Grief

Grief Ransomware: In-Depth Analysis, Detection, and Mitigation

Summary of Grief Ransomware

The Grief ransomware (aka PayOrGrief)  operation emerged in May 2021.  Grief targets corporate networks and engages in multi- extortion – demanding payment for decryption tools, as well as for the non-release of stolen data.  Grief ransomware is an evolution of the DoppelPaymer / BitPaymer families.

What Does Grief Ransomware Target?

Grief ransomware primarily targets the healthcare, financial services, entertainment, government and education industries.  Limited SMB (small to medium-sized businesses) targeting has been observed.

How Does Grief Ransomware Spread?

Grief ransomware is deployed in multiple ways: via Cobalt Strike or a similar framework, and through email phishing. Additionally, brute force attacks against RDP services have been seen in Grief campaigns.

Grief Ransomware Technical Details

Grief ransomware payloads are an evolution of the Dopplepaymer family, and contain similar functionality.  Grief campaigns begin with RDP brute-force attacks or  a phishing/spear phishing email to a target. In the case of a phishing attack, the targeted user receives a malicious email, an encoded text file is downloaded containing additional commands and instructions. Once infected, exfiltration, lateral movement, and eventually the deployment of ransomware can occur. Grief operators are adept at utilizing COTS (Commercial off the Shelf) tools and LOLBins (Living off the Land) to perform internal reconnaissance and traversal.

Encryption is achieved via a combination of RSA-2048 and AES-256.  Internal string encryption for Grief ransomware is handled via RSA-2048 and AES-256 as well, with an RC4 key length 48 bytes.  This is identical to that of Dopplepaymer, with only an 8-byte difference between the RC4 key length.

How to Detect Grief Ransomware

• The SentinelOne Singularity XDR Platform can identify and stop any malicious activities and items related to Grief 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 Grief Ransomware

• The SentinelOne Singularity XDR Platform can return systems to their original state (which is free from re-infection) using either the Repair or Rollback feature.

In case you do not have SentinelOne deployed, there are several steps that organizations can take to mitigate the risk of ransomware attacks:

1. 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.
2. 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.
3. 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.
4. 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.