Cuba Ransomware Uses Veeam Exploit Against Critical U.S. Organizations

Cyber Security Threat Summary:
The Cuba ransomware group has been observed launching attacks against critical infrastructure organizations in the US and IT firms in Latin America. They utilize a mix of both old and new tools. In early June 2023, Blackberry’s Threat Research and Intelligence Team identified this recent campaign. They have noted that Cuba now uses CVE-2023-27543 to extract credentials from configuration files. This vulnerability affects Veeam Backup & Replication (VBR) products and has had an exploit available since March 2023. Previously, WithSecure had reported that FIN7, a group linked to multiple ransomware activities, had been actively exploiting CVE-2023-27543.

According to Blackberry’s findings, Cuba seems to gain initial access through compromised admin credentials via RDP, avoiding brute force methods. Following this, Cuba’s unique custom downloader known as ‘BugHatch’ establishes contact with the command-and-control server, fetching DLL files or carrying out command executions.

“An initial foothold on the target environment is achieved through a Metasploit DNS stager that decrypts and runs shellcode directly in memory. Cuba utilizes the now-widespread BYOVD (Bring Your Own Vulnerable Driver) technique to turn off endpoint protection tools. Also, it uses the 'BurntCigar' tool to terminate kernel processes associated with security products. Apart from the Veeam flaw that's relatively recent, Cuba also exploits CVE-2020-1472 ("Zerologon"), a vulnerability in Microsoft's NetLogon protocol, which gives them privilege escalation against AD domain controllers. In the post-exploitation phase, Cuba was observed using Cobalt Strike beacons and various "lolbins." (BleepingComputer, 2023).

Security Officer Comments:
Researchers highlight the evident financial drive of the Cuba ransomware faction and notes that the threat actor is probably of Russian origin, a supposition that is mirrored in previous cyber intelligence reports. This presumption is founded on the exclusion of machines using Russian keyboard layouts from infections, discovery of Russian 404 error pages on sections of its infrastructure, linguistic cues, and the group’s focus on Western targets. Ultimately, the Cuba ransomware group remains an active menace, a notable occurrence for ransomware operations lasting about four years. The incorporation of CVE-2023-27543 into Cuba’s list of targets emphasizes the urgency of swiftly applying security updates for Veeam. This once again underscores the hazard of postponing updates, particularly when proof of concept exploits are publicly accessible.

Suggested Correction(s):
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 how to avoid and spot phishing emails. Multi Factor authentication can help prevent malicious access to sensitive services.