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.
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.
How to Remove Gusau Ransomware
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.
Though affected files may be impossible to decrypt due to complexity of the encryption, you can still try recovery method like alternative tool, Shadow Explorer or Previous Version as described below.
Stage 1: Scan the Computer with Anti-Malware Tool
1. Download free anti-malware scanner called MalwareBytes Anti-Malware.
Malwarebytes Anti-Malware Download Link (this will open a new window)
2. After downloading, install the program. It may run automatically or you have to double-click on the downloaded file MBSetup.exe.
3. Carry out the installation with default setup process.
4. After the installation process, click the Get Started button to launch the program.
5. Continue with the prompts until the main program opens.
6. On the main console, click on Scan to run most complete detection method to find hidden objects associated to Gusau ransomware.
7. Scanning may take a while. Please wait until the anti-malware tool is done with the checking.
8. Once the scan has completed, the tool will display the list of detected threats. Remove all identified malicious items and restart the computer if necessary.
Stage 2: Double-check for Gusau’s leftover with Microsoft’s Malicious Software Removal Tool
1. Download the free scanner called Malicious Software Removal Tool.
Malicious Software Removal Tool Download Link (this will open a new window)
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 Gusau 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 Gusau 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 Gusau ransomware have been completely deleted from the computer. Please restart Windows to proceed with the normal operation.
Stage 3 : Unlocking files with Gusau Decryption Tool
So far, this Gusau decryption tool works only for files that were encrypted using offline keys. This happens sometimes if the virus is unable to communicate to remote server to obtain unique keys; instead, it will use offline keys when encrypting files. However, there is a little chance of recovering files using this tool due to limited available offline keys that were integrated with this decryption tool.
For additional information (download link, supported versions, instructions) about StopDecrypter, please proceed to ransomware decryption tool archive page.
If you received a message stating that “No keys were found for the following IDs (.gusau)”, please copy and submit the information to the official download page to include your information (log file) and have it archive in case decryption software becomes available.
We will update this section once the full decryption tool is on hand. In the meantime, please try other options below.
Option 1: Windows Previous Version Tool
Windows Vista and Windows 7 have a feature called Previous Versions. However, this tool is only usable if restore point was made prior to Gusau ransomware infection. To use this tool and recover files affected by the virus, please follow these steps:
1. Open My Computer or Windows Explorer.
2. Right-click on the affected files or folders. From the drop-down list, please click on Restore 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 encrypted files on the computer.
Option 2: Use ShadowExplorer to restore files encrypted by Gusau 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 Gusau 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 Gusau 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.