Remove Gusau Ransomware (.gusau File Decryption)

The name Gusau ransomware was derived from the files that were infected by the same threat. It is infamous for labeling all contaminated data with GUSAU extension aside from making it inoperable. This ransom virus originates from the STOP malware group that is very notorious with its file-locking activities and takes advantage of this circumstance to rip off money from victims.

Gusau ransomware utilizes a variety of attack campaign to spread the malicious code over the internet. Common and mostly observed deployment scheme by attackers are spam email messages and malicious advertising campaign. Through this method, Gusau reaches target computer through misinformation. The virus will disguise as either valuable file or application, which easily entices users to execute by presenting deceitful beneficial gains.

The moment Gusau is executed, it commence a continuous chain of disastrous event on the computer that will start with the deactivation of system security and blocking of outgoing internet traffic to specific anti-virus vendors and computer security portals. Gusau will continue to operate maliciously inside the computer until it reaches the final stage of the attack, which is file encryption.

The last phase is the most damaging sequence because it is on this part that Gusau will search the infected computer for common files and encrypts them with a complex algorithmic pattern. Files typically hunt down by Gusau are Documents, Presentations, Spreadsheets, Audios, Video, Photos, Images, Archives, Drawings, and so on. Infected files are easily recognizable by the appended GUSAU extension and to site an example, resume.doc will become resume.doc.gusau after the encryption process.

Image of Gusau Ransomware Files

After successful encryption of user’s data, Gusau will leave a ransom note stating that there is no other solution but to pay the attacker in order for victims to recover all infected files. Below is an excerpt from the ransom note and next segment is a topic that can help victims with the proper ways of removing Gusau ransomware.

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.
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.

Backup your files

One important step before proceeding with the procedures below is to backup your files. Ransomware attacks are not the same. Each has its own unique set of payloads, aside from encrypting the files with a complex method. Others tend to delete the infected files after a certain period, while others keep them concealed in hidden places. In addition, ransomware decryption tools are not guaranteed to be perfect, and there are instances where files suffer from damages during the decryption process.

So, it is better to create a backup copy of your entire Gusau-encrypted files right now.

Gusau Ransomware Removal Guide

The first thing to do is remove the Gusau 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 with the Gusau ransomware virus is dangerous to the system because it can inject files that run each time Windows starts. To prevent malicious files from loading, the Windows operating system must run with minimal processes, and this can be done through SafeMode With Networking.

Step 1 : Scan the PC with Combo Cleaner for Windows

Combo Cleaner is a trusted PC security and optimization tool equipped with a powerful virus and malware detection engine. This program can get rid of adware like Gusau 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 database file; please wait for this process to complete.

6. To begin checking for threats like Gusau, click on the Start Scan button. Wait for this scan to finish.

Screenshot of Combo Cleaner PC

7. At the end of the scan process, click on Remove all threats to delete Gusau hijacker, including all malicious objects from the computer.

To fully optimize the features of antivirus and privacy scanners, users may have to upgrade to the premium version.

Please continue with the succeeding removal procedures if you are comfortable manually getting rid of the threat and malicious items linked to it.

Step 2 : Start Windows in Safe Mode With Networking

The method of running Windows in Safe Mode before running a virus scan is effective in getting rid of Gusau. This process can prevent most viruses and malware from loading, making it easier to detect and remove them.

1. On the Windows Search bar, please type msconfig.

Screenshot of Win 11 Search

2. Select and open System Configutation on the list of found results.

3. Once you are in the System Configuration window, go to the Boot tab.

Screenshot of Msconfig Win 11

4. Under the Boot Options area, please check Safe Boot so that it starts in Safe Mode after restarting.

5. Next, select Network. This will allow Windows to boot in Safe Mode with Networking.

6. Lastly, click on Apply and OK to save the changes.

7. Please restart Windows.

Do not forget to restore the normal boot process of Windows after running the virus scan. Simply repeat the method above, and this time, uncheck the Safe Boot option to run Windows normally.

Step 3 : Scan the Computer with Sophos Home Antivirus

Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Gusau virus. Aside from our suggested tool, you may also run your own security program.

To remove Gusau ransomware automatically, scanning the computer with this efficient antivirus tool is suggested. This scanner does not just uncover known threats like viruses or malware, it is also effective in discovering hazardous ransomware like Gusau.

1. Please click on the link below to download the program.

2. After downloading, locate the file SophosInstall.exe in the Downloads folder.

3. Install by double-clicking on the file.

4. If it prompts "Do you want to allow this app to make changes on your device?" please click Yes.

5. Next, it will display the Terms and Conditions page. Click the Install button to begin.

Screenshot of Terms by Sophos Home

6. Run the installation with the default settings. Please note that an internet connection is required in order to download important updates.

7. After finishing the installation, you must login to the dashboard. If you already have a Sophos account, please login. Otherwise, please enter your details and click on the Create Account button.

8. Once you are in the Sophos Home console, click the Scan button to start checking the computer for Gusau components.

Screenshot of Sophos Home

9. Scanning may take a while; please wait for this process to finish.

10. After scanning the computer, Sophos Home will start cleaning or deleting files infected with Gusau.

11. You may now close Sophos Home. The computer is now free from Gusau, as well as associated malware and viruses.

The above procedures should have totally eliminated Gusau ransomware. However, if you find that there are still remnants of the virus, please proceed to the next steps below.

Step 4 : Double Check with Windows Security Apps

Microsoft Windows has a built-in security application that you can use to double-check if your computer is still infected with Gusau. For Windows 10/11 users, please run Windows Security.

