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ALERTES DE SÉCURITÉ

ALERTES DE SÉCURITÉ

ALERTES DE SÉCURITÉ

#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities

detail historically and recently 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 about other ransomware threats and no-cost resources.

The United States National Security Agency (NSA), the U.S. Federal Bureau of Investigation (FBI), the U.S. Cybersecurity and Infrastructure Security Agency (CISA), the U.S. Department of Health and Human Services (HHS), the Republic of Korea (ROK) National Intelligence Service (NIS), and the ROK Defense Security Agency (DSA) (hereafter referred to as the “authoring agencies”) are issuing this joint Cybersecurity Advisory (CSA) to highlight ongoing ransomware activity against Healthcare and Public Health Sector organizations and other critical infrastructure sector entities.

This CSA provides an overview of Democratic People’s Republic of Korea (DPRK) state-sponsored ransomware and updates the July 6, 2022, joint CSA North Korean State-Sponsored Cyber Actors Use Maui Ransomware to Target the Healthcare and Public Health Sector. This advisory highlights TTPs and IOCs DPRK cyber actors used to gain access to and conduct ransomware attacks against Healthcare and Public Health (HPH) Sector organizations and other critical infrastructure sector entities, as well as DPRK cyber actors’ use of cryptocurrency to demand ransoms.

The authoring agencies assess that an unspecified amount of revenue from these cryptocurrency operations supports DPRK national-level priorities and objectives, including cyber operations targeting the United States and South Korea governments—specific targets include Department of Defense Information Networks and Defense Industrial Base member networks. The IOCs in this product should be useful to sectors previously targeted by DPRK cyber operations (e.g., U.S. government, Department of Defense, and Defense Industrial Base). The authoring agencies highly discourage paying ransoms as doing so does not guarantee files and records will be recovered and may pose sanctions risks.

For additional information on state-sponsored DPRK malicious cyber activity, see CISA’s North Korea Cyber Threat Overview and Advisories webpage.

Download the PDF version of this report: pdf, 661 kb.

For a downloadable copy of IOCs, see

AA23-040A STIX XML (XML, 196.24 KB )

TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 12. See MITRE ATT&CK for Enterprise for all referenced tactics and techniques.

This CSA is supplementary to previous reports on malicious cyber actor activities involving DPRK ransomware campaigns—namely Maui and H0lyGh0st ransomware. The authoring agencies are issuing this advisory to highlight additional observed TTPs DPRK cyber actors are using to conduct ransomware attacks targeting South Korean and U.S. healthcare systems.

Observable TTPs

The TTPs associated with DPRK ransomware attacks include those traditionally observed in ransomware operations. Additionally, these TTPs span phases from acquiring and purchasing infrastructure to concealing DPRK affiliation:

  • Acquire Infrastructure [T1583]. DPRK actors generate domains, personas, and accounts; and identify cryptocurrency services to conduct their ransomware operations. Actors procure infrastructure, IP addresses, and domains with cryptocurrency generated through illicit cybercrime, such as ransomware and cryptocurrency theft.
  • Obfuscate Identity. DPRK actors purposely obfuscate their involvement by operating with or under third-party foreign affiliate identities and use third-party foreign intermediaries to receive ransom payments.
  • Purchase VPNs and VPSs [T1583.003]. DPRK cyber actors will also use virtual private networks (VPNs) and virtual private servers (VPSs) or third-country IP addresses to appear to be from innocuous locations instead of from DPRK.
  • Gain Access [TA0001]. Actors use various exploits of common vulnerabilities and exposures (CVE) to gain access and escalate privileges on networks. Recently observed CVEs that actors used to gain access include remote code execution in the Apache Log4j software library (known as Log4Shell) and remote code execution in unpatched SonicWall SMA 100 appliances [T1190 and T1133]. Observed CVEs used include:
  • CVE 2021-44228
  • CVE-2021-20038
  • CVE-2022-24990

Actors also likely spread malicious code through Trojanized files for “X-Popup,” an open source messenger commonly used by employees of small and medium hospitals in South Korea [T1195].

The actors spread malware by leveraging two domains: xpopup.pe[.]kr and xpopup.com. xpopup.pe[.]kr is registered to IP address 115.68.95[.]128 and xpopup[.]com is registered to IP address 119.205.197[.]111. Related file names and hashes are listed in table 1.

