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Remove CryptoWall 4.0 and Restore the Encrypted Files

Unfortunately, the most devastating ransomware virus has already released a new version and has outrun our predictions for 2016. A prevalent number of researchers have labeled this latest variant CryptoWall 4.0, even though it’s still unclear whether it’s CryptoWall 4.0 or just a point release.

Nonetheless, the security community is very aware of what its previous version CryptoWall 3.0 and its HELP_DECRYPT files did to computers worldwide – damages of over 18 million USD per year. Now, a new version has been reported to encrypt user files and leave a ransom note with instructions on how to decrypt them – a typical CryptoWall behavior. What is different is that this version may use stronger encryption algorithm and is reported to be extremely difficult to hack.

Name CryptoWall 4.0
Type Ransomware Trojan
Short Description This devastating infection encrypts user files and asks payment for decryption which is sent to cyber criminals.
Symptoms Cryptowall 4.0 may leave files named “HELP_YOUR_FILES” with .txt, .html, .png extensions containing ransom instructions.The user may see their files of the PC with changed names as well as extensions.
Distribution Method Phishing and Spam emails, attachments (ZIP and script files), others.
Detection Tool Download Malware Removal Tool, to See If Your System Has Been Affected by CryptoWall 4.0
User Experience Join our forum to follow the discussion about CryptoWall 4.0.
Data Recovery Tool Windows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive.
Data Recovery Tool Windows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive.

Cryptowall 4.0 – How Did I Get It?

This cyber-attack is reported to be spreading via several different methods and it aims to extort users for their money.

One method to spread is via email. We are talking about spam mail campaigns such as the notorious Windows 10 free upgrade spam, which resembles a message from Microsoft, for example. Users report email attacks associated with .ZIP attachments as well as links to malicious URLs.

Other forms of mail attacks are called email spoofing and phishing and they are more common with targeted attacks. Spoofing masks the sender’s email address as a person or an organization within the user’s familiar email addresses.

There is also a possibility you may have been redirected to a malicious online link by having an adware program on your computer. Adware programs mostly come as extensions to your browser bundled with free programs downloaded from software providing websites or torrent engines.

Cryptowall 4.0 – How Does It Work?

Once you have been infected with the ransomware, it may begin creating several different malicious files in Windows XP, Vista, 7, 8, 8.1 and 10:

C:\Documents and Settings\My Documents\Downloads\analytics.exe
C:\Documents and Settings\Administrator\ApplcationData\29780b04\f5de21f429.exe
C:\Documents and Settings\Administrator\ApplcationData\29780b04\

It also may modify the following Windows files:

C:\Documents and Settings\Administrator\Cookies\index.dat
C:\Documents and Settings\Adminstrator\Local Settings\History\History.IE5\index.dat
C:\Documents and Settings\Adminstrator\Local Settings\Temporary Internet Files\Content.IE5\Index.dat
C:\WINDOWS\Debug\UserMode\ChkAcc.bak
C:\WINDOWS\Debug\UserMode\ChkAcc.log
C:\WINDOWS\system32\CatRoot2\edb.chk
C:\WINDOWS\system32\CatRoot2\edb.log
C:\WINDOWS\system32\CatRoot2\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}\catdb
C:\WINDOWS\system32\wbem\Logs\FrameWork.log

These files may be programmed to scan for user data, stop PC protection(Windows Firewall, antivirus software), user tracking and others. The devastating virus may also create the following registry entries for its malicious files to run on the next system start-up in the following registry locations:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32\OpenSaveMRU\*
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32\OpenSaveMRU\exe
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\ShellNoRoam\MUICache
HKEY_USERS\S-1-5-21-430184907-3966876259-3679084233-500\Software\Microsoft\CurrentVersion\Explorer\ComDlg32\OpenSaveMRU*
HKEY_USERS\S-1-5-21-430184907-3966876259-3679084233-500\Software\Microsoft\CurrentVersion\Explorer\ComDlg32\OpenSaveMRU\exe
HKEY_USERS\S-1-5-21-430184907-3966876259-3679084233-500\Software\Microsoft\CurrentVersion\Run
HKEY_USERS\S-1-5-21-430184907-3966876259-3679084233-500\Software\Microsoft\ShellNoRoam\MUICache

The virus then might begin to scan your computer for the most used file types main of which may be:

.exe, .pdf, .docx, .xls, .txt, .doc, .jpg, .bmp, .psd, .vdi, .swf, mp3, .mp4

The ransomware then may encrypt all of the user files and what is worse with this 4.0 variant is that it may use different file extensions (for example: NA7EP, 3A, A2 for different files) and it may also change the name of the files, additionally confusing the user. The files encrypted by this vile threat may vary from hundreds to thousands, depending on how many and how important files the user stores on his/her PC.

