Megac0rtx ransomware removal instructions

Also Known As: Megac0rtx virus
Damage level: Severe

What is Megac0rtx?

First discovered by MalwareHunterTeam, Megac0rtx is an updated variant of high-risk ransomware called MegaCortex. After successful infiltration, Megac0rtx compromises (encrypts) most stored data and appends each filename with the ".megac0rtx" extension (hence its name).

For example, "1.jpg" is renamed to "1.jpg.megac0rtx". Additionally, Megac0rtx deletes shadow volume copies and overwrites all deleted files, thereby making recovery impossible. Encrypted files also become unusable. After successful encryption, Megac0rtx stores the "!!!_READ-ME_!!!.txt" file on the desktop. The file contains a ransom-demand message.

As mentioned above, Megac0rtx uses a text file to deliver a ransom-demand message. It is stated that data is encrypted using AES-256 (symmetric) and RSA-4096 (asymmetric) cryptographies, and that a unique decryption tool is necessary to restore data. Unfortunately, this information is accurate.

AES and RSA are high-end cryptographies that generate unique decryption keys for each encryption. Therefore, at least two unique keys are necessary to restore data encrypted by Megac0rtx. Cyber criminals hide all keys on a remote server so that they are able to blackmail victims.

To receive their keys (or rather, decryption tools with keys embedded within), each victim must pay a ransom. The cost as compared to other ransomware-type infections is extremely high and fluctuates between 2 and 600 Bitcoins. At time of writing, the cost of one Bitcoin was just over $10,000. Therefore, the size of ransom could reach millions of dollars.

In the past, Megac0rtx was distributed manually and this is the reason why the cost of decryption is so high. Cyber criminals were compromising Windows domain controllers to gain access to a network of computers and infect the connected machines.

Note that criminals who use these distribution methods usually target companies who are much more likely to pay greater sums for sensitive and very important data that has been encrypted. It is unlikely that regular users would pay these sums to restore photos, audio/video files, or other similar data.

Although this method was used in the past, distributors have now changed their tactics and started to proliferate a basic Megac0rtx executable. Once opened, this immediately starts the encryption process. In this way, criminals avoid the challenge of manually injecting machines, and thus significantly increase the number of victims.

Nevertheless, this distribution method has a significant drawback: most victims are regular users and cannot afford to pay the ransom demands. Furthermore, note that ransomware developers in general ignore victims once payments are submitted. Thus, paying delivers no positive results and users are scammed.

Therefore, ignore all requests to contact these people or submit any payments. Unfortunately, there are no tools capable of cracking Megac0rtx encryption and restoring data free of charge. The only solution is to restore everything from a backup.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:

Megac0rtx decrypt instructions

The internet is full of ransomware-type infections that share similarities with Megac0rtx. Dodoc, Hades666, and V6cye - the list of examples goes on. Most ransomware infections encrypt data and make ransom demands.

Although the developers are different, all of these infections are virtually identical - the only major differences are cost of decryption and type of encryption algorithm used. In most cases, encryptions are performed using cryptographies such as AES, RSA, and others, that generate unique decryption keys.

Therefore, it is virtually impossible to restore data without involvement of developers (contacting these people is not recommended). The only possible scenarios are ransomware not being fully developed and/or having certain bugs/flaws (e.g., the key is stored locally, it is hard-coded or similar).

Ransomware presents a strong case for maintaining regular backups, however, note that locally stored backups are compromised together with regular data. Therefore, all backups should be stored on unplugged storage devices/servers. Additionally, have multiple backup copies stored in different locations, since devices/servers can be damaged.

How did ransomware infect my computer?

In the past, Megac0rtx was mostly distributed manually. Criminals compromised Windows domain controllers to hijack computer networks and install the Cobalt Strike trojan to open a reverse shell and download/execute Megac0rtx using PsExec. Since this method takes time, however, cyber criminals have started proliferating a simple versions of the malicious Megac0rtx executable.

These files are usually distributed using spam email campaigns (malicious attachments) and unofficial software download download sources. Spam campaigns are used to send hundreds of thousands of deceptive emails containing messages that encourage recipients to open attached links/files.

