PClock4 virus, also known as PClock SysGop ransomware, is the latest iteration of the PClock ransomware family.
PClock ransomware virus has been around for quite some time. Previous infection campaigns were using the XOR algorithm to encrypt the user’s data. A previous PClock version of the ransomware family was also pretending to be Cryptolocker, relying on the famous ransomware’s name and fame. This old infection was reported to ask for 0.5 Bitcoin in exchange for file decryption. Let’s see what has been changed in PClock4 ransomware virus, in the table below:
Threat Summary
| Name | PClock4 |
| Type | ScreenLock Ransomware |
| Short Description | PClock4, also known as PClock SysGop, uses the RSA-2048 encryption algorithm and targets a total of 2630 file type extensions. Reportedly it demands a ransom of 0.6 – 1.6 Bitcoin. |
| Symptoms | The victim’s files are encrypted. A screen locker function is embedded in the source code of PClock4 which gets in the way of any user activity on the targeted machine. A ransom message is displayed. For full text of the message, see the article. |
| Distribution Method | Spam emails. |
| Detection Tool | See If Your System Has Been Affected by PClock4 Download Malware Removal Tool |
| User Experience | Join our forum to Discuss PClock4. |
| 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. |
Unfortunately, in October researchers reported that there was no longer a way to decrypt newer PClock variants without the original decryption key possessed by criminals. The free decrypter coded by Fabian Wosar got broken when the ransomware authors updated their code. However, there still may be a chance for you to obtain access to your encrypted data via using powerful data recovery software or via data back ups.
There is no guarantee software data recovery attempts will be successful but in some cases users have shared positive results in restoring data partially. You will find data recovery solutions at the end of this article, where you will also be instructed on how to remove PClock both manually and automatically.
PClock 4 Ransomware Distribution Method
PClock4 has been reported to spread mainly in spam email campaigns. Such campaigns tend to become more intensive during the winter holidays season when people are less aware of potential online infections. The ransomware’s payload may be hiding in attached files appearing to be sent by legal organizations. Here are two examples of subject lines of PClock4 spam campaign:
- PLEASE READ YOUR FAX T6931
- Criminal case against you
Researchers report that the malware is attached in WSF files which contain the payload dropper – Crimace Trojan.
More particularly,a RAR archive contains a WSF file. When users download and open the archive, and execute the WSF file, a JScript function is set to initiate a series of operations that download and run a malware known as Crimace, known to be detected as TrojanDownloader:JS/Crimace.A.
The Trojan is a malware downloader, that connects to an online server and downloads and runs other malware such as PClock4. Other malware can be distributed the same way, too.
Besides being sent out in aggressive spam and phishing campaigns, the ransomware may be distributed in exploit kit operations.
PClock4 Ransomware – Further Technical Analysis
By comparing screenshots of PClock4 previous campaigns and the latest one described here, we will see that not much has changed. In other words, the ransomware hasn’t evolved, or at least no big changes have been observed. Here is an example of the latest campaign, provided by Microsoft:
The ransomware has been detected by Microsoft as Ransom:Win32/WinPlock.B or WinPlock, and is more commonly referred to as PClock. The first infections of the crypto virus were observed in 2015.
Emsisoft security researcher Fabian Wosar was able to create a decrypter for the earlier versions that enabled users to decrypt their files for free. Unfortunately, this is not the case any longer, as cybercriminals updated their code in May 2015 and broke the decrypter. The only way for PClock victims was to restore encrypted data from backup files or by paying the ransom, which is never recommended as it doesn’t guarantee any success. After all, don’t forget you are dealing with cybercriminals.
Interestingly, despite being known for more than 2 years, PClock has remained an entry-level operation even in the PClock4 iteration. The ransomware still requires its victims to get in contact with the authors via email, which is an ancient tactic. The only change in PClock4 appears to be the number of files targeted for encryption – it has jumped from 100+ files types, to 2,630.
Remove PClock4 and Restore Encrypted Files
PClock4 can be removed manually – the first half of PClock4 removal manual below will guide you through the process but keep in mind at least some experience in malware removal is needed. If you don’t feel confident enough, please refer to the instructions for PClock4 automatic removal.
