MegaCortex Ransomware

Also Known As: MegaCortex virus
Distribution: Low
Damage level: Severe

MegaCortex ransomware removal instructions

What is MegaCortex?

Ransomware is software that encrypts files stored on a computer and keeps them inaccessible unless a ransom is paid. MegaCortex is one of these programs and was discovered by Michael Gillespie. It also renames all encrypted files by adding the ".aes128ctr" extension. For example, "1.jpg" becomes "1.jpg.aes128ctr". Additionally, MegaCortex creates a ransom message within the "!!!_READ_ME_!!!.txt" file and places it in folders that contain encrypted files.

"!!!_READ_ME_!!!.txt" informs victims about how to decrypt their files. It states that the only way to do this is using their decryption tool. The cost is unknown, however, this information should be provided after contacting MegaCortex's developers via the or email address. Victims are urged not to restart or shut down computers, since this might cause permanent data loss. As 'proof' that they have a decryption tool, they offer free decryption of two files that should be send with the "fracxidg.tsv" file (according to them, this file is placed on the "C:" disk). Even if they decrypt a number of files free of charge, they should not be trusted. Ransomware developers often send no decryption tools even if their ransom demands are met. People who develop these programs use cryptography algorithms that ensure strong encryptions that are impossible to decrypt without using the correct tools held by specific cyber criminals. Typically, the only free way to re-access decrypted files is to restore them from a backup.

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

MegaCortex decrypt instructions

Some examples of other ransomware-type programs that are similar to MegaCortex are Prodecryptor, Todarius, and Sodinokibi. Most of these programs are designed to encrypt data and keep it locked unless a ransom is paid. Main differences are usually cost of a decryption (tool/key) and the type of cryptography algorithm (symmetric or asymmetric) used. The biggest problem is that most ransomware-type programs are impossible to 'crack' without using the correct tool. Only the developers have these tools. Decryption without their involvement is possible only if their programs are not finished and have bugs/flaws. Therefore, maintain regular backups and store them on remote servers or unplugged storage devices.

How did ransomware infect my computer?

Research shows that cyber criminals often proliferate MegaCortex using a Cobalt Strike trojan. Criminals use hijacked system admin accounts to run a PowerShell script, which is essentially a Base64-encoded Cobalt Strike script. This script opens a Meterpreter reverse shell, which allows cyber criminals to use the Windows PowerShell remotely. Criminals then use the reverse shell to download several files on all computers connected to the network. Therefore, MegaCortex is injected into multiple computers at once. Before running/executing the malware, criminals run a batch file which terminates more than one hundred system processes and disables start-on-startup. The MegaCortex excecutable is then opened. The list of terminated/disabled processes includes mostly those relating to system protection and anti-virus applications. As compared to other ransomware-type infections, this distribution method is ineffective, since most such infections are proliferated via spam email campaigns, Trojans, untrustworthy software download sources, unofficial (fake) software updaters and software 'cracking' tools. When criminals use spam campaigns, they send emails that include malicious attachments. The main goal of these emails is to trick people into opening the attachments, which are generally executables (.exe) files, PDF or Microsoft Office documents, archives such as ZIP, RAR, and JavaScript files. When opened, these files download and install ransomware or other high-risk computer infections. Trojans are malicious programs that cause chain infections, however, to cause any damage, they must first be installed. They then download and install other malicious programs. Peer-to-peer (P2P) networks, free file hosting and freeware download websites, various other third party software download sources (and unofficial pages) can be used by cyber criminals to proliferate viruses. They use these channels to present their malicious executables as legitimate. If downloaded and opened, however, they infect computers with malware. By using these channels, people risk computer infections. Fake software updaters infect systems by downloading malicious programs rather than the updates and fixes, or by exploiting bugs/flaws of installed and outdated software. Software 'cracking' tools are programs that activate licensed software free of charge, however, cyber criminals often use these tools to proliferate viruses. Rather than 'cracking' software, these programs download and install ransomware-type and other malicious programs.

