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MMUZ ransomware arises from the infamous STOP/DJVU data-encrypting malware group

MMUZ ransomware is a dangerous file-encrypting virus that was recently released by the infamous group known as STOP/DJVU. This virus usually encrypts every file it comes across in any computer it infects and also appends them with .mmuz extension. For illustration, a file formerly known as 1.jpg would eventually become 1.jpg.mmuz and same applies to all data. During the attack, _readme.txt notes will also be dropped in all the folders. These ransom notes are sent by the cybercriminals behind the attack and would contain notifications informing the victim about the development and why they would have to pay ransom notes for them to be given MMUZ decryption tool.

The _readme.txt ransom notes will explain that MMUZ ransomware was able to encrypt all files (i.e. make them unreadable) contained in the infected computer. The affected files include all documents, pictures and every other data that may be very important to the victim. Furthermore, the cybercriminals will brag that since they made use of very strong and peculiar key, there is no way the victim could retrieve their files except they pay ransom as requested by them. To open a channel of communication, they will also drop two email addresses (support@sysmail.ch and supportsys@airmail.cc) which they expect the victim to use in responding to them.

Also included in the ransom note are decryption service prices. The cybercriminals will also emphasize that the specific amount payable by the victim would depend on how soon they’re able to respond. Although the full ransom amount they often request for is $980, but they will tell the victim that only 50% of it could be acceptable provided they can pay within 3 days/72 hours of being notified. In other words, they would now be required to pay $490 but once 72 hours elapses, the ransom fee must be paid 100%.

If the victim replies through any of the email they provided, more conditions will be announced. This time, they will state that payment can only be made by purchasing cryptocurrency that is equivalent to the ransom amount quoted in hard currency and same would be transferred to a particular wallet address that would be provided by them. They consider such an anonymous medium perfect for them since the transactions would remain untraceable. As a way of convincing the victim about their expertise in decrypting files, they may suggest that parts of the encrypted files be sent to them for test decryption. However, they will be quick to add that such parts must not contain any information that could be perceived as important to the victim.

Nevertheless, our team of cybersecurity experts has advised that victims of ransomware should follow the guidelines stipulated by FBI when dealing with cybercriminals, and it clearly says NO TO RANSOM DEMAND. Some of the reasons put forward for such stance are listed below:

• You’re unlikely to retrieve your encrypted files from them even after paying ransom.
• It is against the law to pay ransom to cybercriminals.
• When ransom is paid to cybercriminals, they become more emboldened to victimize others.

Although there are various other reasons why ransom must not be paid and each year, millions of dollars are extorted from victims but such would be curtailed if proactive measures are taken. Furthermore, this virus is also known for dropping Trojans that steal information like VIDAR and AZORULT which can covertly steal vital personal information such as software login credentials, cryptocurrency wallets, banking details, browsing history and passwords etc. Such sensitive details in the hands of cybercriminals could lead to more problems like theft or blackmail.

For those whose computers were infiltrated by this STOP/DJVU variant should remove MMUZ ransomware virus as soon as its presence is noticed. The recommended way to go about it is to set up the infected computer in Safe Mode with Networking option before running antivirus software on it. However, to ensure the optimal result, only genuine and strong antivirus should be used such as INTEGO Antivirus (recommended by us) or any other similar one with proven efficacy. You should also consider downloading RESTORO which you can use to repair damages left by the virus on the Windows OS files.

Ransomware Summary

REMOVE MALWARE & REPAIR VIRUS DAMAGE

Ransomware Distribution Techniques Commonly used by Cybercriminals

The most common way through which STOP/DJVU ransomware variants including MMUZ virus are spread is through malicious online torrents. In this method, cybercriminals will embed malware on certain pirated software copies including the so-called key generators and “cracks”, which would then be uploaded to online torrent platforms. When such software contents are downloaded by unsuspecting users, they usually result in severe malware attack. Reports by victims over the years have shown that certain pirated software contents are often used by cybercriminals to lure their victims through online torrents platforms, as listed below:

• KMSPico (illegal Windows activation tool).
• Fifa 20;
• Tenorshare 4ukey;
• AutoCad;
• Opera browser;
• Corel Draw;
• VMware Workstation;
• Cubase;
• Adobe Illustrator;
• League of Legends;
• Internet Download Manager;
• Adobe Photoshop.

For those that often go to online torrents platforms to download software content, this is a dangerous habit and you should desist from doing so. Cybercriminals are often hoping to prey on such people by encrypting their files once malware infiltrates their computer systems and use it for ransom purposes. Aside that, downloading pirated software copies is an act of infringement and is a punishable offense by law. Instead of engaging in such unwholesome practices, it is better to encourage legitimate and original software developers by getting the products through the legitimate channels endorsed by them.

Remember that whatever price they request for their software copies will always be insignificant relative to the outrageous ransom fees often demanded by cybercriminals from their victims. Likewise, you won’t be at risk of losing your precious data.

Another method of ransomware distribution exploited by cybercriminals is the use of malicious email attachments. In this method, cybercriminals usually create “real” looking messages that would be accompanied with documents crafted on platforms like XLS, DOCX or PDF. These particular ones are often used because they allow macro functions and JavaScript both of which can be used in downloading payload from one source to another where it would be triggered.

