved it. Double-click on the icon that’s named Zemana.AntiMalware.Setup as on the image below.
When the install starts, you will see the “Setup wizard” which will help you install Zemana on your personal computer.
Once installation is complete, you will see window as shown in the following example.
Now click the “Scan” button . Zemana Anti Malware will start scanning the whole system to find out the Oonn crypto virus, other kinds of potential threats like malicious software and trojans. A system scan can take anywhere from 5 to 30 minutes, depending on your machine. While the Zemana utility is scanning, you can see how many objects it has identified as being affected by malicious software.
Once the scan get finished, you may check all threats detected on your computer. Once you have selected what you want to delete from your machine press “Next” button.
The Zemana tool will start to delete Oonn crypto malware and other security threats.
In order to be 100% sure that the computer no longer has the Oonn malware, we recommend using the Kaspersky virus removal tool (KVRT). It is free and easy to use. It can detect and remove ransomware, spyware, potentially unwanted applications, worms, trojans, adware software and other malware. KVRT is powerful enough to find and uninstall malicious registry entries and files that are hidden on the PC system.
Download Kaspersky virus removal tool (KVRT) from the link below.
129056 downloads
Author: Kaspersky® lab
Category: Security tools
Update: March 5, 2018
When the download is complete, double-click on the KVRT icon. Once initialization procedure is done, you’ll see the KVRT screen such as the one below.
Click Change Parameters and set a check near all your drives. Click OK to close the Parameters window. Next press Start scan button to locate the Oonn crypto malware and other known infections. Depending on your system, the scan can take anywhere from a few minutes to close to an hour. When a malware, adware or potentially unwanted applications are detected, the number of the security threats will change accordingly. Wait until the the checking is complete.
When the system scan is complete, you may check all threats found on your computer as displayed in the figure below.
You may remove threats (move to Quarantine) by simply click on Continue to begin a cleaning task.
How to decrypt .oonn files
As we already reported above, files with .oonn extension are files that have been encrypted by the Oonn ransomware. Their contents will remain locked until decrypted using the decryptor and the key. Fortunately, there is a free Oonn File Decrypt Tool that can decrypt .oonn files. Below we provide instructions on where to download and how to use Oonn File Decrypt Tool.
Oonn File Decrypt Tool (STOP Djvu decryptor)
To decrypt .oonn files, use Oonn File Decrypt Tool
- Download Oonn File Decrypt Tool from the following link.
STOP Djvu decryptor - Scroll down to ‘New Djvu ransomware’ section.
- Click the download link and save the decrypt_STOPDjvu.exe file to your desktop.
- Run decrypt_STOPDjvu.exe, read the license terms and instructions.
- On the ‘Decryptor’ tab, using the ‘Add a folder’ button, add the directory or disk where the encrypted files are located.
- Click the ‘Decrypt’ button.
Unfortunately, at the moment, Oonn File Decrypt Tool is able to decrypt only files encrypted with an offline key, as Emsisoft found a way to obtain this key. Files encrypted with an online key cannot yet be decrypted. The online key is unique to each infected computer, and at the moment there is no way to find this key. Of course, the Oonn ransomware authors own this key, but we do not think that paying a ransom is the right way to decrypt .oonn files. In the case when the files are encrypted with an online key, there is a chance to restore the encrypted files using alternative methods, which are described below.
How to find out which key was used to encrypt files
Since Oonn File Decrypt Tool only decrypts files encrypted with the offline key, each ransomware victim needs to find out which key was used to encrypt the files. Determining the type of key used is not difficult. Below we give two ways. Use any of them. We recommend using the second method, as it is more accurate.
Personal ID is highlighted here
Find out the type of key using ‘_readme.txt’ file
- Open the ransom demand message (‘_readme.txt’ file).
- Scroll down to the end of the file.
- There you will see a line with the text ‘Your personal ID’.
- Below is a line of characters that starts with ‘0245’ – this is your personal id.
Find out the type of key using ‘PersonalID.txt’ file
- Open disk C.
- Open directory ‘SystemID’.
- Open file named ‘PersonalID.txt’. This file lists “Personal ID”s that match the keys that the virus used to encrypt files.
The ‘Personal ID’ is not a key, it is an identifier related to a key that was used to encrypt files. If the ID ends with ‘t1’, then the files are encrypted with an offline key. If the ID does not end with ‘t1’, Oonn ransomware used an online key. If you could not figure out how to determine which key was used to encrypt files, then we can help. Just write a request here or in the comments below.
Oonn File Decrypt Tool : “No key for New Variant online ID”
If, when you try to decrypt .oonn files, Oonn File Decrypt Tool reports:
No key for New Variant online ID: *
Notice: this ID appears to be an online ID, decryption is impossible
It means that your files are encrypted with an ‘online key’ and their decryption is impossible, since only the oonn authors have the key necessary for decryption. In this case, you need to use alternative methods listed below to restore the contents of encrypted files.
Oonn File Decrypt Tool : “No key for New Variant offline ID”
If, during decryption of .oonn files, Oonn File Decrypt Tool reports:
No key for New Variant offline ID: *t1
Notice: this ID appears be an offline ID, decryption MAY be possible in the future.