Table 1: Malicious file names and hashes spread by xpopup domains
File Name MD5 Hash
xpopup.rar 1f239db751ce9a374eb9f908c74a31c9
X-PopUp.exe 6fb13b1b4b42bac05a2ba629f04e3d03
X-PopUp.exe cf8ba073db7f4023af2b13dd75565f3d
xpopup.exe 4e71d52fc39f89204a734b19db1330d3
x-PopUp.exe 43d4994635f72852f719abb604c4a8a1
xpopup.exe 5ae71e8440bf33b46554ce7a7f3de666
  • Move Laterally and Discovery [TA0007, TA0008]. After initial access, DPRK cyber actors use staged payloads with customized malware to perform reconnaissance activities, upload and download additional files and executables, and execute shell commands [T1083, T1021]. The staged malware is also responsible for collecting victim information and sending it to the remote host controlled by the actors [TA0010].
  • Employ Various Ransomware Tools [TA0040]. Actors have used privately developed ransomware, such as Maui and H0lyGh0st [T1486]. Actors have also been observed using or possessing publically available tools for encryption, such as BitLocker, Deadbolt, ech0raix, GonnaCry, Hidden Tear, Jigsaw, LockBit 2.0, My Little Ransomware, NxRansomware, Ryuk, and YourRansom [T1486]. In some cases, DPRK actors have portrayed themselves as other ransomware groups, such as the REvil ransomware group. For IOCs associated with Maui and H0lyGh0st ransomware usage, please see Appendix B.
  • Demand Ransom in Cryptocurrency. DPRK cyber actors have been observed setting ransoms in bitcoin [T1486].
  • Actors are known to communicate with victims via Proton Mail email accounts. For private companies in the healthcare sector, actors may threaten to expose a company’s proprietary data to competitors if ransoms are not paid. Bitcoin wallet addresses possibly used by DPRK cyber actors include:
    • 1MTHBCrBKYEthfa16zo9kabt4f9jMJz8Rm
    • bc1q80vc4yjgg6umedkut3e9mhehxl4q4dcjjyzh59
    • 1J8spy62o7z2AjQxoUpiCGnBh5cRWKVWJC
    • 16ENLdHbnmDcEV8iqN4vuyZHa7sSdYRh76
    • bc1q3wzxvu8yhs8h7mlkmf7277wyklkah9k4sm9anu
    • bc1q8xyt4jxhw7mgqpwd6qfdjyxgvjeuz57jxrvgk9
    • 1NqihEqYaQaWiZkPVdSMiTbt7dTy1LMxgX
    • bc1qxrpevck3pq1yzrx2pq2rkvkvy0jnm56nzjv6pw
    • 14hVKm7Ft2rxDBFTNkkRC3kGstMGp2A4hk
    • 1KCwfCUgnSy3pzNX7U1i5NwFzRtth4bRBc
    • 16sYqXancDDiijcuruZecCkdBDwDf4vSEC
    • 1N6JphHFaYmYaokS5xH31Z67bvk4ykd9CP
    • LZ1VNJfn6mWjPzkCyoBvqWaBZYXAwn135
    • 1KmWW6LgdgykBBrSXrFu9kdoHz95Fe9kQF
    • 1FX4W9rrG4F3Uc7gJ18GCwGab8XuW8Ajy2
    • bc1qlqgu2l2kms5338zuc95kxavctzyy0v705tpvyc
    • bc1qy6su7vrh7ts5ng2628escmhr98msmzg62ez2sp
    • bc1q8t69gpxsezdcr8w6tfzp3jeptq4tcp2g9d0mwy
    • bc1q9h7yj79sqm4t536q0fdn7n4y2atsvvl22m28ep
    • bc1qj6y72rk039mqpgtcy7mwjd3eum6cx6027ndgmd
    • bc1qcp557vltuu3qc6pk3ld0ayagrxuf2thp3pjzpe
    • bc1ql8wsflrjf9zlusauynzjm83mupq6c9jz9vnqxg
    • bc1qx60ec3nfd5yhsyyxkzkpts54w970yxj84zrdck
    • bc1qunqnjdlvqkjuhtclfp8kzkjpvdz9qnk898xczp
    • bc1q6024d73h48fnhwswhwt3hqz2lzw6x99q0nulm4
    • bc1qwdvexlyvg3mqvqw7g6l09qup0qew80wjj9jh7x
    • bc1qavrtge4p7dmcrnvhlvuhaarx8rek76wxyk7dgg
    • bc1qagaayd57vr25dlqgk7f00nhz9qepqgnlnt4upu
    • bc1quvnaxnpqlzq3mdhfddh35j7e7ufxh3gpc56hca
    • bc1qu0pvfmtxawm8s99lcjvxapungtsmkvwyvak6cs
    • bc1qg3zlxxhhcvt6hkuhmqml8y9pas76cajcu9ltdl
    • bc1qn7a3g23nzpuytchyyteyhkcse84cnylznl3j32
    • bc1qhfmqstxp3yp9muvuz29wk77vjtdyrkff4nrxpu
    • bc1qnh8scrvuqvlzmzgw7eesyrmtes9c5m78duetf3
    • bc1q7qry3lsrphmnw3exs7tkwzpvzjcxs942aq8n0y
    • bc1qcmlcxfsy0zlqhh72jvvc4rh7hvwhx6scp27na0
    • bc1q498fn0gauj2kkjsg35mlwk2cnxhaqlj7hkh8xy
    • bc1qnz4udqkumjghnm2a3zt0w3ep8fwdcyv3krr3jq
    • bc1qk0saaw7p0wrwla6u7tfjlxrutlgrwnudzx9tyw
    • bc1qyue2pgjk09ps7qvfs559k8kee3jkcw4p4vdp57
    • bc1q6qfkt06xmrpclht3acmq00p7zyy0ejydu89zwv
    • bc1qmge6a7sp659exnx78zhm9zgrw88n6un0rl9trs
    • bc1qcywkd7zqlwmjy36c46dpf8cq6ts6wgkjx0u7cn

MITIGATIONS

Note: These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the U.S. National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. For more information on the CPGs, including additional recommended baseline protections, see cisa.gov/cpg.

