Remove Maas Ransomware (Decrypt .maas Files)

By Chona Esjay | Posted on July 7, 2020 |

If computer files are changing to .maas extension type, it implies that system is infected with Maas ransomware. This kind of crypto-virus is another dangerous variant of STOP/DJVU malware. Maas is known for scouting the infected computer for regular files like MS Office data, Open Office, images, photos, videos, archives, databases and so on. It uses a highly complex algorithm when locking the target files and denies users access to it.

How Maas Ransomware Spreads

Attackers have many ways to spread Maas ransomware but the most reliable for these cyber crooks is the use of spam email tactics. They attached Maas virus code to emails and mass-mail it to sets of address book that they have gathered or bought from an underground network. Definitely, Maas may reach the computer but its execution depends on how careless the recipient is.

Other means to distribute Maas ransomware is through pirated version of software. Mass code is incorporated to several cracked software and host them on various file repository sites and torrent networks. In addition, malicious ad campaign is also seen as another channel that rapidly distributes Maas ransomware over the internet. On this tactic, it is in disguise of software update or computer enhancement and security tool that is promoted in a very deceptive way.

Maas File Recovery

After the virus has infected files using a sophisticated encryption technique, it will append them with .maas file extension. The regular photo.jpg will transform into photo.jpg.maas after the encryption process. Then, Maas ransomware leaves a note on the same location as the infected files containing brief description and instructions on file recovery method.

Maas Virus

Similar to older variants as Zida, Moba, and Vawe, Maas ransomware is also demanding a whooping $980 payment for the decryption tool and private key combo. Attackers will never provide the Maas recovery tool for free, however, they are willing to reduce the ransom payment to $490 if victims may be able to communicate with them within the 72 hours period after the initial attack.

So far, there is no other way to fully decrypt Maas infected files. Even the offered solution by attackers does not guarantee to decrypt the entire encrypted files. The worst case is these cyber crooks can always flee without a trace after receiving the payment from their victims. There were reported cases of this incident so be very careful and wise when dealing with the issue.

How to Remove Maas Ransomware

Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Maas 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 Maas 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 Maas’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 Maas 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 Maas 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 Maas ransomware have been completely deleted from the computer. Please restart Windows to proceed with the normal operation.

Stage 3 : Unlocking files with Maas Decryption Tool

Emsisoft Decryptor for STOP Djvu will work only if affected files were encrypted using Offline Keys. Maas ransomware uses the alternate Offline Keys during encryption if there is a problem encountered while communicating to a remote command-and-control server. Follow the guide to start recovering .maas encrypted files.

1. As precautionary measures, we suggest to BACKUP all your .maas encrypted files first on a separate media (USB Drive, Flash Drive, DVD Discs, etc…).

2. Download Emsisoft Decryptor for STOP Djvu from this archive page.

3. Right-click on decrypt_STOPDjvu.exe and click “Run as Administrator“. Windows may prompt “Do you want to allow this app…” just click Yes to continue.

4. By default, the tool will pre-populate the locations where encrypted files were identified. To include other directories, simply click Add Folder button.

5. To start recovering files infected by Maas ransomware, click on Decrypt button to start the procedure. The interface will display status of the current decryption process.


We will update this section once the full decryption tool is on hand. In the meantime, please try other options below if the above procedure is not not effective.

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 Maas 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 Maas 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 Maas 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 Maas 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.

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