Threat Explorer

The Threat Explorer is a comprehensive resource consumers can turn to for daily, accurate, up-to-date information on the latest threats, risks and vulnerabilities.

Ransom.PClock

Ransom.PClock

Discovered:
05 January 2015
Updated:
30 August 2016
Also Known As:
Trojan.Ransomcrypt.P [Symantec]
Infection Length:
Varies
Systems Affected:
Windows
Ransom.PClock is a Trojan horse that encrypts files on the compromised computer and demands payment to decrypt the files.

Note: Definitions prior to August, 2016 may detect this threat as Trojan.Ransomcrypt.P

Antivirus Protection Dates

  • Initial Rapid Release version 05 January 2015 revision 018
  • Latest Rapid Release version 29 August 2016 revision 024
  • Initial Daily Certified version 05 January 2015 revision 036
  • Latest Daily Certified version 30 August 2016 revision 009
  • Initial Weekly Certified release date 07 January 2015
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
Once executed, the Trojan creates the following files:
  • %UserProfile%\Application Data\WinCL\wincl.exe
  • %UserProfile%\Application Data\WinCL\wincl.jpg
  • %UserProfile%\Application Data\WinCL\enc_files.txt
  • %UserProfile%\Application Data\WinCL\last_chance.txt

The Trojan then creates the following registry entry so that it runs every time Windows starts:
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"wincl" = "%UserProfile%\Application Data\WinCL\wincl.exe"

Next, the Trojan creates the following registry subkeys:
  • HKEY_CURRENT_USER\Software\VB and VBA Program Settings\CLOCK\SData
  • HKEY_CURRENT_USER\Software\VB and VBA Program Settings\CLOCK\EData

The Trojan then attempts to encrypt files with any of the following extensions:
  • .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

The Trojan then deletes any shadow copies the operating system may have made of the encrypted files.

Next, the Trojan contacts the following legitimate website in order to find out the current value of a bitcoin:
  • https://blockchain.info

The Trojan then connects to the following remote location:
  • [http://]invisioncorp.com.au

It may then download an update of itself from the following remote location:
  • [http://]invisioncorp.com.au/scripts/wl/cl.[REMOVED]

Next, the Trojan uses the following image file to change the desktop wallpaper:
  • %UserProfile%\Application Data\WinCL\wincl.jpg

The Trojan then displays a message with the following text:

"Your Personal Files Are Encrypted!

Your personal files encryption *produced on this computer: photos, videos, /documents, etc. Encryption was produced using a public key RSA-2048 generated for this computer.
To decrypt files you need to obtain the single copy of the private key, which will allow to decrypt the files, located n a secret server on the Internet; the server will destroy the key after a time specified in this window. After that, nobody and never will be able to restore files...

To obtain the private key for this computer, which will automatically decrypt files, you need to pay [calculated] bitcoin (~300 USD). You can easily delete this software, but know that without it, you will never be able to get your original files back.
For more information on how to buy and send bitcoins, click "Pay with Bitcoin".
To open a list of encoded files, click "Show files".
Disable your antivirus to prevent the removal of this software.
Do not delete this list, it will be used for decryption. And do not move your files."

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
You may have arrived at this page either because you have been alerted by your Symantec product about this risk, or you are concerned that your computer has been affected by this risk.

Before proceeding further we recommend that you run a full system scan . If that does not resolve the problem you can try one of the options available below.



FOR NORTON USERS
If you are a Norton product user, we recommend you try the following resources to remove this risk.


Removal Tool

If you have an infected Windows system file, you may need to replace it using the Windows installation CD .


How to reduce the risk of infection
The following resources provide further information and best practices to help reduce the risk of infection.


FOR BUSINESS USERS
If you are a Symantec business product user, we recommend you try the following resources to remove this risk.


Identifying and submitting suspect files
Submitting suspicious files to Symantec allows us to ensure that our protection capabilities keep up with the ever-changing threat landscape. Submitted files are analyzed by Symantec Security Response and, where necessary, updated definitions are immediately distributed through LiveUpdate™ to all Symantec end points. This ensures that other computers nearby are protected from attack. The following resources may help in identifying suspicious files for submission to Symantec.


Removal Tool

If you have an infected Windows system file, you may need to replace it using the Windows installation CD .


How to reduce the risk of infection
The following resource provides further information and best practices to help reduce the risk of infection.
Protecting your business network



MANUAL REMOVAL
The following instructions pertain to all current Symantec antivirus products.


1. Performing a full system scan
How to run a full system scan using your Symantec product


2. Restoring settings in the registry
Many risks make modifications to the registry, which could impact the functionality or performance of the compromised computer. While many of these modifications can be restored through various Windows components, it may be necessary to edit the registry. See in the Technical Details of this writeup for information about which registry keys were created or modified. Delete registry subkeys and entries created by the risk and return all modified registry entries to their previous values.
Writeup By: Paul Mangan