Night Sky Ransomware: In-Depth Analysis, Detection, Mitigation, and Removal

Summary of Night Sky Ransomware

Night Sky is a China-based ransomware actor which emerged in late 2021.  Night Sky targets corporate networks and engages in multi- extortion – demanding payment for decryption tools, as well as for the non-release of stolen data.  The group hosts a blog listing names of non-paying victims, alongside their leaked data. Early Night Sky attacks were focused on targets in Japan and Bangladesh.  Night Sky ransomware operates as a “RaaS” or Ransomware-as-a-service.

Night Sky Ransomware

What Does Night Sky Ransomware Target?

Night Sky ransomware operators target a variety of industries, including healthcare, finance, government, education, and manufacturing.

How Does Night Sky Ransomware Spread?

Night Sky ransomware is typically spread through malicious emails or malicious websites. These malicious emails usually contain malicious attachments, links to malicious websites, or malicious JavaScript code. Operators of Night Sky ransomware have also utilized Cobalt Strike or Log4Shell exploitation to achieve initial access into targets.

Night Sky Ransomware Technical Details

Night Sky operates as a ransomware service (RaaS). Affiliates are required to handle delivery and initial access of the payloads on their own, meaning delivery or movement can vary depending on the needs of the attacker and the state of the target environment. Upon infection, affected files are branded with a “.nightsky” extension. Actual file encryption is handled via a combination of AES-128 (CBC) and RSA2048 (RSA public keys, file encryption via AES). Many observed Night Sky ransomware samples are obfuscated via VMProtect – a common and commercial “code protection” application. Night Sky’s encryption process is quite rapid, however, critical directories are omitted from the process to ensure stability during exfiltration. For example, all .EXE and .DLL files are left unencrypted; similar case with the Windows directory and other critical system paths.

How to Detect Night Sky Ransomware

  • The SentinelOne Singularity XDR Platform can identify and stop any malicious activities and items related to Night Sky ransomware.

In case you do not have SentinelOne deployed, detecting ransomware requires a combination of technical and operational measures designed to identify and flag suspicious activity on the network. This allows the organization to take appropriate action, and to prevent or mitigate the impact of the ransomware attack.

To mitigate the risk of this Ransomware without SentinelOne deployed, it is important to take a multi-layered approach, which includes the following steps:

  1. Use anti-malware software or other security tools capable of detecting and blocking known ransomware variants. These tools may use signatures, heuristics, or machine learning algorithms, to identify and block suspicious files or activities.
  2. Monitor network traffic and look for indicators of compromise, such as unusual network traffic patterns or communication with known command-and-control servers.
  3. Conduct regular security audits and assessments to identify network and system vulnerabilities and ensure that all security controls are in place and functioning properly.
  4. Educate and train employees on cybersecurity best practices, including identifying and reporting suspicious emails or other threats.
  5. Implement a robust backup and recovery plan to ensure that the organization has a copy of its data and can restore it in case of an attack.

How to Mitigate Night Sky Ransomware

  • The SentinelOne Singularity XDR Platform can return systems to their original state using either the Repair or Rollback feature.

If you do not have SentinelOne deployed, there are several steps that organizations can take to mitigate the risk of Night Sky ransomware attacks.

Educate Employees

Employees should be educated on the risks of ransomware, and on how to identify and avoid phishing emails, malicious attachments, and other threats. They should be encouraged to report suspicious emails or attachments, and to avoid opening them, or clicking on links or buttons in them.

Implement Strong Passwords

Organizations should implement strong, unique passwords for all user accounts, and should regularly update and rotate these passwords. Passwords should be at least 8 characters long, and should include a combination of uppercase and lowercase letters, numbers, and special characters.

Enable Multi-factor Authentication

Organizations should enable multi-factor authentication (MFA) for all user accounts, to provide an additional layer of security. This can be done through the use of mobile apps, such as Google Authenticator or Microsoft Authenticator, or through the use of physical tokens or smart cards.

Update and Patch Systems

Organizations should regularly update and patch their systems, to fix any known vulnerabilities, and to prevent attackers from exploiting them. This includes updating the operating system, applications, and firmware on all devices, as well as disabling any unnecessary or unused services or protocols.

Implement Backup and Disaster Recovery

Organizations should implement regular backup and disaster recovery (BDR) processes, to ensure that they can recover from ransomware attacks, or other disasters. This includes creating regular backups of all data and systems, and storing these backups in a secure, offsite location.

The backups should be tested regularly, to ensure that they are working, and that they can be restored quickly and easily.

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