A vicious computer virus known as ransomware targets both the Windows operating system and the majority of computer files. Oohu ransomware is a type of malware that belongs to this dangerous class. Computer security researchers discovered a link between it and the STOP/DJVU ransomware clan, which has been inundating the internet recently. Oohu is the 784th version as of a recent count, according to malware researchers who have been observing this virus for quite some time now.
Spreading the virus
Because Oohu is a member of the notorious ransomware gang, it is anticipated that it will have the same characteristics as earlier iterations, such as OOZA amd OOPL. The main method used by these viruses’ creators to propagate the dangerous code is currently spam email campaigns. Second, to find victims, cybercriminals employ file-sharing networks, malicious ads, and virus bundling to infect various freeware programs.
Oohu file encryption
Oohu ransomware begins searching for target files, such as documents, images, spreadsheets, photos, videos, archives, databases, and more, as soon as it gains access to the computer. After that, the virus encrypts user data using a sophisticated technique and adds the Oohu file extension. As a result, following the encryption procedure, a file like pic.jpg will change into pic.jpg.oohu.
Because malware researchers may readily retrieve encrypted files in this scenario, it is lucky for victims if Oohu uses the hard-coded offline keys. Therefore, there is a slim probability that victims will be able to recover their information if Oohu performs file encryption while online and is successful in communicating with the command-and-control server to obtain the special key. This is the rationale for some people turning to the Oohu writers for a transaction and opting to pay a hefty $980 ransom price in exchange for the private key and decryption software.
|Threat Name||Oohu Ransomware, STOP/DJVU|
|Threat Type||Crypto-virus, File Locker, Encryption Virus|
|Ransomware Note File||_readme.txt|
Backup your files
One important step before proceeding with the procedures below is to backup your files. Ransomware are not the same. Each has its unique sets of payloads aside from encrypting the files with complex method. Others tend to delete the infected files after certain period, while others keep them concealed on hidden places. In addition, ransomware decryption tools are not guaranteed to be perfect, there are instances that files suffer from damages during the decryption process.
So, create a backup copy of your entire Oohu encrypted files right now.
Oohu Ransomware Removal Guide
First thing to do is remove the Oohu virus before attempting the decryption. Remember that as long as the ransomware is active, it will repeatedly encrypt the files on the compromised computer.
Infection of Oohu ransom virus is dangerous to the system because it can inject files that runs each time Windows starts. To prevent the malicious files from loading, Windows operating system must run with minimal process and it can be done through SafeMode With Networking.
Quick Fix - Scan the PC with Combo Cleaner for Windows
Combo Cleaner is a trusted PC security and optimization tool equipped with powerful virus and malware detection engine. This program can get rid of ransomware like Oohu through this procedure.
1. Download the application from the following page:
2. Save the file to your preferred location.
3. Double-click the downloaded file CCSetup.exe and install with the default settings.
4. At the end of the setup process, click Finish to run Combo Cleaner.
5. The tool will update the signature file, please wait for this process to complete.
6. To begin checking for threats like Oohu ransomware, click on the Start Scan button. Wait for this scan to finish.
7. At the end of the scan process, click on Remove all threats to delete Oohu ransomware including all malicious objects from the computer.
Free features of Combo Cleaner for Windows include Disk Cleaner, Big Files finder, Duplicate files finder, and Uninstaller. To use antivirus, privacy scanner, and to delete identified threats, users have to upgrade to a premium version.
Please continue with the succeeding removal procedures if your are comfortable to manually get rid of the threat and malicious items linked with it.
Stage 1 : Temporarily Disable System Restore on Windows OS
Because Oohu ransomware and relevant virus is capable of reinstating itself by exploiting the System Restore of Windows, we suggests that you temporary disable System Restore while executing the steps. This option is also helpful to effectively run a full scan on the computer.Do not forget to enable back System Restore after completing the removal of Oohu ransomware. This feature is vital in reinstating the operating system to previous normal working condition in case of problems or conflicts occurs.
