Home > Ransomware > Top 3 Ransomware Families of 2015. CryptoWall

Top 3 Ransomware Families of 2015. CryptoWall

In a series of three articles, we will analyze the features of the ransomware families of Cryptowall, CryptoLocker and TorrentLocker. The three families have proven to be the most notorious ones, generating large amounts of money and affecting thousands of files. In the first part, we will also focus on the common features that the three threats share. Let’s begin with CryptoWall…

Top3-Ransomware-Families-2015-CryptowallRansomware has been around for many years, although the file-encrypting ransomware is quite new to the malware world. The file encryption threat was first observed in 2013, when the first variant of the CryptoLocker infections took place. Those attacks were traced back to the creator of the infamous Zeus banking malware – Evgeniy Mikhailovich Bogachev also known by his nickname Slavik.

The vicious 2013 CryptoLocker was followed by many other attacks. Some of them were part of the CryptoLocker family, while others were not known and emerged from completely new families. Some of these ransomware threats were quickly put to sleep, and others stayed active for a longer period of time.

On the verge of 2016, malware researchers at Fox IT have successfully identified three big Ransomware families, whose members have generated huge income in 2015:

Similarities in the Threat Behavior of Cryptowall, CryptoLocker, TorrentLocker

The three ransomware have many variants, most of them still being active in the wild. The attacks have happened in similar patterns and have affected countries from all over the world – mainly through exploit kits and fake emails posing as official organizations.

While the multiple ransomware variants have displayed different behavior patterns, the file types they are after and their cryptographic functionalities are often quite alike. We are going to analyze Cryptowall, and then CTB-Locker and TorrentLocker, according to the two factors listed below:

1.File-System Behavior

Most ransomware types are designed to place their payment instruction files in the directory of the files that are about to be encrypted. These files are typically in the form of a text, image and/or URL. Changing the background wallpaper of the infected computer to these instructions is also a common feature. In addition, a popup window may also be included to make sure the user knows his files are encrypted and he can only restore them by paying a ransom .In attacks on businesses, some ransomware types can encrypt files on drives that are network mapped on the victim’s computer.

2.Network Behavior

Most ransomware families communicate with a command & control server. The communication can happen either via Tor or, in other cases, through a compromised WordPress website.

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CryptoWall Threat Behavior Drilldown

Extensive research on CryptoWall indicates that it has been around since November 2013 or possibly even earlier. However, the malicious encrypting threat was active and in a prolonged development process before it became known as CryptoWall. The ransomware piece was initially known as CryptoDefense. Back then, the threat would generate the encryption keys on the local machine, something its authors fixed in the later versions.

CryptoDefense has been through many changes to evolve into the most malevolent ransomware to this date – CryptoWall 3.0.

CryptoWall’s earlier versions were set to communicate via proxy servers which would forward traffic towards the command & control server located in Tor. In newer versions of CryptoWall, the communication with the control server happened directly over the Tor network. Even though this may have been only done in a test version of the threat, it was later used by criminals as their primary method of remote communication.

In later versions, an I2P network was used. After going through many tests, the ransomware authors settled for a communication setup with two layers of proxies. These proxies are located on hacked websites. Even though these servers are quickly taken offline, they are still effective for the criminals. You may wonder why. CryptoWall only needs one connection to be able to obtain an encryption key. To say it in other words, CryptoWall doesn’t need a consistent command & control server. This feature is the primary difference between CryptoWall and other pieces of malicious software.

Read More about CryptoWall 3.0 mechanisms and how to protect your system.

CryptoWall’s Secret to Success

Whoever invented CryptoWall also created an affiliate program, thus making the ransom software accessible to other individuals. Such affiliate programs sensibly boost the income generated by CryptoWall, and are also used by other forms of ransomware.

CryptoWall Network Behavior

Once on the targeted system, CryptoWall starts looking for a functioning proxy server. When such is located, the malware will start sending its command & control server the following bits of information:

  • A unique campaign identifier to determine the source of the infection.
  • Its IP address to locate the infection geographically.
  • Its unique identifier so that the particular infection is isolated from other infections.

After these are checked, the server will respond with:

  • The location of the ransom payment page, made available for the victims to buy the decryption software.
  • The victim’s country.
  • The RSA-2048 public key applied for file encryption.

Once the needed information is obtained by the hackers, CryptoWall will report the exact amount of the encrypted files back to its command and control server. The server will then respond with a ransom image displayed to the user:

CryptoWall File-System Behavior

Apart from encrypting the files specified in its target file-types list, CryptoWall will also make sure to:

  • Drop the lock screen image.
  • Drop a TXT file containing the same instructions as on the ransom image.

