Meet Interlock — The New Ransomware Targeting FreeBSD Servers
Summary:
The Interlock ransomware, a relatively new threat that emerged in late September 2024, has been targeting organizations worldwide with a distinctive tactic: it uses an encryptor specifically designed for FreeBSD servers. This is unusual, as most ransomware focuses on Linux systems, particularly VMware ESXi servers, or on Windows environments. As of October, Interlock has targeted six organizations, including Wayne County, Michigan, publishing stolen data on a leak site if the ransom is not paid—a hallmark of double-extortion. The first insights into Interlock came from incident responder Simo in early October, who discovered a new backdoor associated with the group. Soon after, MalwareHuntTeam identified what was initially thought to be a Linux ELF encryptor, which was later confirmed to be compiled for FreeBSD. Tests on a virtual machine revealed that the encryptor was specifically built for FreeBSD 10.4, but it failed to execute correctly, even on a FreeBSD VM.
Trend Micro researchers later found additional samples of the FreeBSD ELF encryptor, along with a Windows encryptor variant. The choice of FreeBSD likely reflects Interlock’s strategy of targeting critical infrastructure, where FreeBSD is commonly used for its stability and security. Trend Micro suggests this approach allows attackers to maximize disruption, as attacks on infrastructure can pressure victims to pay substantial ransoms to avoid service interruptions.
Security Officer Comments:
For communication, each victim is assigned a unique "Company ID" and instructed to use this identifier along with an email address on Interlock’s dark web negotiation site. Similar to other recent ransomware operations, the site features a chat system for direct communication between the victim and threat actors. Once inside a network, Interlock’s operators exfiltrate data from servers, then spread laterally across devices before deploying ransomware to encrypt all accessible files. This stolen data is used as leverage in a double-extortion scheme, threatening public disclosure if the ransom goes unpaid. Ransom demands vary widely, ranging from hundreds of thousands to several million dollars, based on the size of the organization.
Suggested Corrections:
Backup your data, system images, and configurations, regularly test them, and keep the backups offline: Ensure that backups are regularly tested and that they are not connected to the business network, as many ransomware variants try to find and encrypt or delete accessible backups. Maintaining current backups offline is critical because if your network data is encrypted with ransomware, your organization can restore systems.
Update and patch systems promptly: This includes maintaining the security of operating systems, applications, and firmware in a timely manner. Consider using a centralized patch management system; use a risk-based assessment strategy to drive your patch management program.
Test your incident response plan: There's nothing that shows the gaps in plans more than testing them. Run through some core questions and use those to build an incident response plan: Are you able to sustain business operations without access to certain systems? For how long? Would you turn off your manufacturing operations if business systems such as billing were offline?
Check Your Security Team's Work: Use a 3rd party pen tester to test the security of your systems and your ability to defend against a sophisticated attack. Many ransomware criminals are aggressive and sophisticated and will find the equivalent of unlocked doors.
Segment your networks: There's been a recent shift in ransomware attacks – from stealing data to disrupting operations. It's critically important that your corporate business functions and manufacturing/production operations are separated and that you carefully filter and limit internet access to operational networks, identify links between these networks, and develop workarounds or manual controls to ensure ICS networks can be isolated and continue operating if your corporate network is compromised. Regularly test contingency plans such as manual controls so that safety-critical functions can be maintained during a cyber incident.
Train employees: Email remains the most vulnerable attack vector for organizations. Users should be trained on how to avoid and spot phishing emails. Multi-factor authentication can help prevent malicious access to sensitive services.
Link(s):
https://www.bleepingcomputer.com/ne...the-new-ransomware-targeting-freebsd-servers/
The Interlock ransomware, a relatively new threat that emerged in late September 2024, has been targeting organizations worldwide with a distinctive tactic: it uses an encryptor specifically designed for FreeBSD servers. This is unusual, as most ransomware focuses on Linux systems, particularly VMware ESXi servers, or on Windows environments. As of October, Interlock has targeted six organizations, including Wayne County, Michigan, publishing stolen data on a leak site if the ransom is not paid—a hallmark of double-extortion. The first insights into Interlock came from incident responder Simo in early October, who discovered a new backdoor associated with the group. Soon after, MalwareHuntTeam identified what was initially thought to be a Linux ELF encryptor, which was later confirmed to be compiled for FreeBSD. Tests on a virtual machine revealed that the encryptor was specifically built for FreeBSD 10.4, but it failed to execute correctly, even on a FreeBSD VM.
Trend Micro researchers later found additional samples of the FreeBSD ELF encryptor, along with a Windows encryptor variant. The choice of FreeBSD likely reflects Interlock’s strategy of targeting critical infrastructure, where FreeBSD is commonly used for its stability and security. Trend Micro suggests this approach allows attackers to maximize disruption, as attacks on infrastructure can pressure victims to pay substantial ransoms to avoid service interruptions.
Security Officer Comments:
For communication, each victim is assigned a unique "Company ID" and instructed to use this identifier along with an email address on Interlock’s dark web negotiation site. Similar to other recent ransomware operations, the site features a chat system for direct communication between the victim and threat actors. Once inside a network, Interlock’s operators exfiltrate data from servers, then spread laterally across devices before deploying ransomware to encrypt all accessible files. This stolen data is used as leverage in a double-extortion scheme, threatening public disclosure if the ransom goes unpaid. Ransom demands vary widely, ranging from hundreds of thousands to several million dollars, based on the size of the organization.
Suggested Corrections:
Backup your data, system images, and configurations, regularly test them, and keep the backups offline: Ensure that backups are regularly tested and that they are not connected to the business network, as many ransomware variants try to find and encrypt or delete accessible backups. Maintaining current backups offline is critical because if your network data is encrypted with ransomware, your organization can restore systems.
Update and patch systems promptly: This includes maintaining the security of operating systems, applications, and firmware in a timely manner. Consider using a centralized patch management system; use a risk-based assessment strategy to drive your patch management program.
Test your incident response plan: There's nothing that shows the gaps in plans more than testing them. Run through some core questions and use those to build an incident response plan: Are you able to sustain business operations without access to certain systems? For how long? Would you turn off your manufacturing operations if business systems such as billing were offline?
Check Your Security Team's Work: Use a 3rd party pen tester to test the security of your systems and your ability to defend against a sophisticated attack. Many ransomware criminals are aggressive and sophisticated and will find the equivalent of unlocked doors.
Segment your networks: There's been a recent shift in ransomware attacks – from stealing data to disrupting operations. It's critically important that your corporate business functions and manufacturing/production operations are separated and that you carefully filter and limit internet access to operational networks, identify links between these networks, and develop workarounds or manual controls to ensure ICS networks can be isolated and continue operating if your corporate network is compromised. Regularly test contingency plans such as manual controls so that safety-critical functions can be maintained during a cyber incident.
Train employees: Email remains the most vulnerable attack vector for organizations. Users should be trained on how to avoid and spot phishing emails. Multi-factor authentication can help prevent malicious access to sensitive services.
Link(s):
https://www.bleepingcomputer.com/ne...the-new-ransomware-targeting-freebsd-servers/