The authoring agencies urge HPH organizations to:

  • Limit access to data by authenticating and encrypting connections (e.g., using public key infrastructure certificates in virtual private network (VPN) and transport layer security (TLS) connections) with network services, Internet of Things (IoT) medical devices, and the electronic health record system [CPG 3.3].
  • Implement the principle of least privilege by using standard user accounts on internal systems instead of administrative accounts [CPG 1.5], which grant excessive system administration privileges.
  • Turn off weak or unnecessary network device management interfaces, such as Telnet, SSH, Winbox, and HTTP for wide area networks (WANs) and secure with strong passwords and encryption when enabled.
  • Protect stored data by masking the permanent account number (PAN) when displayed and rendering it unreadable when stored—through cryptography, for example.
  • Secure the collection, storage, and processing practices for personally identifiable information (PII)/protected health information (PHI), per regulations such as the Health Insurance Portability and Accountability Act of 1996 (HIPAA). Implementing HIPAA security measures could prevent the introduction of malware to the system [CPG 3.4].
    • Secure PII/ PHI at collection points and encrypt the data at rest and in transit using technologies, such as TLS. Only store personal patient data on internal systems that are protected by firewalls, and ensure extensive backups are available.
    • Create and regularly review internal policies that regulate the collection, storage, access, and monitoring of PII/PHI.
  • Implement and enforce multi-layer network segmentation with the most critical communications and data resting on the most secure and reliable layer [CPG 8.1].
  • Use monitoring tools to observe whether IoT devices are behaving erratically due to a compromise [CPG 3.1].

In addition, the authoring agencies urge all organizations, including HPH Sector organizations, to apply the following recommendations to prepare for and mitigate ransomware incidents:

  • Maintain isolated backups of data, and regularly test backup and restoration [CPG 7.3]. These practices safeguard an organization’s continuity of operations or at least minimize potential downtime from a ransomware incident and protect against data losses.
    • Ensure all backup data is encrypted, immutable (i.e., cannot be altered or deleted), and covers the entire organization’s data infrastructure.
  • Create, maintain, and exercise a basic cyber incident response plan and associated communications plan that includes response procedures for a ransomware incident [CPG 7.1, 7.2].
  • Install updates for operating systems, software, and firmware as soon as they are released [CPG 5.1]. Timely patching is one of the most efficient and cost-effective steps an organization can take to minimize its exposure to cybersecurity threats. Regularly check for software updates and end-of-life notifications and prioritize patching known exploited vulnerabilities. Consider leveraging a centralized patch management system to automate and expedite the process.
  • If you use Remote Desktop Protocol (RDP), or other potentially risky services, secure and monitor them closely [CPG 5.4].
    • Limit access to resources over internal networks, especially by restricting RDP and using virtual desktop infrastructure. After assessing risks, if RDP is deemed operationally necessary, restrict the originating sources, and require phishing-resistant multifactor authentication (MFA) to mitigate credential theft and reuse [CPG 1.3]. If RDP must be available externally, use a VPN, virtual desktop infrastructure, or other means to authenticate and secure the connection before allowing RDP to connect to internal devices. Monitor remote access/RDP logs, enforce account lockouts after a specified number of attempts to block brute force campaigns, log RDP login attempts, and disable unused remote access/RDP ports [CPG 1.1, 3.1].
    • Ensure devices are properly configured and that security features are enabled. Disable ports and protocols not in use for a business purpose (e.g., RDP Transmission Control Protocol port 3389).
    • Restrict the Server Message Block (SMB) protocol within the network to only access necessary servers and remove or disable outdated versions of SMB (i.e., SMB version 1). Threat actors use SMB to propagate malware across organizations.
    • Review the security posture of third-party vendors and those interconnected with your organization. Ensure all connections between third-party vendors and outside software or hardware are monitored and reviewed for suspicious activity [CPG 5.6, 6.2].
    • Implement application control policies that only allow systems to execute known and permitted programs [CPG 2.1].
    • Open document readers in protected viewing modes to help prevent active content from running.
  • Implement a user training program and phishing exercises [CPG 4.3] to raise awareness among users about the risks of visiting websites, clicking on links, and opening attachments. Reinforce the appropriate user response to phishing and spearphishing emails.
  • Require phishing-resistant MFA for as many services as possible [CPG 1.3]—particularly for webmail, VPNs, accounts that access critical systems, and privileged accounts that manage backups.
  • Use strong passwords [CPG 1.4] and avoid reusing passwords for multiple accounts. See CISA Tip Choosing and Protecting Passwords and National Institute of Standards and Technology (NIST) Special Publication 800-63B: Digital Identity Guidelines for more information.
  • Require administrator credentials to install software [CPG 1.5].
  • Audit user accounts with administrative or elevated privileges [CPG 1.5] and configure access controls with least privilege in mind.
  • Install and regularly update antivirus and antimalware software on all hosts.
  • Only use secure networks. Consider installing and using a VPN.
  • Consider adding an email banner to messages coming from outside your organizations [CPG 8.3] indicating that they are higher risk messages.
  • Consider participating in CISA’s no-cost Automated Indicator Sharing (AIS) program to receive real-time exchange of machine-readable cyber threat indicators and defensive measures.

