CryptoLocker’s Copycats. Decrypt Files Encrypted by PClock - How to, Technology and PC Security Forum |

CryptoLocker’s Copycats. Decrypt Files Encrypted by PClock

NamePClock Ransomware
Short DescriptionA file-encrypting threat that demands payment in Bitcoins and locks the victims’ desktops.
SymptomsA ransomware message on the desktop.
Distribution MethodPossibly drive-by downloads, spam email attachments, unsafe browsing.
Detection toolDownload SpyHunter, to See If Your System Has Been Affected By PClock Ransomware
Data Recovery ToolWindows 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.

In the past couple of years, ransomware attacks have reached skyrocket levels. To many people, especially security researchers, common tax payers/ victims and corporations, ransomware has turned into a nightmare. Among all of the file-encrypting pieces, there are particularly two that seem to outshine them all – CryptoWall and CryptoLocker. ransom-message-cryptolocker-pclock

CryptoLocker, however, has proven to be quite the shapeshifter, with all of its versions and copycats. Just recently, the PClock has been awakened. It is indeed a CryptoLocker imitator and has frustrated too many users since the beginning of 2015.

Copycat Numer One: PClock

PClock was discovered several months ago but has been recently reactivated. The malicious threat masquerades itself as CryptoLocker. Even though it is not CryptoLocker, it still encrypts the user’s data and asks for payment in BitCoin. Researchers named the ‘virus’ PClock because of a project name located inside the malware executable. Back in January, the Cryptolocker copycat ‘s distribution technique was not yet unveiled. Most likely, it is distributed via other malware pieces that infiltrate the system in a stealthy manner – Trojans and backdoors which can grant remote access any time they wish.

Once the encryption process is completed and the files with particular extensions are affected, the victim will be presented with a ransom screen and a 72-hour countdown.

The types of files and their extensions encrypted by PClock are:

→.3fr, .accdb, .ai, .arw, .bay, .cdr, .cer, .cr2, .crt, .crw, .dbf, .dcr, .der, .dng, .doc, .docm, .docx, .dwg, .dxf, .dxg, .eps, .erf, .indd, .jpe, .jpg, .kdc,.mdb, .mdf, .mef, .mrw, .nef, .nrw, .odb, .odm, .odp, .ods, .odt, .orf, .p12, .p7b, .p7c, .pdd, .pef, .pem, .pfx, .ppt, .pptm, .pptx, .psd, .pst, .ptx, .r3d,.raf, .raw, .rtf, .rw2, .rwl, .srf, .srw, .wb2, .wpd, .wps, .xlk, .xls, .xlsb, .xlsm, .xlsx

PClock: Contamination Path and Malicious Process

Once the ransomware is installed, its files will be found in:


WinCL.exe is where the primary file is located.

Even if the victim succeeds to terminate the WinCL.exe process, the encrypted files will unfortunately stay this way. PClock is also known to change the victim’s desktop to the ‘extortion’ message with instructions to pay the ransom and acquire a decryption key. Paying the ransomware will not necessarily lead to the files’ safe restoration. Interestingly, there are rare occasions when cyber crooks turn out to be quite cooperative and lower the ransom amount (very rare).

Furthermore, PClock is designed to delete Shadow Volume Copies by issuing the following command:

→vssadmin Delete Shadows /All /Quiet

After the Shadow Volume Copies have been deleted, the malicious software will continuously check bitcoin software to see if a payment has been finalized. If so, it will automatically turn into a decryptor tool and grant instructions to the victim.

Copycat Number Two: CryptoDefense

Similar to CryptoLocker, CryptoDefense is distributed primarily via spam email campaigns. It pretends to use the RSA-2048 encryption algorithm, claiming that once encrypted, the user’s files will no longer be accessible. However, that claim later turned out not to be true.

The main difference between the two ransomware pieces is that CryptoLocker generates the RSA encryption and decryption keys on the Command & Control server. CryptoDefense employs the Windows CryptoAPI application. Windows CryptoAPI, however, is ‘equipped’ with several aberrations that, obviously, were not known by CryptoDefense’s creators – it creates local copies of the RSA keys on the victim’s compute. Hence, the key to decrypt the encrypted files is on the affected system.

How to Decrypt Files Encrypted by PClock and CryptoDefense?

Luckily, a solution is found for those two – a decryptor developed by Fabian Wosar
Fabian Wosar of Emsisoft was able to create a decryptor for files encrypted by PClock and other CryptoLocker –like ransomware pieces. Unfortunately, later versions of the threats are most likely ‘fixed’ against such solutions.
To keep away from ransomware, be sure to sustain a valid copy of anti-virus software on your machine. Many of the recent malware pieces are quite stealthy and may reside in the system until activated remotely. To bypass contamination:

  • Avoid suspicious websites… or at least be very cautious while ‘unsafely’ browsing the Web.
  • Don’t open unknown email attachments and filter your emails.
  • Don’t allow access to unknown publishers.
  • Make sure all of your software is up to date – OS, browsers, plug-ins, etc and keep in mind that cyber crooks’ favorite is to exploit various software vulnerabilities.


Ransomware Prevention and Protection. File Backup

In case you have suspicions that your system has been targeted by malware, you can scan it immediately via anti-malware software of your choice and likings.

Also, here are easy step-by-step instructions to enable the Microsoft Windows Defense

feature to backup your files and have the ability to restore them immediately to an

earlier state before their encryption:

1) Download a particular anti-malware scanner and remove the PClock Ransomware files from the computer.

2) Open Properties by right-clicking on My Computer

and then choosing it.

properties (1)

3) Open Advanced System Settings


4) Go to System Protection.

5) Mark the HDD partition on which you have necessary files, and you want to defend.

6) Click Configure and then click on Turn On System


7) Click OK and you are all set

After you have this protection switched on, if something happens to your data, you

may be able to restore them, using those steps:

1) Right-Click the encrypted file and then choose Properties.

2) Click the Previous Versions button.

3) At this point, you should see an earlier version of the file with a ‘last

modified’ date.

4) Mark the file with the mouse and then choose the down-right button that says



If your files were previously encrypted, this software might leave some files, such

as registry values and others on your system. This is why, recommendations are to

download a particular anti-malware program that will ensure your protection and

terminate any traces of the malicious software.


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

Milena Dimitrova

An inspired writer and content manager who has been with SensorsTechForum for 4 years. Enjoys ‘Mr. Robot’ and fears ‘1984’. 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!

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