Threat Summary:
Name MegaCortex virus
Threat Type Ransomware, Crypto Virus, Files locker.
Detection Names (winnit.exe) Avast (Win32:Malware-gen), BitDefender (Trojan.Ransom.CBH), ESET-NOD32 (a variant of Win32/Agent.AAPF), Kaspersky (UDS:DangerousObject.Multi.Generic), Full List Of Detections (VirusTotal)
Encrypted Files Extension .aes128ctr
Ransom Demanding Message !!!_READ_ME_!!!.txt text file.
Cyber Criminal Contact,
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)

To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Malwarebytes.
▼ Download Malwarebytes
To use full-featured product, you have to purchase a license for Malwarebytes. 14 days free trial available.

How to protect yourself from ransomware infections?

Analyze each email before opening attachments/links presented in them, especially if they are received from suspicious, unknown addresses and are irrelevant. Ignore these emails and leave attachments unopened. Download software from official websites and using direct download links. The aforementioned tools should not be trusted. Operating systems or installed programs should be updated using implemented functions or tools that are provided by the official software developers. The same applies to software activation. Third party 'cracking' tools are illegal and they often infect systems with malicious programs. Additionally, have a reputable anti-virus or anti-spyware suite installed and enabled. If your computer is already infected with MegaCortex, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.

Text presented in MegaCortex ransomware text file ("!!!_READ_ME_!!!.txt") :

Your companies cyber defense systems have been weighed, measured and have been found wanting.
The breach is a result of grave neglect of security protocols.
All of your computers have been corrupted with MegaCortex malware that has encrypted your files.

We ensure that the only way to retrieve your data swiftly and securely is with our software.
Restoration of your data requires a private key which only we possess.
Don't waste your time and money purchasing third party software, without the private key they are useless.

It is critical that you don't restart or shutdown your computer.
This may lead to irreversible damage to your data and you may not be able to turn your computer back on.

To confirm that our software works email to us 2 files from random computers and C:\fracxidg.tsv file('s)
and you will get them decrypted.
C:\fracxidg.tsv contain encrypted session keys we need in order to be able to decrypt your files.

The softwares price will include a guarantee that your company will never be inconvenienced by us.
You will also receive a consultation on how to improve your companies cyber security .
If you want to purchase our software to restore your data contact us at:

We can only show you the door. You're the one who has to walk through it.

Screenshot of files encrypted by MegaCortex (".aes128ctr" extension):

Files encrypted by MegaCortex

Update September 12, 2019 - Cyber criminals are promoting MegaCortex as Ransomware as a Service (RaaS), meaning that anyone can purchase the entire ransomware kit and start generating revenue by spreading malware and blackmailing victims.

Screenshot of the website used to promote MegaCortex as RaaS:

Website used to promote MegaCortex as RaaS

MegaCortex ransomware removal:

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Malwarebytes is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
▼ DOWNLOAD Malwarebytes By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. To use full-featured product, you have to purchase a license for Malwarebytes. 14 days free trial available.

Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the MegaCortex virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the MegaCortex ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining MegaCortex ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of MegaCortex are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by MegaCortex, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as MegaCortex ransomware.

Note that Windows 10 Fall Creators Update includes a "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default, this feature automatically protects files stored in the Documents, Pictures, Videos, Music, Favorites as well as Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here is more information on how to get this update and add an additional protection layer from ransomware infections.

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove MegaCortex ransomware:

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 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.

Our malware removal guides are free. However, if you want to support us you can send us a donation.

Removal Instructions in other languages
Malware activity

Global malware activity level today:

Medium threat activity

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

QR Code
MegaCortex virus QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of MegaCortex virus on your mobile device.
We Recommend:

Get rid of Windows malware infections today:

Download Malwarebytes

Platform: Windows

Editors' Rating for Malwarebytes:
Editors ratingOutstanding!

[Back to Top]

To use full-featured product, you have to purchase a license for Malwarebytes. 14 days free trial available.