Stage 2 : Start Windows in Safe Mode With Networking
Windows 10/11 Guide
1. Click on Windows logo and select Power icon when options pop-ups.
2. Select Restart from the options while pressing Shift key on the keyboard.
3. Choose an Option window will appear, select the Troubleshoot button.
4. On next window, please choose Advanced Option.
5. On Advanced Option window, click on Startup Settings and then, click Restart button to reboot the computer.
6. When Windows boot on Startup Settings, press function key F5 or number 5 on keyboard.
A simpler alternative for Windows 10 users is to scan the computer with Microsoft Defender Offline. This will run a virus scan in the recovery environment.
Windows 8 Guide
1. Click Windows Start icon at the lower left section of the screen.
2. Open Search window and type Advanced in the field. It will open General PC Settings.
3. Click on Advanced Startup and then, click on Restart Now button.
4. Once the computer starts in Advanced Startup option menu, select Troubleshoot.
5. Next, click on Advanced Options to reveal the next section.
6. Click Startup settings and then, click Restart button to boot the PC in Startup Settings.
7. Use function key F5 or number key 5 to Enable Safe Mode with Networking.
Stage 3 : Scan the Computer with Sophos Antivirus
Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Oohu virus. Aside from our suggested tool, you may also run your own security program.
To remove Oohu ransomware automatically, scanning the computer with this efficient anti-malware tool is suggested. This scanner does not just uncover known threats like viruses or malware, it is also effective in discovering hazardous ransomware like Oohu.
1. Download Sophos Virus Removal Tool from the link below. Save the file on your computer where you can easily access it.
2. Once the download completes, browse the location of the file. Double-click to run the program and begin the install process.
3. On first windows of installation wizard, click Next to continue. Then, it will display the program’s License Agreement. You need to Accept the terms in order to proceed. If Windows prompts for User Account Control, please click Yes to proceed.
4. On succeeding windows, click Next or Continue to carry on with the installation. After completing the installation process, Launch Sophos Virus Removal Tool.
5. Internet connection is required when running this virus scanner in order to download important updates. Make sure that everything is up-to-date to effectively remove Oohu ransomware and other relevant viruses.
6. Click the Start Scanning button to inspect the computer. This will check the system for presence of malicious objects, malware, and viruses. The tool reveals items that were found linked to Oohu ransomware and other suspicious entities. Be sure to remove all identified threats.
The above procedures should have totally eliminated Oohu ransomware. However, if you found that there are still remnants of the virus, please proceed to succeeding procedures below.
Stage 4 : Double-check with Microsoft's Malicious Software Removal Tool
1. Download the free scanner called Malicious Software Removal Tool.
2. The tool automatically checks the operating system and suggest appropriate download version. Click on Download button to begin. Save the file to a convenient location, preferably on Desktop.
3. After downloading the file, Windows will prompt that download has completed. Click Run to start scanning for Oohu ransomware. Another option is to browse the location folder and double click on the file to run.
4. The tool will display Welcome screen, click Next. Please note the message "This tool is not a replacement for an antivirus product." You must understand that this program is made specifically to find and remove malware, viruses, Trojans, and other harmful elements on the computer. It was not designed to protect the computer.
5. Next, you will see Scan Type. Please choose Full Scan to ensure that all Oohu ransom virus entities and other harmful files left on the computer will be found and removed. For advanced computer user, you can opt for Customized Scan, if there are other drives or folders you wanted to include in this scan.
6. Full scan may take a while, please wait for Malicious Software Removal Tool to complete the tasks. However, you may cancel the scan anytime by clicking on the Cancel button.
7. After scanning, the tool will reveal all identified threats. There may be other threats that our first scan fails to detect. Please remove/delete all detected items.
8. When removal procedure is complete, you may now close Malicious Software Removal Tool. We hope that Oohu ransomware have been completely deleted from the computer. Please restart Windows to proceed with the normal operation.
Recover Files from Oohu Ransomware Infection
On this section, we will provide ways to decrypt files infected with Oohu ransomware. Aside from dedicated decryption software and common tools, other options for file recovery are provided. As much as we can, we will update this area whenever there is new and more suitable decryption tool was made available.