After encrypting the files with a strong, almost impossible to crack encryption, this vile threat then begins to create the following files in different folders. (may be%Appdata% %Local% %Desktop% %Users%):

HELP_YOUR_FILES.TXT
HELP_YOUR_FILES.HTML
HELP_YOUR_FILES.PNG

These files contain the instructions for how to pay the ransom. Infected users report seeing this message:
cryptowall-4-ransomware-help-your-files-html

Cryptowall 3.0 Similarities

What is reported to be the same as with its previous version, is that 4.0 remains to its roots and uses botnet (zombie) computers which are already infected with it to conduct its attacks. Furthermore, once activated, it may establish connection to the following domains to download the malicious executables:

pastimefoods (.) com;19bee88 (.)Com;adrive62 (.) com;httthanglong (.) com;mofiaweb (.) com;image camera club(.) com;vk1001 (.) rutuvestir (.) com;parsimaj (.) com;frc-pr (.) com;www.frc-pr (.)com;adcconsulting (.)net

Also, version 4.0 still uses a very strong encryption algorithm that has a decryption key for the files and it can only be decrypted with the specific decryption service, provided by the attackers.
Cryptowall-virus-decrypt-files
The ransomware still uses Tor networking in its instructions since Tor is still anonymous and protects the ransom payment process.

Unlike CryptoWall 3.0, Cryptowall 4.0 ransomware has become even more cunning, tricking enhanced firewall protection installed on the victim computer. The ransomware has also been reported to still demand a high ransom payment and entertainingly to mock users that they have become a part of the #Cryptowall community.

Security researchers strongly advise users not to pay the ransom since they fund the next ransomware operation of the cyber-crooks. It is also never a guarantee that they will receive the decryption keys. Even though Cryptowall decryption algorithm has been proven to be almost impossible to decrypt, there have been new ways that are continuously developing into hacking a computer using different out-of-the box methods. You can read more about it here and you can also try to decrypt your data using the tutorials provided after this article. But to decrypt files, it is important to remove this devastating threat first.

Removing Cryptowall 4.0 Completely from Your Computer

Since the ransomware is essentially a Trojan horse, it is important to first isolate it before removing it. Experts usually use Live OS booting to scan and remove malware such as Trojans from infected PCs, however you may also be able to remove CryptoWall by using Safe Mode and scanning your computer with it, instructions for which you can find below. Also, it is highly advisable to not try to remove the threat manually and use an Advanced anti-malware tool to scan and detect all of the associated CryptoWall 4.0 files automatically. Make sure you back up all your files, on an external device, such as a USB drive or external SSD while in Safe Mode. The ransomware may have scripts that delete files automatically in case its own malicious files are being removed.

In case your files have been encrypted with the .jpg extension you can find more information in the article on how to Remove CryptoWall RSA-4096 Variant and Restore .jpg Encrypted Files

When you boot into safe mode, make sure you have active connection to the web, since the anti-malware tool needs it to update and perform an effective scan.
Here is how to remove Cryptowall 4.0 Ransomware from your Computer:

1. Boot Your PC In Safe Mode to isolate and remove CryptoWall 4.0
2. Remove CryptoWall 4.0 with SpyHunter Anti-Malware Tool
3. Back up your data to secure it against infections and file encryption by CryptoWall 4.0 in the future
Optional: Using Alternative Anti-Malware Tools

Restoring Files Encrypted by CryptoWall 4.0

Cryptowall encryption is considered to be near-impossible to decrypt. However, the good news is that it may have several different variants which may use different decyrption methods that are easier to decrypt. In order to try and directly break the encryption, please refer to the following methods mentioned hereafter:

Method 1:

http://sensorstechforum.com/restore-files-encrypted-via-rsa-encryption-remove-cryptowall-and-other-ransomware-manually/

Method 2:

http://sensorstechforum.com/remove-rsa-2048-encryption-key-from-cryptowall-3-0/

Method 3:

Use file recovery software:

NOTE! Substantial notification about the CryptoWall 4.0 threat: Manual removal of CryptoWall 4.0 requires interference with system files and registries. Thus, it can cause damage to your PC. Even if your computer skills are not at a professional level, don’t worry. You can do the removal yourself just in 5 minutes, using a malware removal tool.

Vencislav Krustev

A network administrator and malware researcher at SensorsTechForum with passion for discovery of new shifts and innovations in cyber security. Strong believer in basic education of every user towards online safety.

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