To give the impression of legitimacy and increase the chance of tricking recipients, criminals often present malicious attachments as 'important documents' such as invoices, bills, receipts, and similar. P2P (Peer-to-Peer) networks, freeware download/free file hosting sites, and other unofficial download sources are also used in a similar manner.

Criminals present malicious executables as reputable/genuine software, thereby tricking users into manually downloading and installing malware. Ransomware-type infections in general are also proliferated using trojans, fake software updaters, and 'cracks'.

Threat Summary:
Name Megac0rtx virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .megac0rtx
Ransom Demanding Message !!!_READ-ME_!!!.txt text file
Ransom Amount 2-600 Bitcoins
Cyber Criminal Contact mckinnisKamariyah91@mail.com, thomassenvallen1999@mail.com
Detection Names Avast (Win32:Malware-gen), BitDefender (Trojan.Ransom.MegaCortex.B), ESET-NOD32 (Win32/Filecoder.NWX), Kaspersky (Trojan-Ransom.Win32.MegaCortex.a), 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?

To prevent ransomware infections, pay close attention during the download/installation/update processes and when browsing the Internet in general. We strongly recommend that you download programs from official sources only, preferably using direct download links.

The same applies to software updates - installed programs/operating systems should be updated only using implemented functions or tools provided by the official developer. Third party software downloaders, installers and updaters are often used to proliferate rogue apps, and thus these tools should never be used.

Be aware that software piracy is a cyber crime, many cracks are fake, and the risk of infection is extremely high. Therefore, never attempt to crack installed applications. We strongly recommend that you handle all email attachments with care. Files/links that are irrelevant or do not concern you should never be opened.

The same applies to attachments received from suspicious/unrecognizable email addresses. Have a reputable anti-virus/anti-spyware suite installed and running - these tools reduce the risk of infection, since they detect and eliminate malware before the system is damaged.

The key to computer safety is caution. If your computer is already infected with Megac0rtx, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.

The appearance of Megac0rtx ransomware text file "!!!_READ-ME_!!!.txt" (GIF):

Megac0rtx pop-up gif

Text presented within this file:

If you are reading this text, it means, we've hacked your corporate network.
Now all your data is encrypted with very serious and powerful algorithms (AES256 and RSA-4,096).
These algorithms now in use in military intelligence, NSA and CIA .
No one can help you to restore your data without our special decipherer.
Don't even waste your time.

But there are good news for you.
We don't want to do any damage to your business.
We are working for profit.

The core of this criminal business is to give back your valuable data in the original form (for ransom of course).

In order to prove that we can restore all your data, we'll decrypt 3 of your files for free.
Please, attach 2-3 encrypted files to your first letter.
Each file must be less than 5 Mb, non-archived and your files should not contain valuable information
(databases, backups, large word files or excel sheets, etc.).
You will receive decrypted samples and our conditions how to get the decipherer.

For the fastest solution of the problem, please, write immediately in your first letter:
the name of your company,
the domain name of your corporate network and
the URL of your corporate website
It is important !

And please do not start your first letter to us with the words:
"It's a mistake !! Our company is just trimming and grooming little dogs. We don't have money at all."
"There is a big mistake on our site !
We are not leaders in our industry and all our competitors don't suck our huge dick.
We're just ? small company, and we are dying because of hard competition."
"We are not the Super Mega International Corporation ltd., we are just a nursery etc."

We see it 5 times a day. This shit doesn't work at all !!!
Don't waste our and your time.

Remember ! We don't work for food.
You have to pay for decryption in Bitcoins (BTC).
If you think you pay $500 and you'll get the decryptor, you are 50 million light years away from reality :)
The ransom begins from 2-3 BTC up to 600 BTC.
If you don't have money don't even write to us.
We don't do charity !

One more time :

1.(In first letter) write the name of your company, the domain name of your corporate network and the URL of your corporate website
2. Attach 2-3 encrypted files (we'll show you some magic)
3. Use Google in order to find out how to buy bitcoins fast

As soon as we get bitcoins you'll get all your decrypted data back.

Contact emails:



Man is the master of everything and decides everything.

Screenshot of files encrypted by Megac0rtx (".megac0rtx" extension):

Files encrypted by Megac0rtx

Megac0rtx 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.

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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.

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Malware activity

Global malware activity level today:

Medium threat activity

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

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