Lorenz (.Lorenz.sz40) ransomware virus - removal and decryption options

Also Known As: Lorenz virus
Damage level: Severe

What is Lorenz ransomware?

Lorenz is a new variant of the Sz40 ransomware. It is designed to encrypt data and demand ransoms for the decryption. In other words, Lorenz renders affected files inaccessible and asks victims to pay - to recover access to their data.

During the encryption process, files are appended with the ".Lorenz.sz40" extension. For example, a file initially titled "1.jpg" would appear as "1.jpg.Lorenz.sz40", "2.jpg" as "2.jpg.Lorenz.sz40", and so forth.

After the encryption process is complete, a ransom note with the filename "HELP_SECURITY_EVENT.html" is created.

At the time of research, Lorenz ransomware had a bug (flaw), which would corrupt certain files. This corruption occurred due to a portion of the encrypted file being deleted. Hence, full recovery of these files is not possible even with the cyber criminals' involvement.

However, there is a free decryption tool capable of restoring Lorenz-encrypted (but non-corrupted) files. This decryptor supports Microsoft Office and PDF documents, as well as some image and video format files. The decryption software was developed by Tesorion; it can be downloaded via the NoMoreRansom initiative - free of charge.

Screenshot of files encrypted by Lorenz ransomware:

Files encrypted by Lorenz ransomware (.Lorenz.sz40 extension)

Lorenz ransom note overview

The ransom-demanding message ("HELP_SECURITY_EVENT.html") informs victims that their files were exfiltrated (downloaded) and encrypted. According to the note, the sole method of recovering the locked data is by meeting the cyber criminals' demands.

To get further instructions, victims are instructed to visit Lorenz's webpage, which is accessible only via the Tor browser. On the site, they will be able to test decryption by uploading some of the encrypted files.

Should victims fail to meet the criminals' demands within the unspecified timeframe, the content extracted from their devices - will be publicized on the Web. The message contains the address of the data-leaking website used by Lorenz.

The note is concluded with warnings. Victims are alerted that modifying the encrypted files, attempting to decrypt them with third-party tools, and/or using anti-virus software - can result in permanent data loss.

Lorenz ransomware in detail

While there is a decryption tool that can restore files affected by Lorenz, that is not the case with most ransomware infections. Typically, without the cyber criminals' interference - decryption is impossible. It might be when a ransomware-type program has severe flaws and/or is still in development.

Regardless, victims should never meet the ransom demands since they often do not receive the promised decryption tools/software despite paying. Therefore, victims' data remains encrypted (essentially useless) and they experience a financial loss.

To prevent ransomware from further encryptions - it must be removed from the operating system. However, removal will not restore already compromised files.

Hence, if there are no third-party decryptors available, the sole solution is recovering the data from a backup. Provided if a backup was created before the infection and stored in a different location.

Similarities with other infections

F1HivePoliex, and Leex are a few examples of malicious programs within the ransomware category. Malware of this type operates by encrypting data and/or locking the device's screen - in order to demand payment for the decryption/ access recovery.

There are two significant differences in-between ransomware - the cryptographic algorithms it uses (symmetric or asymmetric) and the ransom size.

It is highly recommended to store backups in remote servers and/or unplugged storage devices - to avoid permanent data loss. Additionally, it is best to store backup copies in multiple separate locations.

How did ransomware infect my computer?

Ransomware and other malware are distributed using a wide variety of methods and tactics. Malicious software is usually disguised as or bundled (packed together) with ordinary programs/media.

Untrustworthy download channels, e.g., unofficial and free file-hosting (freeware) websites, P2P sharing networks (Torrent clients, eMule, Gnutella, etc.), and other third-party sources - are commonly used to spread malicious programs.

Illegal activation ("cracking") tools and fake updates are prime examples of malware-proliferating content. "Cracks" can infect systems instead of activating licensed products. Fraudulent updaters cause infections by exploiting weaknesses of outdated software and/or by installing malware rather than the promised updates.

Malware is also distributed via spam campaigns - mass-scale operations during which thousands of deceptive emails are sent. These letters are presented as "official", "urgent", "important", "priority", and similar.

Scam emails can contain download links of malicious content and/or have infectious files attached to them. Virulent files can be in various formats, e.g., archives (ZIP, RAR, etc.), executables (.exe, .run, etc.), Microsoft Office and PDF documents, JavaScript, and so on. When the files are opened - the infection chain is initiated.