If a ransomware incident occurs at your organization:

  • Follow your organization’s ransomware response checklist.
  • Scan backups. If possible, scan backup data with an antivirus program to check that it is free of malware. This should be performed using an isolated, trusted system to avoid exposing backups to potential compromise.
  • U.S. organizations: Follow the notification requirements as outlined in your cyber incident response plan. Report incidents to appropriate authorities; in the U.S., this would include the FBI at a local FBI Field Office, CISA at cisa.gov/report, or the U.S. Secret Service (USSS) at a USSS Field Office.
  • South Korean organizations: Please report incidents to NIS, KISA (Korea Internet & Security Agency), and KNPA (Korean National Police Agency).
  • Apply incident response best practices found in the joint Cybersecurity Advisory, Technical Approaches to Uncovering and Remediating Malicious Activity, developed by CISA and the cybersecurity authorities of Australia, Canada, New Zealand, and the United Kingdom.

RESOURCES

Stairwell provided a YARA rule to identify Maui ransomware, and a Proof of Concept public RSA key extractor at the following link:
https://www.stairwell.com/news/threat-research-report-maui-ransomware/

REQUEST FOR INFORMATION

The FBI is seeking any information that can be shared, to include boundary logs showing communication to and from foreign IP addresses, bitcoin wallet information, the decryptor file, and/or benign samples of encrypted files. As stated above, the authoring agencies discourage paying ransoms. Payment does not guarantee files will be recovered and may embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. However, the agencies understand that when victims are faced with an inability to function, all options are evaluated to protect shareholders, employees, and customers.

Regardless of whether you or your organization decide to pay a ransom, the authoring agencies urge you to promptly report ransomware incidents using the contact information above.

ACKNOWLEDGEMENTS

NSA, FBI, CISA, and HHS would like to thank ROK NIS and DSA for their contributions to this CSA.

Disclaimer of endorsement

The information and opinions contained in this document are provided "as is" and without any warranties or guarantees. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the United States Government, and this guidance shall not be used for advertising or product endorsement purposes.

Trademark recognition

Microsoft Threat Intelligence Center is a registered trademark of Microsoft Corporation. Apache®, Sonicwall, and Apache Log4j are trademarks of Apache Software Foundation. TerraMaster Operating System is a registered trademark of Octagon Systems.

Purpose

This document was developed in furtherance of the authors’ cybersecurity missions, including their responsibilities to identify and disseminate threats, and to develop and issue cybersecurity specifications and mitigations. This information may be shared broadly to reach all appropriate stakeholders.

Appendix A: CVE Details
CVE-2021-44228     CVSS 3.0: 10 (Critical)
Vulnerability Description
Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.
Recommended Mitigations
Apply patches provided by vendor and perform required system updates.
Detection Methods
See vendors’ Guidance For Preventing, Detecting, and Hunting for Exploitation of the Log4j 2 Vulnerability.
Vulnerable Technologies and Versions
There are numerous vulnerable technologies and versions associated with CVE-2021-44228. For a full list, please check https://nvd.nist.gov/vuln/detail/CVE-2021-44228.
See https://nvd.nist.gov/vuln/detail/CVE-2021-44228 for more information.
CVE-2021-20038     CVSS 3.0: 9.8 (Critical)
Vulnerability Description
A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote unauthenticated attacker to potentially execute code as a 'nobody' user in the appliance. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.
Recommended Mitigations
Apply all appropriate vendor updates
Upgrade to:
  • SMA 100 Series - (SMA 200, 210, 400, 410, 500v (ESX, Hyper-V, KVM, AWS, Azure):
  • SonicWall SMA100 build versions 10.2.0.9-41sv or later
  • SonicWall SMA100 build versions 10.2.1.3-27sv or later

System administrators should refer to the SonicWall Security Advisories in the reference section to determine affected applications/systems and appropriate fix actions.

Support for 9.0.0 firmware ended on 10/31/2021. Customers still using that firmware are requested to upgrade to the latest 10.2.x versions.

