Oni ransomware - How to remove

This ransomware right here is really dangerous and a little bit different from other ransomware infections we have discovered lately. While targeted mostly against companies and institutions in Japan, Oni can be used either as a ransomware or a wiper. Even though wipers are not really common nowadays, we have recorded a second wiper in two weeks, as two weeks ago we informed our users about Ordinypt ransomware which also can operate as a wiper.

Oni ransomware remove

Infection Process of Oni ransomware

Infection process of Oni ransomware is rather complicated. Usually viruses like this are spread with mal spam campaigns, but this time this are a bit different. First of all, computers are targeted with remote access trojan. If the infiltration of this trojan is successful, it automatically downloads and installs Oni ransomware on the system.

We have already mentioned that Oni ransomware is mostly targeted to Japanese market, thus obviously all phishing letters and ransomware text itself is written in Japanese. RAT (remote access trojan) is distributed as an attachment to the email letter, that is supposed to be a receipt inside the Word document, which should be accessed after opening attached zip file. If you fall for this trick an open the attachment – it’s game over, the trojan will automatically enter your computer.

We can provide you with such in-depth information due to the research performed by cyber security experts from Cybereason:

Once the attackers gained foothold in the victim’s environment, their next step was to compromise critical assets including file servers, application servers and the DC. The attackers managed to move laterally within the internal network through shared network drives and other techniques.

That means Oni ransomware can infect other computers on the same network and this feature only makes it more threatful. it is really confusing whether to call it ransomware or a wiper, because as for know, only cases of removing files from systems have been recorded, but it’s known that Oni can easily lock files by encrytping it. So basically there are two different versions of Oni – one is dedicated to removing files and destroying entire systems, while the other one targets sole users and makes money by encrypting files and demanding for a ransom. All processes of Oni ransomware are really similar to the ones we have seen with GlobeImposter virus. Once files are encrypted, this ransomware will add extension .oni to the end of each encrypted file and create file named “!!!README!!!.html” on every single folder that features encrypted files. Text in the given file is written in Japanese, but keep in mind that Oni ransowmare can attack users absed in other countries too, thus we provide you with the translated version as well:

Important information!

All files are encrypted with RSA – 2048 and AES – 256 ciphers.
Do not worry, you can restore all the files.
We guarantee that all files can be safely restored quickly and safely.
For instructions on recovering files, contact us.
To prove reliability, you can decipher two files for free. Please send us the file and personal ID.
(File size less than 10 MB, no confidential information)

contact information
[email protected]

Original text in Japanese:



[email protected]

As usually, cyber criminals are trying to build confidence by suggesting to send them encrypted file so they could decrypt it and prove that they have the technology to perform it. You are also informed that your files are encrypted with strong RSA – 2048 and AES – 256 cryptographies and encouraged to contact them by email “[email protected]”.

We do not recommend to either contact cyber criminals or try to pay the ransom, because you simply can’t trust cyber criminals – this can easily result in losing your money and not receiving decryption key. Unfortunately, there is no way to decrypt those files encrypted by Oni at the moment, thus the only option to retrieve your files is to perform a system restore.

Finally, if you are looking to remove malicious files of Oni ransomware from your computer and protect your system from malware like this in the future, we recommend to scan it with trustworthy anti-malware application. You can use Spyhunter for this task – both of these applications should deal perfectly with infection like this. Please note that neither of those programs will be able to unlock your files, it’s not a decryptor.

How to recover Oni ransomware encrypted files and remove the virus

Step 1. Restore system into last known good state using system restore

1. Reboot your computer to Safe Mode with Command Prompt:

for Windows 7 / Vista/ XP
  • Start Shutdown RestartOK.
  • Press F8 key repeatedly until Advanced Boot Options window appears.
  • Choose Safe Mode with Command Prompt. Windows 7 enter safe mode

for Windows 8 / 10
  • Press Power at Windows login screen. Then press and hold Shift key and click Restart. Windows 8-10 restart to safe mode
  • Choose TroubleshootAdvanced OptionsStartup Settings and click Restart.
  • When it loads, select Enable Safe Mode with Command Prompt from the list of Startup Settings. Windows 8-10 enter safe mode

2.Restore System files and settings.

  • When Command Prompt mode loads, enter cd restore and press Enter.
  • Then enter rstrui.exe and press Enter again.CMD commands
  • Click “Next” in the windows that appeared. Restore point img1
  • Select one of the Restore Points that are available before Oni ransomware has infiltrated to your system and then click “Next”. Restore point img2
  • To start System restore click “Yes”. Restore point img3

Step 2. Complete removal of Oni ransomware

After restoring your system, it is recommended to scan your computer with an anti-malware program, like Spyhunter and remove all malicious files related to Oni ransomware. You can check other tools here.  

Step 3. Restore Oni ransomware affected files using Shadow Volume Copies

If you do not use System Restore option on your operating system, there is a chance to use shadow copy snapshots. They store copies of your files that point of time when the system restore snapshot was created. Usually Oni ransomware tries to delete all possible Shadow Volume Copies, so this methods may not work on all computers. However, it may fail to do so. Shadow Volume Copies are only available with Windows XP Service Pack 2, Windows Vista, Windows 7, and Windows 8. There are two ways to retrieve your files via Shadow Volume Copy. You can do it using native Windows Previous Versions or via Shadow Explorer. a) Native Windows Previous Versions Right-click on an encrypted file and select PropertiesPrevious versions tab. Now you will see all available copies of that particular file and the time when it was stored in a Shadow Volume Copy. Choose the version of the file you want to retrieve and click Copy if you want to save it to some directory of your own, or Restore if you want to replace existing, encrypted file. If you want to see the content of file first, just click Open.
Previous version
b) Shadow Explorer It is a program that can be found online for free. You can download either a full or a portable version of Shadow Explorer. Open the program. On the left top corner select the drive where the file you are looking for is a stored. You will see all folders on that drive. To retrieve a whole folder, right-click on it and select “Export”. Then choose where you want it to be stored.
Shadow explorer

Step 4. Use Data Recovery programs to recover Oni ransomware encrypted files

There are several data recovery programs that might recover encrypted files as well. This does not work in all cases but you can try this:
  • We suggest using another PC and connect the infected hard drive as slave. It is still possible to do this on infected PC though.
  • Download a data recovery program.
  • Install and scan for recently deleted files. Data Recovery Pro
Note: In many cases it is impossible to restore data files affected by modern ransomware. Thus I recommend using decent cloud backup software as precaution. We recommend checking out Carbonite, BackBlaze, CrashPlan or Mozy Home.

Manual removal

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