Threat Summary:
Name Lorenz virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .Lorenz.sz40
Ransom Demanding Message HELP_SECURITY_EVENT.html
Free Decryptor Available? Yes; Tesorion developed a free decryption tool for Lorenz ransomware
Cyber Criminal Contact Website on Tor network
Detection Names Avast (Win32:Dh-A [Heur]), BitDefender (Trojan.GenericKD.46337031), ESET-NOD32 (Win32/Filecoder.OHE), Kaspersky (HEUR:Trojan-Ransom.Win32.Gen.gen), Microsoft (Trojan:Win32/CryptInject!MSR), Full List Of Detections (VirusTotal)
Symptoms Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password-stealing trojans and malware infections can be installed together with a ransomware infection.
Malware Removal (Windows)

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How to protect yourself from ransomware infections?

It is advised to perform downloads only from official and verified sources. Furthermore, all software products must be activated and updated with tools/functions provided by legitimate developers.

To avoid infecting the system via spam mail, it is recommended to exercise caution with incoming emails. Suspicious and irrelevant email letters must not be opened, especially any links or attachments found in them.

It is paramount to have a dependable anti-virus/anti-spyware suite installed and kept updated. This software has to be used to run regular system scans and to remove detected/potential threats and issues. If your computer is already infected with Lorenz, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.

Screenshot of Lorenz ransomware's ransom note ("HELP_SECURITY_EVENT.html"):

Lorenz ransomware ransom-demanding message (HELP_SECURITY_EVENT.html)

Text presented in Lorenz's message:

---===Lorenz. Welcome. Again. ===---

[+] Whats Happen? [+]


Your files are downloaded, encrypted, and currently unavailable. You can check it.
By the way, everything is possible to recover (restore), but you need to follow our instructions. Otherwise, you can't return your data (NEVER).


[+] What guarantees? [+]


It's just a business. We absolutely do not care about you and your deals, except getting benefits. If we do not do our work and liabilities - nobody will not cooperate with us. Its not in our interests.To check the ability of returning files, You should go to our website. There you can decrypt some file's for free. That is our guarantee. If you will not cooperate with our service - for us, it's does not matter. After deadline we'll publish all the contents of your company to site and we'll send all information to your client's and mass media. You will lose your time, data and reputation.Unfortunately many people if they see their personal info into web, will go to court. And for you it will be cost much expensive.


[+] How to get access on website? [+]


Using a TOR browser!


a) Download and install TOR browser from this site: hxxps://torproject.org/
b) Open our website: hxxp://6ch5sszxxlypo6tybukxmqeavslnfhcoe77io3kdykhowj4kqufga7yd.onion
c) Check our website with leaks: hxxp://lorenzmlwpzgxq736jzseuterytjueszsvznuibanxomlpkyxk6ksoyd.onion


When you open our website, put the following data in the input form:
Company Key:




!!! DANGER !!!
DONT try to change files by yourself, DONT use any third party software for restoring your data or antivirus solutions - its may entail damage of the private key and, as result, The Loss all data.!!!
ONE MORE TIME: Its in your interests to get your files back. From our side, we (the best specialists) make everything for restoring, but please should not interfere.!!!

The appearance of Lorenz's ransom note (GIF):

Lorenz ransomware note appearance GIF (HELP_SECURITY_EVENT.html)

Screenshot of Lorenz's desktop wallpaper:

Lorenz ransomware wallpaper

Screenshot of Lorenz's data-leaking website:

Lorenz ransomware data-leaking site

Screenshot of the decryptor developed by Tesorion (GIF):

Decryption tool for Lorenz ransomware (GIF)

Update 11 January 2022: It is known that cybercriminals behind Lorenz ransomware had used a long-lived malicious script that compromises the web server to attack users. They exploited a critical vulnerability (CVE-2022-29499) in the victim's Mitel telephony infrastructure.

They were able to exploit the aforementioned vulnerability and plant a backdoor before the release of an update that fixed the issue. It is possible that cybercriminals are still returning to old backdoors and using them to carry out Lorenz ransomware attacks.