Vulnerable Technologies and Versions
Sonicwall Sma 200 Firmware 10.2.0.8-37Sv
Sonicwall Sma 200 Firmware 10.2.1.1-19Sv
Sonicwall Sma 200 Firmware 10.2.1.2-24Sv
Sonicwall Sma 210 Firmware 10.2.0.8-37Sv
Sonicwall Sma 210 Firmware 10.2.1.1-19Sv
Sonicwall Sma 210 Firmware 10.2.1.2-24Sv
Sonicwall Sma 410 Firmware 10.2.0.8-37Sv
Sonicwall Sma 410 Firmware 10.2.1.1-19Sv
Sonicwall Sma 410 Firmware 10.2.1.2-24Sv
Sonicwall Sma 400 Firmware 10.2.0.8-37Sv
Sonicwall Sma 400 Firmware 10.2.1.1-19Sv
Sonicwall Sma 400 Firmware 10.2.1.2-24Sv
Sonicwall Sma 500V Firmware 10.2.0.8-37Sv
Sonicwall Sma 500V Firmware 10.2.1.1-19Sv
Sonicwall Sma 500V Firmware 10.2.1.2-24Sv
See https://nvd.nist.gov/vuln/detail/CVE-2021-20038 for more information.
CVE-2022-24990    CVSS 3.x: N/A
Vulnerability Description
The TerraMaster OS Unauthenticated Remote Command Execution via PHP Object Instantiation Vulnerability is characterized by scanning activity targeting a flaw in the script enabling a remote adversary to execute commands on the target endpoint. The vulnerability is created by improper input validation of the webNasIPS component in the api.php script and resides on the TNAS device appliances' operating system where users manage storage, backup data, and configure applications. By exploiting the script flaw a remote unauthenticated attacker can pass specially crafted data to the application and execute arbitrary commands on the target system. This may result in complete compromise of the target system, including the exfiltration of information. TNAS devices can be chained to acquire unauthenticated remote code execution with highest privileges.
Recommended Mitigations
Install relevant vendor patches. This vulnerability was patched in TOS version 4.2.30
Vulnerable Technologies and Versions
TOS v 4.2.29
See https://octagon.net/blog/2022/03/07/cve-2022-24990-terrmaster-tos-unauthenticated-remote-command-execution-via-php-object-instantiation/ and https://forum.terra-master.com/en/viewtopic.php?t=3030 for more information.
Appendix B: Indicators of Compromise (IOCs)

The IOC section includes hashes and IP addresses for the Maui and H0lyGh0st ransomware variants—as well as custom malware implants assumedly developed by DPRK cyber actors, such as remote access trojans (RATs), loaders, and other tools—that enable subsequent deployment of ransomware. For additional Maui IOCs, see joint CSA North Korean State-Sponsored Cyber Actors Use Maui Ransomware to Target the Healthcare and Public Health Sector.

Table 2 lists MD5 and SHA256 hashes associated with malware implants, RATs, and other tools used by DPRK cyber actors, including tools that drop Maui ransomware files.