CryptoWall will also disable the volume shadow copies, also known as Volume Snapshot Service, Volume Shadow Copy Service or simply VSS. The Windows Error Recovery boot screen will also be disabled. On top of it all, CryptoWall will impair the Windows updates and it will disable the security services on the victim’s machine.

This article is based on research by the Dutch company Fox IT.

To be continued…

Stay tuned! Part II is coming soon! Until then, you’re welcome to join our security forums and tell us about your experience with ransomware!

Update: Part II. CTB-Locker.

Spy Hunter scanner will only detect the threat. If you want the threat to be automatically removed, you need to purchase the full version of the anti-malware tool.Find Out More About SpyHunter Anti-Malware Tool / How to Uninstall SpyHunter

Milena Dimitrova

An inspired writer and content manager who has been with SensorsTechForum since the project started. A professional with 10+ years of experience in creating engaging content. Focused on user privacy and malware development, she strongly believes in a world where cybersecurity plays a central role. If common sense makes no sense, she will be there to take notes. Those notes may later turn into articles! Follow Milena @Milenyim

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How to Remove from Windows.

Step 1: Boot Your PC In Safe Mode to isolate and remove


Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your PC with SpyHunter

Keep in mind, that SpyHunter’s scanner is only for malware detection. If SpyHunter detects malware on your PC, you will need to purchase SpyHunter's malware removal tool to remove the malware threats. Read our SpyHunter 5 review. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria

1. Hold Windows key() + R

2. The "Run" Window will appear. In it, type "msconfig" and click OK.

3. Go to the "Boot" tab. There select "Safe Boot" and then click "Apply" and "OK".
Tip: Make sure to reverse those changes by unticking Safe Boot after that, because your system will always boot in Safe Boot from now on.

4. When prompted, click on "Restart" to go into Safe Mode.

5. You can recognise Safe Mode by the words written on the corners of your screen.

Step 2: Uninstall and related software from Windows

Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:

1. Hold the Windows Logo Button and "R" on your keyboard. A Pop-up window will appear.

2. In the field type in "appwiz.cpl" and press ENTER.

3. This will open a window with all the programs installed on the PC. Select the program that you want to remove, and press "Uninstall"
Follow the instructions above and you will successfully uninstall most programs.

Step 3: Clean any registries, created by on your computer.

The usually targeted registries of Windows machines are the following:

  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

You can access them by opening the Windows registry editor and deleting any values, created by there. This can happen by following the steps underneath:

1. Open the Run Window again, type "regedit" and click OK.

2. When you open it, you can freely navigate to the Run and RunOnce keys, whose locations are shown above.

3. You can remove the value of the virus by right-clicking on it and removing it.
Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.

Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.

Step 4: Scan for with SpyHunter Anti-Malware Tool

1. Click on the "Download" button to proceed to SpyHunter's download page.

It is recommended to run a scan before purchasing the full version of the software to make sure that the current version of the malware can be detected by SpyHunter. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria.

2. After you have installed SpyHunter, wait for it to update automatically.


3. After the update process has finished, click on the 'Malware/PC Scan' tab. A new window will appear. Click on 'Start Scan'.


4. After SpyHunter has finished scanning your PC for any files of the associated threat and found them, you can try to get them removed automatically and permanently by clicking on the 'Next' button.


If any threats have been removed, it is highly recommended to restart your PC.

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Get rid of from Mac OS X.

Step 1: Uninstall and remove related files and objects

Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your Mac with SpyHunter for Mac
Keep in mind, that SpyHunter for Mac needs to purchased to remove the malware threats. Click on the corresponding links to check SpyHunter’s EULA and Privacy Policy

1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:

2. Find Activity Monitor and double-click it:

3. In the Activity Monitor look for any suspicious processes, belonging or related to :

Tip: To quit a process completely, choose the “Force Quit” option.

4. Click on the "Go" button again, but this time select Applications. Another way is with the ⇧+⌘+A buttons.

5. In the Applications menu, look for any suspicious app or an app with a name, similar or identical to . If you find it, right-click on the app and select “Move to Trash”.

6: Select Accounts, after which click on the Login Items preference. Your Mac will then show you a list of items that start automatically when you log in. Look for any suspicious apps identical or similar to . Check the app you want to stop from running automatically and then select on the Minus (“-“) icon to hide it.

7: Remove any left-over files that might be related to this threat manually by following the sub-steps below:

  • Go to Finder.
  • In the search bar type the name of the app that you want to remove.
  • Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
  • If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.

In case you cannot remove via Step 1 above:

In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:

Disclaimer! If you are about to tamper with Library files on Mac, be sure to know the name of the virus file, because if you delete the wrong file, it may cause irreversible damage to your MacOS. Continue on your own responsibility!