It means the following: your files are encrypted with an ‘offline key’, but the key itself has not yet been obtained by security researchers, in this case, you need to be patient and wait a while, in addition, you can also use alternative ways for recovering encrypted data.
If for some reason you were unable to decrypt the encrypted files, then We recommend to follow the news on our Facebook or YouTube channels. So you ‘ll know right away that it ‘s possible to decrypt .oonn files.
This video step-by-step guide will demonstrate How to remove Oonn ransomware, Decrypt/Recover .oonn files.
How to restore .oonn files
As we mentioned above, in addition to using the Oonn File Decrypt Tool, there are several more methods for recovering encrypted files. These methods do not require the use of a decryptor and a key, and therefore are suitable for all cases when the virus used an online key, and for the case when the virus used an offline key. It is very important to check your computer for malware before you try to recover encrypted files. You must be 100% sure that Oonn virus is completely removed. To scan your computer for ransomware, use free malware removal tools
Use shadow copies to restore .oonn files
The Microsoft Windows has a feature called ‘Shadow Volume Copies’ that can help you to recover .oonn files encrypted by the ransomware. A small tool called ShadowExplorer will allow you to easily access the Shadow copies and restore the encrypted files to their original state. Unfortunately, the ransomware can delete these Shadow copies before it starts encrypting files. Therefore, if ShadowExplorer did not help you, then try another method, which is given below.
First, click the link below, then click the ‘Download’ button in order to download the latest version of ShadowExplorer.
438669 downloads
Author: ShadowExplorer.com
Category: Security tools
Update: September 15, 2019
When downloading is complete, extract the downloaded file to a directory on your computer. This will create the necessary files as displayed in the following example.
Launch the ShadowExplorerPortable program. Now choose the date (2) that you want to restore from and the drive (1) you wish to recover files (folders) from as shown in the figure below.
On right panel navigate to the file (folder) you want to recover. Right-click to the file or folder and click the Export button as displayed on the image below.
And finally, specify a directory (your Desktop) to save the shadow copy of encrypted file and click ‘OK’ button.
This video step-by-step guide will demonstrate How to recover encrypted files using Shadow Explorer.
Restore .oonn files with PhotoRec
The last chance to restore .oonn files to their original state is using data recovery tools. We recommend a program called PhotoRec. It has all the necessary functions to restore the contents of encrypted files. It helped many victims recover data when it seemed like there was no more hope.
Download PhotoRec by clicking on the following link. Save it directly to your Windows Desktop.
Once downloading is complete, open a directory in which you saved it. Right click to testdisk-7.0.win and choose Extract all. Follow the prompts. Next please open the testdisk-7.0 folder as shown on the screen below.
Double click on qphotorec_win to run PhotoRec for MS Windows. It will show a screen as on the image below.
Select a drive to recover such as the one below.
You will see a list of available partitions. Select a partition that holds encrypted documents, photos and music such as the one below.
Click File Formats button and specify file types to restore. You can to enable or disable the restore of certain file types. When this is finished, press OK button.
Next, press Browse button to select where restored personal files should be written, then click Search. We strongly recommend that you save the recovered files to an external drive.
Count of recovered files is updated in real time. All recovered files are written in a folder that you have chosen on the previous step. You can to access the files even if the recovery process is not finished.
When the recovery is complete, click on Quit button. Next, open the directory where recovered files are stored. You will see a contents as shown on the screen below.
All restored files are written in recup_dir.1, recup_dir.2 … sub-directories. If you’re looking for a specific file, then you can to sort your recovered files by extension and/or date/time.
This video step-by-step guide will demonstrate How to recover encrypted files using PhotoRec.
How to protect your PC from Oonn ransomware
Most antivirus programs already have built-in protection system against the crypto virus. Therefore, if your system does not have an antivirus program, make sure you install it. As an extra protection, run the HitmanPro.Alert. All-in-all, HitmanPro.Alert is a fantastic tool to protect your system from any ransomware. If ransomware is detected, then HitmanPro.Alert automatically neutralizes malware and restores the encrypted files. HitmanPro.Alert is compatible with all versions of MS Windows operating system from Windows XP to Windows 10.
HitmanPro Alert can be downloaded from the following link. Save it on your Desktop.
After the downloading process is done, open the directory in which you saved it. You will see an icon like below.
Double click the HitmanPro.Alert desktop icon. When the tool is started, you’ll be displayed a window where you can select a level of protection, like below.
Now press the Install button to activate the protection.
Finish words
This guide was created to help all victims of Oonn ransomware virus. We tried to give answers to the following questions: how to remove ransomware; how to decrypt .oonn files; how to recover files, if the Oonn File Decrypt Tool does not help; what is an online key and what is an offline key. We hope that the information presented in this manual has helped you.
If you have questions, then write to us, leaving a comment below. If you need more help with Oonn related issues, go to here.
Hi Bro I Am Encrypted With Online oonn Virus And I Am Not Able To dencrypt Please Help Me Out Bro, Please.
files encrypted with the online key cannot be decrypted, since only the ransomware authors have the decryption key. Try to recover files using ShadowExplorer and PhotoRec.
ShadowExplorer dont show the D driver only C how to show the D
probably no shadow copies were created for the D drive. Use PhotoRec to recover encrypted files.