CryptoMix Ransomware

A new ransomware variant of CryptoMix has been discovered named Mole ransomware.

Threat ID:: CC-1336
Category:: Ransomware
Threat Severity:: Medium
Threat Vector:: Phishing
Published:: 20 April 2017 12:00 AM

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Summary

A new ransomware variant of CryptoMix has been discovered named Mole ransomware.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - all versions

Threat details

The ransomware is distributed through spam emails appearing to be shipping notifications. The campaign uses social engineering techniques to make the user install the ransomware.

The campaign highlights that a package has not been delivered and then directs the user to a URL, suggesting that it contains additional information relating to the undelivered package. The link directs the user to a fake Microsoft Word online site with a warning that states; “This document cannot be read in your browser” and requires a plugin to be installed. When the user clicks the download button a file is executed and the Mole ransomware is installed.

After installation the User Account Control (UAC) prompt will ask the user to user to allow a certain command to run. When ‘Yes’ is clicked the ransomware is launched with administrative privileges in addition to generating a unique hexadecimal ID for the compromised user.

The ransomware disables the Windows startup recovery as well as deleting shadow copies of documents on the device. This process prevents or makes the process of recovering lost files more challenging.

Threat updates

Date	Update
10 May 2017	Updates A new ransomware variant of CryptoMix/ CryptFile2 has been discovered that is now using the .WALLET extension for encrypted files other ransomware families previously used .WALLET as an extension including Dharma, Crysis and Sanctions. CryptoMix, nicknamed ‘Wallet ransomware’ will generate a unique 16 hexadecimal victim ID and an encryption key on the computer and will send this information back to the command and control (C2) server. It will then begin the process of encrypting (AES encryption) any files it detects that are not located in certain whitelisted folders; Windows, packages, cookies, application data etc. Instead of the ransom note being its typical HTML version, it will display an ‘Application Error’ and if the user selects ‘OK’, the ransomware will use WMI Command-line Utility to launch an elevated version of the ransomware. Another fake alert will pop up, this time a User Account Control (UAC) notification to allow WMI Command-line Utility to run. Selecting ‘Yes’ will execute commands to disable the Windows startup recovery and clear the Windows Shadow Volume Copies – disabling the ability to use the backed up data.

Date

Update

10 May 2017

Updates

A new ransomware variant of CryptoMix/ CryptFile2 has been discovered that is now using the .WALLET extension for encrypted files other ransomware families previously used .WALLET as an extension including Dharma, Crysis and Sanctions.

CryptoMix, nicknamed ‘Wallet ransomware’ will generate a unique 16 hexadecimal victim ID and an encryption key on the computer and will send this information back to the command and control (C2) server. It will then begin the process of encrypting (AES encryption) any files it detects that are not located in certain whitelisted folders; Windows, packages, cookies, application data etc.

Instead of the ransom note being its typical HTML version, it will display an ‘Application Error’ and if the user selects ‘OK’, the ransomware will use WMI Command-line Utility to launch an elevated version of the ransomware. Another fake alert will pop up, this time a User Account Control (UAC) notification to allow WMI Command-line Utility to run. Selecting ‘Yes’ will execute commands to disable the Windows startup recovery and clear the Windows Shadow Volume Copies – disabling the ability to use the backed up data.

Remediation steps

Type	Step
	If a computer on your network becomes infected with ransomware it will begin encrypting local machine files and files on any network the logged-in user has permission to access. For system administration accounts this may include backup storage locations. To avoid becoming infected with ransomware, ensure that: A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails. All operating systems, antivirus and other security products are kept up to date. All day to day computer activities such as email and internet are performed using non-administrative accounts and that permissions are always assigned on the basis of least privilege. Your organisation adopts a holistic all round approach to Cyber Security as advocated by the 10 Steps To Cyber Security. Identifying the source of infection: Identifying the infected machine and unplugging / disconnecting or quarantining it from the network is essential to damage limitation. Users should immediately report infections to their IT support provider, disconnect their network cable and power the computer down. File auditing should be enabled and file server logs should be monitored to detect signs of unauthorised encryption and allow the source of encryption to be identified (i.e. the infected PC). To limit the damage of ransomware and enable recovery: All critical data must be backed up, and these backups must be sufficiently protected/kept out of reach of ransomware. Multiple backups should be created including at least one off-network backup (e.g. to tape). The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup.

Type

Step

If a computer on your network becomes infected with ransomware it will begin encrypting local machine files and files on any network the logged-in user has permission to access. For system administration accounts this may include backup storage locations.

To avoid becoming infected with ransomware, ensure that:

A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails.
All operating systems, antivirus and other security products are kept up to date.
All day to day computer activities such as email and internet are performed using non-administrative accounts and that permissions are always assigned on the basis of least privilege.
Your organisation adopts a holistic all round approach to Cyber Security as advocated by the 10 Steps To Cyber Security.

Identifying the source of infection:
Identifying the infected machine and unplugging / disconnecting or quarantining it from the network is essential to damage limitation.

Users should immediately report infections to their IT support provider, disconnect their network cable and power the computer down.
File auditing should be enabled and file server logs should be monitored to detect signs of unauthorised encryption and allow the source of encryption to be identified (i.e. the infected PC).

To limit the damage of ransomware and enable recovery:
All critical data must be backed up, and these backups must be sufficiently protected/kept out of reach of ransomware.

Multiple backups should be created including at least one off-network backup (e.g. to tape).

The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup.

Last edited: 11 January 2022 4:43 pm