Table 2: File names and hashes of malicious implants, RATs, and tools
MD5Hash SHA256Hash
079b4588eaa99a1e802adf5e0b26d8aa f67ee77d6129bd1bcd5d856c0fc5314169b946d32b8abaa4e680bb98130b38e7
0e9e256d8173854a7bc26982b1dde783 --
12c15a477e1a96120c09a860c9d479b3 6263e421e397db821669420489d2d3084f408671524fd4e1e23165a16dda2225
131fc4375971af391b459de33f81c253 --
17c46ed7b80c2e4dbea6d0e88ea0827c b9af4660da00c7fa975910d0a19fda072031c15fad1eef935a609842c51b7f7d
1875f6a68f70bee316c8a6eda9ebf8de 672ec8899b8ee513dbfc4590440a61023846ddc2ca94c88ae637144305c497e7
1a74c8d8b74ca2411c1d3d22373a6769 ba8f9e7afe5f78494c111971c39a89111ef9262bf23e8a764c6f65c818837a44
1f6d9f8fbdbbd4e6ed8cd73b9e95a928 4f089afa51fd0c1b2a39cc11cedb3a4a326111837a5408379384be6fe846e016
2d02f5499d35a8dffb4c8bc0b7fec5c2 830207029d83fd46a4a89cd623103ba2321b866428aa04360376e6a390063570
2e18350194e59bc6a2a3f6d59da11bd8 655aa64860f1655081489cf85b77f72a49de846a99dd122093db4018434b83ae
3bd22e0ac965ebb6a18bb71ba39e96dc 6b7f566889b80d1dba4f92d5e2fb2f5ef24f57fcfd56bb594978dffe9edbb9eb
40f21743f9cb927b2c84ecdb7dfb14a6 5081f54761947bc9ce4aa2a259a0bd60b4ec03d32605f8e3635c4d4edaf48894
4118d9adce7350c3eedeb056a3335346 5b7ecf7e9d0715f1122baf4ce745c5fcd769dee48150616753fec4d6da16e99e
43e756d80225bdf1200bc34eef5adca8 afb2d4d88f59e528f0e388705113ae54b7b97db4f03a35ae43cc386a48f263a0
47791bf9e017e3001ddc68a7351ca2d6 863b707873f7d653911e46885e261380b410bb3bf6b158daefb47562e93cb657
505262547f8879249794fc31eea41fc6 f32f6b229913d68daad937cc72a57aa45291a9d623109ed48938815aa7b6005c
5130888a0ad3d64ad33c65de696d3fa2 c92c1f3e77a1876086ce530e87aa9c1f9cbc5e93c5e755b29cad10a2f3991435
58ad3103295afcc22bde8d81e77c282f 18b75949e03f8dcad513426f1f9f3ca209d779c24cd4e941d935633b1bec00cb
5be1e382cd9730fbe386b69bd8045ee7 5ad106e333de056eac78403b033b89c58b4c4bdda12e2f774625d47ccfd3d3ae
5c6f9c83426c6d33ff2d4e72c039b747 a3b7e88d998078cfd8cdf37fa5454c45f6cbd65f4595fb94b2e9c85fe767ad47
640e70b0230dc026eff922fb1e44c2ea 6319102bac226dfc117c3c9e620cd99c7eafbf3874832f2ce085850aa042f19c
67f4dad1a94ed8a47283c2c0c05a7594 3fe624c33790b409421f4fa2bb8abfd701df2231a959493c33187ed34bec0ae7
70652edadedbacfd30d33a826853467d 196fb1b6eff4e7a049cea323459cfd6c0e3900d8d69e1d80bffbaabd24c06eba
739812e2ae1327a94e441719b885bd19 6122c94cbfa11311bea7129ecd5aea6fae6c51d23228f7378b5f6b2398728f67
76c3d2092737d964dfd627f1ced0af80 bffe910904efd1f69544daa9b72f2a70fb29f73c51070bde4ea563de862ce4b1
802e7d6e80d7a60e17f9ffbd62fcbbeb 87bdb1de1dd6b0b75879d8b8aef80b562ec4fad365d7abbc629bcfc1d386afa6
827103a6b6185191fd5618b7e82da292 --
830bc975a04ab0f62bfedf27f7aca673 --
85995257ac07ae5a6b4a86758a2283d7 --
85f6e3e3f0bdd0c1b3084fc86ee59d19 f1576627e8130e6d5fde0dbe3dffcc8bc9eef1203d15fcf09cd877ced1ccc72a
87a6bda486554ab16c82bdfb12452e8b 980bb08ef3e8afcb8c0c1a879ec11c41b29fd30ac65436495e69de79c555b2be
891db50188a90ddacfaf7567d2d0355d 0837dd54268c373069fc5c1628c6e3d75eb99c3b3efc94c45b73e2cf9a6f3207
894de380a249e677be2acb8fbdfba2ef --
8b395cc6ecdec0900facf6e93ec48fbb --
92a6c017830cda80133bf97eb77d3292 d1aba3f95f11fc6e5fec7694d188919555b7ff097500e811ff4a5319f8f230be
9b0e7c460a80f740d455a7521f0eada1 45d8ac1ac692d6bb0fe776620371fca02b60cac8db23c4cc7ab5df262da42b78
9b9d4cb1f681f19417e541178d8c75d7 f5f6e538001803b0aa008422caf2c3c2a79b2eeee9ddc7feda710e4aba96fea4
a1f9e9f5061313325a275d448d4ddd59 dfdd72c9ce1212f9d9455e2bca5a327c88d2d424ea5c086725897c83afc3d42d
a452a5f693036320b580d28ee55ae2a3 99b0056b7cc2e305d4ccb0ac0a8a270d3fceb21ef6fc2eb13521a930cea8bd9f
a6e1efd70a077be032f052bb75544358 3b9fe1713f638f85f20ea56fd09d20a96cd6d288732b04b073248b56cdaef878
ad4eababfe125110299e5a24be84472e a557a0c67b5baa7cf64bd4d42103d3b2852f67acf96b4c5f14992c1289b55eaa
b1c1d28dc7da1d58abab73fa98f60a83 38491f48d0cbaab7305b5ddca64ba41a2beb89d81d5fb920e67d0c7334c89131
b6f91a965b8404d1a276e43e61319931 --
bdece9758bf34fcad9cba1394519019b 9d6de05f9a3e62044ad9ae66111308ccb9ed2ee46a3ea37d85afa92e314e7127
c3850f4cc12717c2b54753f8ca5d5e0e 99b448e91669b92c2cc3417a4d9711209509274dab5d7582baacfab5028a818c
c50b839f2fc3ce5a385b9ae1c05def3a 458d258005f39d72ce47c111a7d17e8c52fe5fc7dd98575771640d9009385456
cf236bf5b41d26967b1ce04ebbdb4041 60425a4d5ee04c8ae09bfe28ca33bf9e76a43f69548b2704956d0875a0f25145
d0e203e8845bf282475a8f816340f2e8 f6375c5276d1178a2a0fe1a16c5668ce523e2f846c073bf75bb2558fdec06531
ddb1f970371fa32faae61fc5b8423d4b dda53eee2c5cb0abdbf5242f5e82f4de83898b6a9dd8aa935c2be29bafc9a469
f2f787868a3064407d79173ac5fc0864 92adc5ea29491d9245876ba0b2957393633c9998eb47b3ae1344c13a44cd59ae
fda3a19afa85912f6dc8452675245d6b 56925a1f7d853d814f80e98a1c4890b0a6a84c83a8eded34c585c98b2df6ab19
-- 0054147db54544d77a9efd9baf5ec96a80b430e170d6e7c22fcf75261e9a3a71
-- 151ab3e05a23e9ccd03a6c49830dabb9e9281faf279c31ae40b13e6971dd2fb8
-- 1c926fb3bd99f4a586ed476e4683163892f3958581bf8c24235cd2a415513b7f
-- 1f8dcfaebbcd7e71c2872e0ba2fc6db81d651cf654a21d33c78eae6662e62392
-- f226086b5959eb96bd30dec0ffcbf0f09186cd11721507f416f1c39901addafb
-- 23eff00dde0ee27dabad28c1f4ffb8b09e876f1e1a77c1e6fb735ab517d79b76
-- 586f30907c3849c363145bfdcdabe3e2e4688cbd5688ff968e984b201b474730
-- 8ce219552e235dcaf1c694be122d6339ed4ff8df70bf358cd165e6eb487ccfc5
-- 90fb0cd574155fd8667d20f97ac464eca67bdb6a8ee64184159362d45d79b6a4
-- c2904dc8bbb569536c742fca0c51a766e836d0da8fac1c1abd99744e9b50164f
-- ca932ccaa30955f2fffb1122234fb1524f7de3a8e0044de1ed4fe05cab8702a5
-- f6827dc5af661fbb4bf64bc625c78283ef836c6985bb2bfb836bd0c8d5397332
-- f78cabf7a0e7ed3ef2d1c976c1486281f56a6503354b87219b466f2f7a0b65c4