Lorenz ransomware removal:

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Video suggesting what steps should be taken in case of a ransomware infection:

Quick menu:

Reporting ransomware to authorities:

If you are a victim of a ransomware attack we recommend reporting this incident to authorities. By providing information to law enforcement agencies you will help track cybercrime and potentially assist in the prosecution of the attackers. Here's a list of authorities where you should report a ransomware attack. For the complete list of local cybersecurity centers and information on why you should report ransomware attacks, read this article.

List of local authorities where ransomware attacks should be reported (choose one depending on your residence address):

Isolating the infected device:

Some ransomware-type infections are designed to encrypt files within external storage devices, infect them, and even spread throughout the entire local network. For this reason, it is very important to isolate the infected device (computer) as soon as possible.

Step 1: Disconnect from the internet.

The easiest way to disconnect a computer from the internet is to unplug the Ethernet cable from the motherboard, however, some devices are connected via a wireless network and for some users (especially those who are not particularly tech-savvy), disconnecting cables may seem troublesome. Therefore, you can also disconnect the system manually via Control Panel:

Navigate to the "Control Panel", click the search bar in the upper-right corner of the screen, enter "Network and Sharing Center" and select search result: Disconnecting computer from the Internet (step 1)

Click the "Change adapter settings" option in the upper-left corner of the window: Disconnecting computer from the Internet (step 2)

Right-click on each connection point and select "Disable". Once disabled, the system will no longer be connected to the internet. To re-enable the connection points, simply right-click again and select "Enable". Disconnecting computer from the Internet (step 3)

Step 2: Unplug all storage devices.

As mentioned above, ransomware might encrypt data and infiltrate all storage devices that are connected to the computer. For this reason, all external storage devices (flash drives, portable hard drives, etc.) should be disconnected immediately, however, we strongly advise you to eject each device before disconnecting to prevent data corruption:

Navigate to "My Computer", right-click on each connected device, and select "Eject": Ejecting external storage devices

Step 3: Log-out of cloud storage accounts.

Some ransomware-type might be able to hijack software that handles data stored within "the Cloud". Therefore, the data could be corrupted/encrypted. For this reason, you should log-out of all cloud storage accounts within browsers and other related software. You should also consider temporarily uninstalling the cloud-management software until the infection is completely removed.

Identify the ransomware infection:

To properly handle an infection, one must first identify it. Some ransomware infections use ransom-demand messages as an introduction (see the WALDO ransomware text file below).

Identify ransomware-type infection (step 1)

This, however, is rare. In most cases, ransomware infections deliver more direct messages simply stating that data is encrypted and that victims must pay some sort of ransom. Note that ransomware-type infections typically generate messages with different file names (for example, "_readme.txt", "READ-ME.txt", "DECRYPTION_INSTRUCTIONS.txt", "DECRYPT_FILES.html", etc.). Therefore, using the name of a ransom message may seem like a good way to identify the infection. The problem is that most of these names are generic and some infections use the same names, even though the delivered messages are different and the infections themselves are unrelated. Therefore, using the message filename alone can be ineffective and even lead to permanent data loss (for example, by attempting to decrypt data using tools designed for different ransomware infections, users are likely to end up permanently damaging files and decryption will no longer be possible even with the correct tool).

Another way to identify a ransomware infection is to check the file extension, which is appended to each encrypted file. Ransomware infections are often named by the extensions they append (see files encrypted by Qewe ransomware below).

Identify ransomware-type infection (step 2)

This method is only effective, however, when the appended extension is unique - many ransomware infections append a generic extension (for example, ".encrypted", ".enc", ".crypted", ".locked", etc.). In these cases, identifying ransomware by its appended extension becomes impossible.

One of the easiest and quickest ways to identify a ransomware infection is to use the ID Ransomware website. This service supports most existing ransomware infections. Victims simply upload a ransom message and/or one encrypted file (we advise you to upload both if possible).

Identify ransomware-type infection (step 3)

The ransomware will be identified within seconds and you will be provided with various details, such as the name of the malware family to which the infection belongs, whether it is decryptable, and so on.

Example 1 (Qewe [Stop/Djvu] ransomware):

Identify ransomware-type infection (step 4)

Example 2 (.iso [Phobos] ransomware):

Identify ransomware-type infection (step 5)

If your data happens to be encrypted by ransomware that is not supported by ID Ransomware, you can always try searching the internet by using certain keywords (for example, a ransom message title, file extension, provided contact emails, crypto wallet addresses, etc.).

