#StopRansomware: Cuba Ransomware

Actions to take today to mitigate cyber threats from ransomware:



• Prioritize remediating known exploited vulnerabilities.

• Train users to recognize and report phishing attempts.

• Enable and enforce phishing-resistant multifactor authentication.

Note: This joint Cybersecurity Advisory (CSA) is part of an ongoing #StopRansomware effort to publish advisories for network defenders that detail various ransomware variants and ransomware threat actors. These #StopRansomware advisories include recently and historically observed tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help organizations protect against ransomware. Visit stopransomware.gov to see all #StopRansomware advisories and to learn more about other ransomware threats and no-cost resources.

The FBI and the Cybersecurity and Infrastructure Security Agency (CISA) are releasing this joint CSA to disseminate known Cuba ransomware IOCs and TTPs associated with Cuba ransomware actors identified through FBI investigations, third-party reporting, and open-source reporting. This advisory updates the December 2021 FBI Flash: Indicators of Compromise Associated with Cuba Ransomware.

Note: While this ransomware is known by industry as “Cuba ransomware,” there is no indication Cuba ransomware actors have any connection or affiliation with the Republic of Cuba.

Since the release of the December 2021 FBI Flash, the number of U.S. entities compromised by Cuba ransomware has doubled, with ransoms demanded and paid on the increase.

This year, Cuba ransomware actors have added to their TTPs, and third-party and open-source reports have identified a possible link between Cuba ransomware actors, RomCom Remote Access Trojan (RAT) actors, and Industrial Spy ransomware actors.

FBI and CISA encourage organizations to implement the recommendations in the Mitigations section of this CSA to reduce the likelihood and impact of Cuba ransomware and other ransomware operations.

Download the PDF version of this report: pdf, 649 kb.

For a downloadable copy of IOCs, see:

• AA22-335A.stix (STIX 148 kb).
• (Updated December 12, 2022) AA22-335A-2.stix (STIX, 67 kb). (End of Update.)

Overview

Since the December 2021 release of FBI Flash: Indicators of Compromise Associated with Cuba Ransomware, FBI has observed Cuba ransomware actors continuing to target U.S. entities in the following five critical infrastructure sectors: Financial Services, Government Facilities, Healthcare and Public Health, Critical Manufacturing, and Information Technology. As of August 2022, FBI has identified that Cuba ransomware actors have:

• Compromised 101 entities, 65 in the United States and 36 outside the United States.
• Demanded 145 million U.S. Dollars (USD) and received 60 million USD in ransom payments.

Cuba Ransomware Actors’ Tactics, Techniques, and Procedures

As previously reported by FBI, Cuba ransomware actors have leveraged the following techniques to gain initial access into dozens of entities in multiple critical infrastructure sectors:

• Known vulnerabilities in commercial software [T1190]
• Phishing campaigns [T1566]
• Compromised credentials [T1078]
• Legitimate remote desktop protocol (RDP) tools [T1563.002]

After gaining initial access, the actors distributed Cuba ransomware on compromised systems through Hancitor—a loader known for dropping or executing stealers, such as Remote Access Trojans (RATs) and other types of ransomware, onto victims’ networks.

Since spring 2022, Cuba ransomware actors have modified their TTPs and tools to interact with compromised networks and extort payments from victims.[1],[2]

Cuba ransomware actors have exploited known vulnerabilities and weaknesses and have used tools to elevate privileges on compromised systems. According to Palo Alto Networks Unit 42,[2] Cuba ransomware actors have:

• Exploited CVE-2022-24521 in the Windows Common Log File System (CLFS) driver to steal system tokens and elevate privileges.
• Used a PowerShell script to identify and target service accounts for their associated Active Directory Kerberos ticket. The actors then collected and cracked the Kerberos tickets offline via Kerberoasting [T1558.003].
• Used a tool, called KerberCache, to extract cached Kerberos tickets from a host’s Local Security Authority Server Service (LSASS) memory [T1003.001].
• Used a tool to exploit CVE-2020-1472 (also known as “ZeroLogon”) to gain Domain Administrative privileges [T1068]. This tool and its intrusion attempts have been reportedly related to Hancitor and Qbot.