Table 3 lists MD5 and SHA256 hashes are associated with Maui Ransomware files.

Table 3: File names and hashes of Maui ransomware files
MD5 Hash SHA256 Hash
4118d9adce7350c3eedeb056a3335346 5b7ecf7e9d0715f1122baf4ce745c5fcd769dee48150616753fec4d6da16e99e
9b0e7c460a80f740d455a7521f0eada1 45d8ac1ac692d6bb0fe776620371fca02b60cac8db23c4cc7ab5df262da42b78
fda3a19afa85912f6dc8452675245d6b 56925a1f7d853d814f80e98a1c4890b0a6a84c83a8eded34c585c98b2df6ab19
2d02f5499d35a8dffb4c8bc0b7fec5c2 830207029d83fd46a4a89cd623103ba2321b866428aa04360376e6a390063570
c50b839f2fc3ce5a385b9ae1c05def3a 458d258005f39d72ce47c111a7d17e8c52fe5fc7dd98575771640d9009385456
a452a5f693036320b580d28ee55ae2a3 99b0056b7cc2e305d4ccb0ac0a8a270d3fceb21ef6fc2eb13521a930cea8bd9f
a6e1efd70a077be032f052bb75544358 3b9fe1713f638f85f20ea56fd09d20a96cd6d288732b04b073248b56cdaef878
802e7d6e80d7a60e17f9ffbd62fcbbeb 87bdb1de1dd6b0b75879d8b8aef80b562ec4fad365d7abbc629bcfc1d386afa6
-- 0054147db54544d77a9efd9baf5ec96a80b430e170d6e7c22fcf75261e9a3a71

Table 4 lists MD5 and SHA256 hashes associated with H0lyGh0st Ransomware files.

SHA256 Hash
99fc54786a72f32fd44c7391c2171ca31e72ca52725c68e2dde94d04c286fccd*
F8fc2445a9814ca8cf48a979bff7f182d6538f4d1ff438cf259268e8b4b76f86*
Bea866b327a2dc2aa104b7ad7307008919c06620771ec3715a059e675d9f40af*
6e20b73a6057f8ff75c49e1b7aef08abfcfe4e418e2c1307791036f081335c2d
f4d10b08d7dacd8fe33a6b54a0416eecdaed92c69c933c4a5d3700b8f5100fad
541825cb652606c2ea12fd25a842a8b3456d025841c3a7f563655ef77bb67219
2d978df8df0cf33830aba16c6322198e5889c67d49b40b1cb1eb236bd366826d
414ed95d14964477bebf86dced0306714c497cde14dede67b0c1425ce451d3d7

Df0c7bb88e3c67d849d78d13cee30671b39b300e0cda5550280350775d5762d8

MD5 Hash
a2c2099d503fcc29478205f5aef0283b
9c516e5b95a7e4169ecbd133ed4d205f
d6a7b5db62bf7815a10a17cdf7ddbd4b
c6949a99c60ef29d20ac8a9a3fb58ce5
4b20641c759ed563757cdd95c651ee53
25ee4001eb4e91f7ea0bc5d07f2a9744
18126be163eb7df2194bb902c359ba8e
eaf6896b361121b2c315a35be837576d
e4ee611533a28648a350f2dab85bb72a
e268cb7ab778564e88d757db4152b9fa

* from Microsoft blog post on h0lygh0st

CONTACT INFORMATION

NSA Client Requirements / General Cybersecurity Inquiries:
Defense Industrial Base Inquiries and Cybersecurity Services:
To report incidents and anomalous activity related to information found in this Joint Cybersecurity Advisory, contact CISA’s 24/7 Operations Center at or (888) 282-0870 or your local FBI field office at www.fbi.gov/contact-us/field. When available, please include the following information regarding the incident: date, time, and location of the incident; type of activity; number of people affected; type of equipment used for the activity; the name of the submitting company or organization; and a designated point of contact.