Search for ransomware decryption tools:

Encryption algorithms used by most ransomware-type infections are extremely sophisticated and, if the encryption is performed properly, only the developer is capable of restoring data. This is because decryption requires a specific key, which is generated during the encryption. Restoring data without the key is impossible. In most cases, cybercriminals store keys on a remote server, rather than using the infected machine as a host. Dharma (CrySis), Phobos, and other families of high-end ransomware infections are virtually flawless, and thus restoring data encrypted without the developers' involvement is simply impossible. Despite this, there are dozens of ransomware-type infections that are poorly developed and contain a number of flaws (for example, the use of identical encryption/decryption keys for each victim, keys stored locally, etc.). Therefore, always check for available decryption tools for any ransomware that infiltrates your computer.

Finding the correct decryption tool on the internet can be very frustrating. For this reason, we recommend that you use the No More Ransom Project and this is where identifying the ransomware infection is useful. The No More Ransom Project website contains a "Decryption Tools" section with a search bar. Enter the name of the identified ransomware, and all available decryptors (if there are any) will be listed.

Searching for ransomware decryption tools in nomoreransom.org website

Restore files with data recovery tools:

Depending on the situation (quality of ransomware infection, type of encryption algorithm used, etc.), restoring data with certain third-party tools might be possible. Therefore, we advise you to use the Recuva tool developed by CCleaner. This tool supports over a thousand data types (graphics, video, audio, documents, etc.) and it is very intuitive (little knowledge is necessary to recover data). In addition, the recovery feature is completely free.

Step 1: Perform a scan.

Run the Recuva application and follow the wizard. You will be prompted with several windows allowing you to choose what file types to look for, which locations should be scanned, etc. All you need to do is select the options you're looking for and start the scan. We advise you to enable the "Deep Scan" before starting, otherwise, the application's scanning capabilities will be restricted.

Recuva data recovery tool wizard

Wait for Recuva to complete the scan. The scanning duration depends on the volume of files (both in quantity and size) that you are scanning (for example, several hundred gigabytes could take over an hour to scan). Therefore, be patient during the scanning process. We also advise against modifying or deleting existing files, since this might interfere with the scan. If you add additional data (for example, downloading files/content) while scanning, this will prolong the process:

Recuva data recovery tool scan time

Step 2: Recover data.

Once the process is complete, select the folders/files you wish to restore and simply click "Recover". Note that some free space on your storage drive is necessary to restore data:

Recuva data recovery tool recovering data

Create data backups:

Proper file management and creating backups is essential for data security. Therefore, always be very careful and think ahead.

Partition management: We recommend that you store your data in multiple partitions and avoid storing important files within the partition that contains the entire operating system. If you fall into a situation whereby you cannot boot the system and are forced to format the disk on which the operating system is installed (in most cases, this is where malware infections hide), you will lose all data stored within that drive. This is the advantage of having multiple partitions: if you have the entire storage device assigned to a single partition, you will be forced to delete everything, however, creating multiple partitions and allocating the data properly allows you to prevent such problems. You can easily format a single partition without affecting the others - therefore, one will be cleaned and the others will remain untouched, and your data will be saved. Managing partitions is quite simple and you can find all the necessary information on Microsoft's documentation web page.

Data backups: One of the most reliable backup methods is to use an external storage device and keep it unplugged. Copy your data to an external hard drive, flash (thumb) drive, SSD, HDD, or any other storage device, unplug it and store it in a dry place away from the sun and extreme temperatures. This method is, however, quite inefficient, since data backups and updates need to be made regularly. You can also use a cloud service or remote server. Here, an internet connection is required and there is always the chance of a security breach, although it's a really rare occasion.

We recommend using Microsoft OneDrive for backing up your files. OneDrive lets you store your personal files and data in the cloud, sync files across computers and mobile devices, allowing you to access and edit your files from all of your Windows devices. OneDrive lets you save, share and preview files, access download history, move, delete, and rename files, as well as create new folders, and much more.

You can back up your most important folders and files on your PC (your Desktop, Documents, and Pictures folders). Some of OneDrive’s more notable features include file versioning, which keeps older versions of files for up to 30 days. OneDrive features a recycling bin in which all of your deleted files are stored for a limited time. Deleted files are not counted as part of the user’s allocation.