The most challenging problem is how to detect if an email is genuine or sent by cybercriminals. The reason is that cybercriminals now impersonate genuine people or brands just to deceive their target victims. Popular brands such as Amazon and eBay, as well as courier companies like DHL, UPS and FedEx are their favorites. They would also name the attachments compelling terms like Invoice, Tracking Details or Order Summary. Alternatively, they may even decide to make use of email spoofing techniques to ensure their actual address remains hidden. Whatever fraudulent method they may try to use, we advise everyone to remain vigilant at all times; if there is something unusual about an email, then it could be a red flag notifying you about a possible ransomware threat.

Lastly, those that have already become victims of STOP/DJVU ransomware should avoid some suspicious websites that make bogus claims about offering decryption solutions. So far, only repair tools provided by DiskTuna and Emsisoft have proven to be effective and you can follow this link to understand how to use them. However, most other repair tools are fake and ineffective, and only intended to be used for ulterior purposes.

More details to know about the infection

If you’re among those that are often curious to know the extent to which their computer systems were affected during MMUZ ransomware attack, then this section would come handy. First of all, what the malware does at the onset is to launch build.exe or build2.exe executables as well as winupdate.exe. After that, it will make a connection with https[:]//api.2ip.ua/geo.json and also save the result in geo.json file. Thereafter, the malware will begin information gathering of piece of information concerning your computer including its geolocation, zip code, time zone, latitude and longitude. Provided below is example of the geo.json file.

It will also create another file named information.txt where it would save compiled computer’s hardware details, installed software and active processes list.

At this stage, the virus will make a comparison between the country code is obtained from the computer and a list of countries they designated as encryption-exempted (Ukraine, Russian Federation, Syria, Armenia, Kyrgyzstan, Tajikistan, Kazachstan, Belarus, and Uzbekistan). If it ascertains that such computer is domiciled in any of these countries, it will immediately abort its mission but if otherwise, it will move to the next level by fetching an online encryption key, which would be merged with the victim’s ID and saved in the bowsakkdestx.txt file and also to the PersonalID.txt file. Shown below are examples of these files.

In situations whereby the virus couldn’t obtain an online encryption key that is usually kept in its server, it will automatically opt for the use of a hardcoded offline key. The major difference between both keys is that the online key is a more sophisticated and unique per victim while the offline version is uniform for all victims (it is preferable from the perspective of the victim since there is a high chance of .mmuz files decryption when it is used unlike online key). The presence of t1 characters appearing at the end of a victim’s ID is an indication that offline key was used. More information about this is provided below this article.

At this juncture, the ransomware would commence full data encryption by scanning folders and encrypting them with Salsa20, before ultimately locking the encryption key using RSA-2048 key. While the process is still ongoing, the files will be marked with additional extension.

Below is a screenshot of _readme.txt ransom note that is typically left in all the folders.

Lastly, the virus will blacklist certain domain names in the Windows HOSTS file and also map them on localhost IP, which effectively bars the victim from having access to them. Any attempt by the victim to browse them will yield DNS_PROBE_FINISHED_NXDOMAIN error message. The aim is to prevent the victim from getting any help online.

Remove MMUZ Ransomware Virus and Restore Your Files

If you have been infected with the described computer threat, now it is time to remove MMUZ ransomware virus. For this matter, we recommend booting your PC in Safe Mode with Networking. We have explained this in detail below. Moreover, do not recommend to use a robust antivirus solution, such as .

There are certain steps victims are recommended to take aside from MMUZ ransomware virus removal as listed below.

• Report to local law enforcement agency.
• Recover lost data using a backup drive.
• Learn possible ways STOP/DJVU files could be repaired.
• Change all passwords used on the infected computer.
• Download RESTORO to repair virus-infected operating system files.

OUR GEEKS RECOMMEND

Our team recommends a two-step rescue plan to remove ransomware and other remaining malware from your computer, plus repair caused virus damage to the system:

STEP 1. REMOVE AUTOMATICALLY WITH ROBUST ANTIVIRUS

REMOVE & PROTECT WITH INTEGO

Get INTEGO ANTIVIRUS for Windows to remove ransomware, Trojans, adware and other spyware and malware variants and protect your PC and network drives 24/7.. This VB100-certified security software uses state-of-art technology to provide protection against ransomware, Zero-Day attacks and advanced threats, Intego Web Shield blocks dangerous websites, phishing attacks, malicious downloads and installation of potentially unwanted programs.

Use INTEGO Antivirus to remove detected threats from your computer.

Read full review here.

STEP 2. REPAIR VIRUS DAMAGE TO YOUR COMPUTER

DOWNLOAD RESTORO

RESTORO provides a free scan that helps to identify hardware, security and stability issues and presents a comprehensive report which can help you to locate and fix detected issues manually. It is a great PC repair software to use after you remove malware with professional antivirus. The full version of software will fix detected issues and repair virus damage caused to your Windows OS files automatically.

RESTORO uses AVIRA scanning engine to detect existing spyware and malware. If any are found, the software will eliminate them.

Read full review here.

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Norbert Webb

Norbert Webb is the head of Geek’s Advice team. He is the chief editor of the website who controls the quality of content published. The man also loves reading cybersecurity news, testing new software and sharing his insights on them. Norbert says that following his passion for information technology was one of the best decisions he has ever made. “I don’t feel like working while I’m doing something I love.” However, the geek has other interests, such as snowboarding and traveling.