Nemty Ransomware

Nemty is a newly observed ransomware tool believed to be targeting European and CIS countries.

Threat ID:: CC-3194
Category:: Adware
Threat Severity:: Low
Threat Vector:: Insecure network
Published:: 29 August 2019 12:00 AM

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

Summary

Nemty is a newly observed ransomware tool believed to be targeting European and CIS countries.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

At the time of publication, it is unclear how Nemty is delivered, although there are unconfirmed reports indicating it may be distributed via compromised Remote Desktop Services connections.

Once installed, Nemty will check the default language before sending user and system information to a command and control server. It will then attempt to encrypt all non-system files using an unknown algorithm.

Update 9 Sep 2019

Further details regarding Nemty's delivery methods have come to light. The latest variant (1.4) is delivered by the RIG exploit kit via spoofed versions of legitimate websites. Unlike previous versions, this variant will not target CIS countries.

Update 17 Sep 2019

The latest variant of Nemty, version 1.4, is now being distributed by the Radio exploit kit alongside RIG.

Update 17 Oct 2019

The latest Nemty version - 1.6 - has been observed in the wild being delivered by the RIG exploit kit. This variant uses the standard Windows cryptographic libraries in place of previous Nemty variant's custom AES implementation.

Update 06 Nov 2019

A new Trik campaign has been observed delivering Nemty 1.6 one exposed SMB ports using an updated list of default credentials

Remediation steps

Type	Step
	If Remote Desktop Protocol (RDP) is not used, then ensure port 3389 (TCP/UDP) is blocked at your internet firewall. If RDP is used, then: Ensure network level authentication is enabled. Only allow access for authorised RDP users. Enforce strong password policies. Enforce multi-factor authentication. Don't allow RDP access for privileged user accounts. Don’t use generic accounts. Set user accounts with an expiry date. Audit user accounts periodically. Only allow point-to-point connections from specific IP addresses where feasible. Ensure Transport Layer Security (TLS) is up-to-date. Log and monitor all RDP activity and investigate unusual behaviour. Consider only allowing RDP for authorised virtual private network (VPN) connections. 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). 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. Update 17 Oct 2019 An open-source decryption tool has been released that is able to recover files encrypted by Nemty versions 1.4 to 1.6. Please note that NHS Digital do not test or verify such tools and organisations use them at their own risk.

Type

Step

If Remote Desktop Protocol (RDP) is not used, then ensure port 3389 (TCP/UDP) is blocked at your internet firewall. If RDP is used, then:

Ensure network level authentication is enabled.
Only allow access for authorised RDP users.
Enforce strong password policies.
Enforce multi-factor authentication.
Don't allow RDP access for privileged user accounts.
Don’t use generic accounts.
Set user accounts with an expiry date.
Audit user accounts periodically.
Only allow point-to-point connections from specific IP addresses where feasible.
Ensure Transport Layer Security (TLS) is up-to-date.
Log and monitor all RDP activity and investigate unusual behaviour.
Consider only allowing RDP for authorised virtual private network (VPN) connections.

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).

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.

Update 17 Oct 2019

An open-source decryption tool has been released that is able to recover files encrypted by Nemty versions 1.4 to 1.6. Please note that NHS Digital do not test or verify such tools and organisations use them at their own risk.

Last edited: 11 January 2022 1:29 pm