CryptoNar Ransomware

CryptoNar is a new variant of the CryptoJoker ransomware that uses different encryption processes for different file types.

Threat ID:: CC-2607
Category:: Ransomware
Threat Severity:: Low
Threat Vector:: Phishing
Published:: 4 September 2018 12:00 AM

Report a cyber attack: call 0300 303 5222 or email [email protected]

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This article no longer conforms to NHS Digital's standards for cyber alerts, and may contain outdated or inaccurate information. Use of this information contained in this page is at your own risk

Summary

CryptoNar is a new variant of the CryptoJoker ransomware that uses different encryption processes for different file types.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

At the time of publication, CryptoNar's distribution method is unknown, however there are unconfirmed reports indicating it is being delivered via phishing campaigns.

Once CyptoNar is executed on an affected system It will fully encrypt .txt and .md files and append them with the .fully.crypto.Nar extension. All the remaining files on the system will have only the first 1024 bytes encrypted and will be appended with the .partially.cryptoNAR extension.

Remediation steps

Type	Step
	A free decryptor tools for this ransomware has been released however they are untested by NHS Digital and users can use them at their own risk. If a device 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, anti-virus 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 based on the principle 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 affected device and 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 device).

Type

Step

A free decryptor tools for this ransomware has been released however they are untested by NHS Digital and users can use them at their own risk.

If a device 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, anti-virus 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 based on the principle 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 affected device and 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 device).

Last edited: 17 February 2020 12:41 pm