1: Click on "Go" and Then "Go to Folder" as shown underneath:

2: Type in "/Library/LauchAgents/" and click Ok:

3: Delete all of the virus files that have similar or the same name as . If you believe there is no such file, do not delete anything.

You can repeat the same procedure with the following other Library directories:

→ ~/Library/LaunchAgents

Tip: ~ is there on purpose, because it leads to more LaunchAgents.

Step 2: Scan for and remove files from your Mac

When you are facing problems on your Mac as a result of unwanted scripts and programs such as , the recommended way of eliminating the threat is by using an anti-malware program. SpyHunter for Mac offers advanced security features along with other modules that will improve your Mac’s security and protect it in the future.

Click the button below below to download SpyHunter for Mac and scan for :


SpyHunter for Mac

Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer Stop Push Pop-ups

Remove from Google Chrome.

Step 1: Start Google Chrome and open the drop menu

Step 2: Move the cursor over "Tools" and then from the extended menu choose "Extensions"

Step 3: From the opened "Extensions" menu locate the unwanted extension and click on its "Remove" button.

Step 4: After the extension is removed, restart Google Chrome by closing it from the red "X" button at the top right corner and start it again.

Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer Stop Push Pop-ups

Erase from Mozilla Firefox.

Step 1: Start Mozilla Firefox. Open the menu window

Step 2: Select the "Add-ons" icon from the menu.

Step 3: Select the unwanted extension and click "Remove"

Step 4: After the extension is removed, restart Mozilla Firefox by closing it from the red "X" button at the top right corner and start it again.

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Uninstall from Microsoft Edge.

Step 1: Start Edge browser.

Step 2: Open the drop menu by clicking on the icon at the top right corner.

Step 3: From the drop menu select "Extensions".

Step 4: Choose the suspected malicious extension you want to remove and then click on the gear icon.

Step 5: Remove the malicious extension by scrolling down and then clicking on Uninstall.

Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer Stop Push Pop-ups

Remove from Safari.

Step 1: Start the Safari app.

Step 2: After hovering your mouse cursor to the top of the screen, click on the Safari text to open its drop down menu.

Step 3: From the menu, click on "Preferences".

stf-safari preferences

Step 4: After that, select the 'Extensions' Tab.


Step 5: Click once on the extension you want to remove.

Step 6: Click 'Uninstall'.

stf-safari uninstall

A pop-up window will appear asking for confirmation to uninstall the extension. Select 'Uninstall' again, and the will be removed.

How to Reset Safari
IMPORTANT: Before resetting Safari make sure you back up all your saved passwords within the browser in case you forget them.

Start Safari and then click on the gear leaver icon.

Click the Reset Safari button and you will reset the browser.

Windows Mac OS X Google Chrome Mozilla Firefox Microsoft Edge Safari Internet Explorer Stop Push Pop-ups

Eliminate from Internet Explorer.

Step 1: Start Internet Explorer.

Step 2: Click on the gear icon labeled 'Tools' to open the drop menu and select 'Manage Add-ons'

Step 3: In the 'Manage Add-ons' window.

Step 4: Select the extension you want to remove and then click 'Disable'. A pop-up window will appear to inform you that you are about to disable the selected extension, and some more add-ons might be disabled as well. Leave all the boxes checked, and click 'Disable'.

Step 5: After the unwanted extension has been removed, restart Internet Explorer by closing it from the red 'X' button located at the top right corner and start it again.

Remove Push Notifications caused by from Your Browsers.

Turn Off Push Notifications from Google Chrome

To disable any Push Notices from Google Chrome browser, please follow the steps below:

Step 1: Go to Settings in Chrome.


Step 2: In Settings, select “Advanced Settings”:

advanced settings

Step 3: Click “Content Settings”:

Content Settings

Step 4: Open “Notifications”:


Step 5: Click the three dots and choose Block, Edit or Remove options:

Block, Edit or Remove

Remove Push Notifications on Firefox

Step 1: Go to Firefox Options.


Step 2: Go to “Settings”, type “notifications” in the search bar and click "Settings":


Step 3: Click “Remove” on any site you wish notifications gone and click “Save Changes”

remove push notifications firefox

Stop Push Notifications on Opera

Step 1: In Opera, press ALT+P to go to Settings


Step 2: In Setting search, type “Content” to go to Content Settings.

content settings

Step 3: Open Notifications:


Step 4: Do the same as you did with Google Chrome (explained below):

three dots

Eliminate Push Notifications on Safari

Step 1: Open Safari Preferences.


Step 2: Choose the domain from where you like push pop-ups gone and change to "Deny" from "Allow".

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