According to Palo Alto Networks Unit 42, Cuba ransomware actors use tools to evade detection while moving laterally through compromised environments before executing Cuba ransomware. Specifically, the actors, “leveraged a dropper that writes a kernel driver to the file system called ApcHelper.sys. This targets and terminates security products. The dropper was not signed; however, the kernel driver was signed using the certificate found in the LAPSUS NVIDIA leak." [T1562.001].[2]

In addition to deploying ransomware, the actors have used “double extortion” techniques, in which they exfiltrate victim data, and (1) demand a ransom payment to decrypt it and, (2) threaten to publicly release it if a ransom payment is not made.[2]

Cuba Ransomware Link to RomCom and Industrial Spy Marketplace

Since spring 2022, third-party and open-source reports have identified an apparent link between Cuba ransomware actors, RomCom RAT actors, and Industrial Spy ransomware actors:

• According to Palo Alto Networks Unit 42, Cuba ransomware actors began using RomCom malware, a custom RAT, for command and control (C2).[2]
• Cuba ransomware actors may also be leveraging Industrial Spy ransomware. According to third-party reporting, suspected Cuba ransomware actors compromised a foreign healthcare company. The threat actors deployed Industrial Spy ransomware, which shares distinct similarities in configuration to Cuba ransomware. Before deploying the ransomware, the actors moved laterally using Impacket and deployed the RomCom RAT and Meterpreter Reverse Shell HTTP/HTTPS proxy via a C2 server [T1090].
• Cuba ransomware actors initially used their leak site to sell stolen data; however, around May 2022, the actors began selling their data on Industrial Spy’s online market for selling stolen data.[2]

RomCom actors have targeted foreign military organizations, IT companies, food brokers and manufacturers.[3][4] The actors copied legitimate HTML code from public-facing webpages, modified the code, and then incorporated it in spoofed domains [T1584.001], which allowed the RomCom actors to:

• Host counterfeit Trojanized applications for
  • SolarWinds Network Performance Monitor (NPM),
  • KeePass password manager,
  • PDF Reader Pro, (by PDF Technologies, Inc., not an Adobe Acrobat or Reader product), and
  • Advanced IP Scanner software;
• Deploy the RomCom RAT as the final stage.

INDICATORS OF COMPROMISE

See tables 1 through 5 for Cuba ransomware IOCs that FBI obtained during threat response investigations as of late August 2022. In addition to these tables, see the publications in the References section below for aid in detecting possible exploitation or compromise.

Note: For IOCs as of early November 2021, see FBI Flash: Indicators of Compromise Associated with Cuba Ransomware.

See figure 1 for an example of a Cuba ransomware note.

Additional resources to detect possible exploitation or compromise:

• Palo Alto Networks Novel News on Cuba Ransomware: Greetings From Tropical Scorpius
• BlackBerry blog RomCom Threat Actor Abuses KeePass and SolarWinds to Target Ukraine and Potentially the United Kingdom
• BlackBerry blog Unattributed RomCom Threat Actor Spoofing Popular Apps Now Hits Ukrainian Militaries

MITRE ATT&CK TECHNIQUES

Cuba ransomware actors use the ATT&CK techniques listed in Table 6. Note: For details on TTPs listed in the table, see FBI Flash Indicators of Compromise Associated with Cuba Ransomware.

FBI and CISA recommend network defenders apply the following mitigations to limit potential adversarial use of common system and network discovery techniques and to reduce the risk of compromise by Cuba ransomware:

• Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, and secure location (i.e., hard drive, storage device, the cloud).
• Require all accounts with password logins (e.g., service account, admin accounts, and domain admin accounts) to comply with National Institute for Standards and Technology (NIST) standards for developing and managing password policies.
  • Use longer passwords consisting of at least 8 characters and no more than 64 characters in length.
  • Store passwords in hashed format using industry-recognized password managers.
  • Add password user “salts” to shared login credentials.
  • Avoid reusing passwords.
  • Implement multiple failed login attempt account lockouts.
  • Disable password “hints.”
  • Refrain from requiring password changes more frequently than once per year.
  • Note: NIST guidance suggests favoring longer passwords instead of requiring regular and frequent password resets. Frequent password resets are more likely to result in users developing password “patterns” cyber criminals can easily decipher.
  • Require administrator credentials to install software.
• Require multifactor authentication for all services to the extent possible, particularly for webmail, virtual private networks, and accounts that access critical systems.
• Keep all operating systems, software, and firmware up to date. Timely patching is one of the most efficient and cost-effective steps an organization can take to minimize its exposure to cybersecurity threats. Prioritize patching SonicWall firewall vulnerabilities and known exploited vulnerabilities in internet-facing systems. Note: SonicWall maintains a vulnerability list that includes Advisory ID, CVE, and mitigation. Their list can be found at psirt.global.sonicwall.com/vuln-list.
• Segment networks to prevent the spread of ransomware. Network segmentation can help prevent the spread of ransomware by controlling traffic flows between—and access to—various subnetworks and by restricting adversary lateral movement.
• Identify, detect, and investigate abnormal activity and potential traversal of the indicated ransomware with a networking monitoring tool. To aid in detecting the ransomware, implement a tool that logs and reports all network traffic, including lateral movement activity on a network. Endpoint detection and response (EDR) tools are particularly useful for detecting lateral connections as they have insight into common and uncommon network connections for each host.
• Install, regularly update, and enable real time detection for antivirus software on all hosts.
• Review domain controllers, servers, workstations, and active directories for new and/or unrecognized accounts.
• Audit user accounts with administrative privileges and configure access controls according to the principle of least privilege.
• Disable unused ports.
• Consider adding an email banner to emails received from outside your organization.
• Disable hyperlinks in received emails.
• Implement time-based access for accounts set at the admin level and higher. For example, the Just-in-Time (JIT) access method provisions privileged access when needed and can support enforcement of the principle of least privilege (as well as the Zero Trust model). JIT sets a network-wide policy in place to automatically disable admin accounts at the Active Directory level when the account is not in direct need. Individual users may submit their requests through an automated process that grants them access to a specified system for a set timeframe when they need to support the completion of a certain task.
• Disable command-line and scripting activities and permissions. Privilege escalation and lateral movement often depend on software utilities running from the command line. If threat actors are not able to run these tools, they will have difficulty escalating privileges and/or moving laterally.
• Maintain offline backups of data, and regularly maintain backup and restoration. By instituting this practice, the organization ensures they will not be severely interrupted, and/or only have irretrievable data.
• Ensure all backup data is encrypted, immutable (i.e., cannot be altered or deleted), and covers the entire organization’s data infrastructure.

RESOURCES

• Stopransomware.gov is a whole-of-government approach that gives one central location for ransomware resources and alerts.
• Resource to mitigate a ransomware attack: CISA-Multi-State Information Sharing and Analysis Center (MS-ISAC) Joint Ransomware Guide.
• No-cost cyber hygiene services: Cyber Hygiene Services and Ransomware Readiness Assessment.

REPORTING

FBI is seeking any information that can be shared, to include boundary logs showing communication to and from foreign IP addresses, a sample ransom note, communications with ransomware actors, Bitcoin wallet information, decryptor files, and/or a benign sample of an encrypted file.

FBI and CISA do not encourage paying ransom as payment does not guarantee victim files will be recovered. Furthermore, payment may also embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. Regardless of whether you or your organization have decided to pay the ransom, FBI and CISA urge you to promptly report ransomware incidents immediately. Report to a local FBI Field Office, or CISA at us-cert.cisa.gov/report.

DISCLAIMER

The information in this report is being provided “as is” for informational purposes only. FBI and CISA do not endorse any commercial product or service, including any subjects of analysis. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by FBI or CISA.

ACKNOWLEDGEMENTS

FBI and CISA would like to thank BlackBerry, ESET, The National Cyber-Forensics and Training Alliance (NCFTA), Palo Alto Networks, and PRODAFT for their contributions to this CSA.

December 1, 2022: Initial Version|December 12, 2022: Added new IP addresses and IOCs