The service is built using HTML5 technologies and allows you to upload files up to 300 MB via drag and drop into the web browser or up to 10 GB via the OneDrive desktop application. With OneDrive, you can download entire folders as a single ZIP file with up to 10,000 files, although it can’t exceed 15 GB per single download.

OneDrive comes with 5 GB of free storage out of the box, with an additional 100 GB, 1 TB, and 6 TB storage options available for a subscription-based fee. You can get one of these storage plans by either purchasing additional storage separately or with Office 365 subscription.

Creating a data backup:

The backup process is the same for all file types and folders. Here’s how you can back up your files using Microsoft OneDrive

Step 1: Choose the files/folders you want to backup.

Click the OneDrive icon in the taskbar

Click the OneDrive cloud icon to open the OneDrive menu. While in this menu, you can customize your file backup settings.

Select Help & Settings and click Settings

Click Help & Settings and then select Settings from the drop-down menu.

Select the Backup tab and click Manage backup

Go to the Backup tab and click Manage backup.

Select folders to backup and click Start backup

In this menu, you can choose to backup the Desktop and all of the files on it, and Documents and Pictures folders, again, with all of the files in them. Click Start backup.

Now, when you add a file or folder in the Desktop and Documents and Pictures folders, they will be automatically backed up on OneDrive.

To add folders and files, not in the locations shown above, you have to add them manually.

Select a file manually and copy it

Open File Explorer and navigate to the location of the folder/file you want to backup. Select the item, right-click it, and click Copy.

Paste the copied file in the OneDrive folder to create a backup

Then, navigate to OneDrive, right-click anywhere in the window and click Paste. Alternatively, you can just drag and drop a file into OneDrive. OneDrive will automatically create a backup of the folder/file.

File statuses in OneDrive folder

All of the files added to the OneDrive folder are backed up in the cloud automatically. The green circle with the checkmark in it indicates that the file is available both locally and on OneDrive and that the file version is the same on both. The blue cloud icon indicates that the file has not been synced and is available only on OneDrive. The sync icon indicates that the file is currently syncing.

Click Help & Settings and click View Online

To access files only located on OneDrive online, go to the Help & Settings drop-down menu and select View online.

Click the Settings cog and click Options

Step 2: Restore corrupted files.

OneDrive makes sure that the files stay in sync, so the version of the file on the computer is the same version on the cloud. However, if ransomware has encrypted your files, you can take advantage of OneDrive’s Version history feature that will allow you to restore the file versions prior to encryption.

Microsoft 365 has a ransomware detection feature that notifies you when your OneDrive files have been attacked and guide you through the process of restoring your files. It must be noted, however, that if you don’t have a paid Microsoft 365 subscription, you only get one detection and file recovery for free.

If your OneDrive files get deleted, corrupted, or infected by malware, you can restore your entire OneDrive to a previous state. Here’s how you can restore your entire OneDrive:


1. If you're signed in with a personal account, click the Settings cog at the top of the page. Then, click Options and select Restore your OneDrive.

If you're signed in with a work or school account,  click the Settings cog at the top of the page. Then, click Restore your OneDrive.

2. On the Restore your OneDrive page, select a date from the drop-down list. Note that if you're restoring your files after automatic ransomware detection, a restore date will be selected for you.

3. After configuring all of the file restoration options, click Restore to undo all the activities you selected.

The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups.

Frequently Asked Questions (FAQ)

How was my computer hacked and how did hackers encrypt my files?

Ransomware executables are commonly executed (opened) by the victims themselves, as they are typically disguises as or bundled with ordinary content. Malware (ransomware included) is primarily spread using phishing and social engineering techniques. The most common distribution methods include: drive-by downloads, spam mail, online scams, freeware and third-party download webpages, Peer-to-Peer sharing networks, illegal software activation tools ("cracks"), fake updates, and so on.

How to open ".Lorenz.sz40" files?

Ransomware-encrypted files can only be opened/used after they are decrypted.

Where should I look for free decryption tools for Lorenz ransomware?

Tesorion has released a free decryption tool for Lorenz (more information above).

Will Combo Cleaner help me remove Lorenz ransomware?

Yes, Combo Cleaner can scan devices and eliminate active ransomware infections. It is noteworthy that while using an anti-virus is the first step in ransomware recovery - security software is incapable of restoring encrypted files.

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About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

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