Decrypting Oohu infected files with Emsisoft Tools
This service from Emsisoft is helpful in unlocking encrypted files without paying the ransom. The page provides the list of ransomware decryption tools. All you have to do is look for the specific tool and start recovering the Oohu encrypted file.
Option 1: Windows Previous Version Tool
Windows has a feature called "Previous Versions." However, this tool is only usable if restore point was made prior to ransomware infection. To use this tool as "recovery option" for files encypted by Oohu virus, please follow these steps:
1. Open My Computer or Windows Explorer.
2. Right-click on the affected files or folders and select Properties. From given tabs, please click on Previous Versions.
3. New window will open display all backup copy of files and folders you wanted to recover. Choose the appropriate file and click on Open, Copy, or Restore. Restoring selected files overwrites the current locked files on the computer. The tool is not actually recovering files encrypted by Oohu ransomware. Instead, it restores files from backup copy.
Option 2: Use ShadowExplorer to restore files encrypted by Oohu Ransomware
Just like Previous Version tool, ShadowExplorer is taking advantage of shadow copy created by Windows. This tool allows you to retrieve older version of files before it was encrypted by Oohu ransomware.
1. Download ShadowExplorer from the official web site.
2. Install the program with the default settings.
3. The program should run automatically after installation. If not, double-click on ShadowExplorer icon.
4. You can see the drop-down list on top of the console. Please select proper drive and the most recent point-in-time shadow copies of files you wish to restore prior to Oohu ransomware infection.
5. Right-click on the Drive, Folder, or File you wish to restore and click Export...
6. Lastly, ShadowExplorer will prompt for location where you want to save the copy of recovered files.
How to protect the computer from Oohu ransomware?
After the removal of the ransomware, it is important to prevent similar incident from happening again. In order to protect the computer effectively, computer user must know how Oohu ransomware was able to infect the computer. To minimize the possible infection, staying away from the common sources of this virus is crucial.
How Oohu ransomware can infect your computer?
The method of infecting the computers was found to be similar as other common viruses. Though, ransomware like Oohu is seen to have efficient deployment via spam email messages, web injectors, malicious software installers, misleading online advertisements, and through another virus infection.
Once the virus is executed, it immediately infects the system. Then, Oohu ransomware communicates to remote server so that unique key can be generated for the specific computer. After acquiring the key, it starts to decrypt target files using a complex method that is almost unbreakable. On the last stage of the attack, Oohu ransomware demands for ransom money as payment for the decryption tool. To further understand the attack scheme, we have included an infographic below.
Securing the computer against ransomware attack
Do a Regular File Back-up - Always backup your data on a separate storage devices such as external hard drives, optical discs, or online backup services.
Keep Your Software Updated - Make sure that you have the latest software updates especially on the operating system. Recent updates often contain vital security patches to help protect the computer against all forms of threats.
Install a Security Program - Protect the computer with effective anti-virus application using efficient real-time scanning. Regularly run a complete scan to check the computer for presence of malware.
Protect your files with Controlled Folder Access (Windows 10/11)
For Windows 10 users, aside from protecting the computer using anti-virus or anti-malware programs, one way to protect against ransomware attack is by using Controlled Folder Access. This feature of Windows Defender Security Center may not prevent the Oohu ransomware infection, but it can protect the folder and files in general. Follow the steps to enable Controlled Folder Access in Windows 10.
1. Go to Windows 10 Taskbar and search for Windows Defender Security Center.
2. Open Windows Defender Security Center and click on Virus & Threat Protection icon.
3. On next window, please click on Ransomware Protection.
4. Under Controlled Folder Access section, switch the slider to On. That will enable the feature and protect the folder against Oohu virus or any type of ransomware.
5. Click on Protected Folderslink to include additional folders. Make sure that folders where important files are located should be included in the list.
Certain programs maybe blocked by Controlled Folder Access feature. To fix the issue, simply have the specific program to be white listed.
1. Under Protected Folders, click Allow an app through controlled folder access.
2. Next, click the Add an allowed app and include the target executable file.
This Controlled Folder Access feature is one way to protect files against Oohu ransomware. Other important things to do in keeping files safe against ransomware is through early prevention like keeping programs updated, install an efficient security program, an do regular file backup on a separate media drive.