CrossLock

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

What Is CrossLock Ransomware?

CrossLock ransomware emerged in early 2023 as a multi-extortion group with a TOR-based blog site hosting victim names and data. CrossLock ransomware payloads are written in Go. The payloads contain some more advanced features including an expanded command-line syntax, as well as event tracing bypasses (ETW bypasses).

What Does CrossLock Ransomware Target?

To date, CrossLock ransomware attacks have been focused on targets in South America. The group is known to target entities within the manufacturing and agriculture/farming industries.

How Does CrossLock Ransomware Work?

Recent CrossLock ransomware payloads mimic processes from Cybereason, an endpoint security company.

The CrossLock payload encryption relies on standard GoLang packages, working through a combination of ChaCha20 and Curve25519 (ECC). The ransomware will attempt to stop specific services or processes which may inhibit the encryption process. This varies slightly across samples. Further, the ransomware will exclude specific file names and extensions so as not to corrupt the core OS, or its own processes and artifacts.

Standard excluded file names include ntuserl.dat, desktop.ini, pagefile.sys, swapfile.sys, bootmg, bootnxt, dumpstack.log, dumpstack.log.tmp. Standard excluded extensions include .dll, .exe, .sys, .html, .htm, .bak, .lnk, .bat, .cmd

Commands supported by CrossLock include:

If the threat actor omits the use of command-line arguments, the payload will simply attempt to encrypt the local device including all available volumes and files.

Upon infection, users are instructed to contact the attacker via TOX Messenger for further instructions. Affected files are given the “.lock” extension. The ransom notes, “-CrossLock_readme_to_Decrypt-.txt”, or very similar are written to each folder containing the encrypted files.

CrossLock will also attempt to inhibit the recovery of infected systems by removing Volume Shadow Copies (VSS) along with clearing Windows Event Logs (wevtutil.exe) and deleting System Backup States via wbaddmain.exe. System recovery is disabled also via bcdedit.exe.

How to Detect CrossLock Ransomware

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

In case you do not have SentinelOne deployed, detecting CrossLock 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 detect CrossLock 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 CrossLock Ransomware

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

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