Windows 10 / 11 Instructions:

Windows Security is a free tool that was built to help you remove Gusau, viruses, and other malicious items from Windows 10/11 systems. Follow these procedures to scan your computer with the tool:

1. Tap or click the Search charm and search for Windows Security

2. Click Open to run the program.

Screenshot of Win 11 Search

3. On the Dashboard, click Virus and threat protection from the sidebar.

Screenshot of Win 11 Virus Protection

4. On the right panel, click on Scan Options to see different levels of checking the computer.

5. Next, please select Full Scan button.

Screenshot of Full Scan Win 11

6. Lastly, click on the Scan now button to start scanning for the presence of Gusau. The process may take a while to complete.

7. After the scan, Delete/Quarantine identified threats, whether they were relevant to Gusau or not. You may now restart Windows to complete the virus removal process.

For Windows 8.1 and Windows 7, you can scan the computer for free with the Microsoft Malicious Software Removal Tool (MSRT 64-Bit). It is a stand-alone virus scanner tool that targets prevalent malware groups.

Recover Files from Gusau Ransomware Infection

In this section, we will provide ways to decrypt files infected with Gusau 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 a new and more suitable decryption tool becomes available.

Find a suitable Gusau decryption tool from Emsisoft

This service from Emsisoft is helpful in unlocking encrypted files without paying a ransom. The page provides a list of ransomware decryption tools. All you have to do is look for the specific tool and start recovering the Gusau-encrypted file.

How to protect the computer from Gusau ransomware?

After the ransomware is removed, it is important to prevent similar incidents from happening again. To effectively protect the computer, the user must know how Gusau ransomware was able to infect it. To minimize the possibility of infection, staying away from the common sources of this virus is crucial.

How does ransomware infect your computer?

The method of infecting the computers was found to be similar to that of other common viruses. Ransomware like Gusau is seen to have efficient deployment via spam email messages, web injectors, malicious software installers, misleading online advertisements, and Trojan Downloaders.

Once the virus is executed, it immediately infects the system. Then, Gusau ransomware communicates with a remote server so that a unique key can be generated for a specific computer. After acquiring the key, it starts to decrypt target files using a complex method that is almost unbreakable. In the final stage of the attack, Gusau ransomware demands ransom money in exchange for the decryption tool. To further understand the attack scheme, we have included an infographic below.

Infographic image of ransomware attack stages
You can print, download, or share the infographic by clicking the image.

What are the essential things to do?

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 10/11 users, aside from protecting the computer using anti-virus or anti-malware programs, one way to protect against ransomware attacks is by using Controlled Folder Access. This feature of Windows Defender Security Center may not prevent the Gusau ransomware infection, but it can protect folders and files in general. Follow the steps to enable Controlled Folder Access in Windows 10/11.

1. Go to Windows Search and type Windows Security.

Screenshot of Win 11 Search

2. Open Windows Security to see all the options.

3. Click Virus and Threat Protection, either on the sidebar or on the main panel.

Screenshot of Ransomware Protection

4. Scroll down to the "Ransomware Protection" area, and click on Manage Ransomware Protection.

5. In the "Controlled Folder Access" section, turn the slider to On. This will enable the feature and protect the folder against Gusau virus or any type of ransomware.

Screenshot of Controlled Folder

6. Click on Protected Folders to see the list of included folders. If Windows displays a message, "Do you want to allow this app to make changes to your device?" please click Yes to proceed.

Screenshot of Protected Folder

7. Click on the Add a Protected Folders button to include additional folders. Make sure that folders with important files are included in the list.

Troubleshooting Guide

Certain programs may be blocked by the Controlled Folder Access feature. To fix the issue, simply have the specific program whitelisted.

1. Under the "Controlled Folder Access" section, click Allow an app through Controlled folder access.

2. If Windows displays the message "Do you want to allow this app to make changes to your device?" click Yes to continue.

3. Next, click the Add an allowed app button.

Screenshot of Allowing App

4. Lastly, click on the Recently blocked app and remove the program from the list of blocked applications.

This Controlled Folder Access feature is one way to protect files against Gusau ransomware. Other important things to do to keep files safe against ransomware are early prevention, like keeping programs updated, installing an efficient security program, and doing regular file backups on a separate media drive.

About the author

1 thought on “Remove Gusau Ransomware (.gusau File Decryption)”

  1. Decrypted 3955 files!
    Skipped 33029 files.

    [!] No keys were found for the following IDs:
    [*] ID: OfxjjdewFBttrOlSAqGGwlqHmGhH6qGnPAy3pvvY (.gusau )
    [*] ID: 68O9eTFDNbn8z2O956vweaL1v2GY5gvWBYMKcmt1 (.gusau )
    [*] ID: OfxjjdewFBttrOlSAqGGwlqHmGhH6qGnPAy3pvvY (.xml )
    [*] ID: OfxjjdewFBttrOlSAqGGwlqHmGhH6qGnPAy3pvvY (.docx )
    [*] ID: 68O9eTFDNbn8z2O956vweaL1v2GY5gvWBYMKcmt1 (.log )
    [*] ID: 68O9eTFDNbn8z2O956vweaL1v2GY5gvWBYMKcmt1 (.dat )
    Please archive these IDs and the following MAC addresses in case of future decryption:
    [*] MACs: 74:27:EA:B3:88:13, 48:D2:24:22:48:F9
    This info has also been logged to STOPDecrypter-log.txt

    Please help.

Leave a Comment

Your email address will not be published. Required fields are marked *