Our 3-part article series continues with a detailed description and analysis of CTB-Locker. Jump to the first part dedicated to CryptoWall – the biggest ransomware family of 2015.
CTB-Locker/ Critroni Ransomware Background Check
Security researchers have observed thousands of cases of CTB-Locker infections. CTB-Locker, or as it’s also known – Critroni, was first made available on underground forums in June 2014. The name CTB-Locker stands for Curve-Tor-Bitcoin, referring to the Curve elliptic encryption scheme applied for the file encryption. We all know what Tor and Bitcoin stand for.
When it first emerged, CTB-Locker’s ransom message was available in two languages only – Russian and English. However, things changed quickly and the ransom message started appearing in other languages as well. The ransomware has targeted Italian, Dutch, German, Spanish, Latvian and French-speaking users by pretending to be a financial institution and sending out malicious attachments.
CTB-Locker Unique Features
As expected, CTB-Locker’s command & control servers are located in the Tor network. However, they don’t play much role in the initial infection. What is particularly interesting about CTB-Locker is the fact that no Internet connection is needed for the encryption process to be completed. As with the encryption, the Italian researcher Zairon (here’s his blog https://zairon.wordpress.com/) has cleared out another unique feature of CTB.
The ransomware uses an encryption which is a combination of SHA-256 and the Curve elliptic encryption method. Restoring the encrypted files is only possible with the Master key which is hosted on the attackers’ server.
CTB-Locker also offers an affiliate program where other ‘volunteers’ can join the ‘program’ and get a cut of the collected ransoms. The program is also hosted on Tor, where an updated log is kept on whatever is new with the functionalities of the ransomware.
CTB-Locker Network Behavior
We have already specified that CTB-Locker doesn’t need Internet connection in order to encrypt the user’s files. Once such connection is obtained, the ransomware will send the encryption information to the control server hosted on Tor anonymous network. To do so, CTB uses the Tor2Web service, designed to act like a proxy. Also, CTB can check online for its external IP address.
CTB-Locker File-System Behavior
As with other ransomware threats, CTB drops a ransom message on the targeted system after the encryption process has finished. The lock screen image may look like this:
Also, a pop-up application stored on the local machine can be displayed, containing instructions on the payment such as:
- A payment ID.
- A list of the encrypted files.
- A countdown counter.
A copy of the same text is stored on the file-system as a text file, together with a copy of the background image. CTB-Locker is designed to disable the Volume shadow copies on the system.
Stay tuned! Part III is coming soon! Until then, you’re welcome to join our security forums and tell us about your experience with ransomware!
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
- Guide 1: How to Remove from Windows.
- Guide 2: Get rid of on Mac OS X.
- Guide 3: Remove in Google Chrome.
- Guide 4: Erase from Mozilla Firefox.
- Guide 5: Uninstall from Microsoft Edge.
- Guide 6: Remove from Safari.
- Guide 7: Eliminate from Internet Explorer.
- Guide 8: Disable Push Notifications in Your Browsers.
How to Remove from Windows.
Step 1: Boot Your PC In Safe Mode to isolate and remove
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.
Step 3: Clean any registries, created by on your computer.
The usually targeted registries of Windows machines are the following:
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:
Get rid of from Mac OS X.
Step 1: Uninstall and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
- 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:
You can repeat the same procedure with the following other Library directories:
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.
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.
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.
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.
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".
Step 4: After that, select the 'Extensions' Tab.
Step 5: Click once on the extension you want to remove.
Step 6: Click 'Uninstall'.
A pop-up window will appear asking for confirmation to uninstall the extension. Select 'Uninstall' again, and the will be removed.
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”:
Step 3: Click “Content Settings”:
Step 4: Open “Notifications”:
Step 5: Click the three dots and choose Block, Edit or Remove options:
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”
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.
Step 3: Open Notifications:
Step 4: Do the same as you did with Google Chrome (explained below):
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".