Media Inquiries / Press Desk:

  • NSA Media Relations, 443-634-0721,
  • CISA Media Relations, 703-235-2010,

SUMMARY

Note: This Cybersecurity Advisory (CSA) is part of an ongoing #StopRansomware effort to publish advisories for network defenders that detail various ransomware variants and various ransomware threat actors. These #StopRansomware advisories detail historically and recently 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 about other ransomware threats and no-cost resources.

The United States National Security Agency (NSA), the U.S. Federal Bureau of Investigation (FBI), the U.S. Cybersecurity and Infrastructure Security Agency (CISA), the U.S. Department of Health and Human Services (HHS), the Republic of Korea (ROK) National Intelligence Service (NIS), and the ROK Defense Security Agency (DSA) (hereafter referred to as the “authoring agencies”) are issuing this joint Cybersecurity Advisory (CSA) to highlight ongoing ransomware activity against Healthcare and Public Health Sector organizations and other critical infrastructure sector entities.

This CSA provides an overview of Democratic People’s Republic of Korea (DPRK) state-sponsored ransomware and updates the July 6, 2022, joint CSA North Korean State-Sponsored Cyber Actors Use Maui Ransomware to Target the Healthcare and Public Health Sector. This advisory highlights TTPs and IOCs DPRK cyber actors used to gain access to and conduct ransomware attacks against Healthcare and Public Health (HPH) Sector organizations and other critical infrastructure sector entities, as well as DPRK cyber actors’ use of cryptocurrency to demand ransoms.

The authoring agencies assess that an unspecified amount of revenue from these cryptocurrency operations supports DPRK national-level priorities and objectives, including cyber operations targeting the United States and South Korea governments—specific targets include Department of Defense Information Networks and Defense Industrial Base member networks. The IOCs in this product should be useful to sectors previously targeted by DPRK cyber operations (e.g., U.S. government, Department of Defense, and Defense Industrial Base). The authoring agencies highly discourage paying ransoms as doing so does not guarantee files and records will be recovered and may pose sanctions risks.

For additional information on state-sponsored DPRK malicious cyber activity, see CISA’s North Korea Cyber Threat Overview and Advisories webpage.

Download the PDF version of this report: pdf, 661 kb.

For a downloadable copy of IOCs, see

AA23-040A STIX XML(XML, 196.24 KB )

TECHNICAL DETAILS

Note: This advisory uses the MITRE ATT&CK for Enterprise framework, version 12. See MITRE ATT&CK for Enterprise for all referenced tactics and techniques.

This CSA is supplementary to previous reports on malicious cyber actor activities involving DPRK ransomware campaigns—namely Maui and H0lyGh0st ransomware. The authoring agencies are issuing this advisory to highlight additional observed TTPs DPRK cyber actors are using to conduct ransomware attacks targeting South Korean and U.S. healthcare systems.

Observable TTPs

The TTPs associated with DPRK ransomware attacks include those traditionally observed in ransomware operations. Additionally, these TTPs span phases from acquiring and purchasing infrastructure to concealing DPRK affiliation:

  • Acquire Infrastructure [T1583]. DPRK actors generate domains, personas, and accounts; and identify cryptocurrency services to conduct their ransomware operations. Actors procure infrastructure, IP addresses, and domains with cryptocurrency generated through illicit cybercrime, such as ransomware and cryptocurrency theft.
  • Obfuscate Identity. DPRK actors purposely obfuscate their involvement by operating with or under third-party foreign affiliate identities and use third-party foreign intermediaries to receive ransom payments.
  • Purchase VPNs and VPSs [T1583.003]. DPRK cyber actors will also use virtual private networks (VPNs) and virtual private servers (VPSs) or third-country IP addresses to appear to be from innocuous locations instead of from DPRK.
  • Gain Access [TA0001]. Actors use various exploits of common vulnerabilities and exposures (CVE) to gain access and escalate privileges on networks. Recently observed CVEs that actors used to gain access include remote code execution in the Apache Log4j software library (known as Log4Shell) and remote code execution in unpatched SonicWall SMA 100 appliances [T1190 and T1133]. Observed CVEs used include:
  • CVE 2021-44228
  • CVE-2021-20038
  • CVE-2022-24990

Actors also likely spread malicious code through Trojanized files for “X-Popup,” an open source messenger commonly used by employees of small and medium hospitals in South Korea [T1195].

The actors spread malware by leveraging two domains: xpopup.pe[.]kr and xpopup.com. xpopup.pe[.]kr is registered to IP address 115.68.95[.]128 and xpopup[.]com is registered to IP address 119.205.197[.]111. Related file names and hashes are listed in table 1.

Table 1: Malicious file names and hashes spread by xpopup domains
File NameMD5 Hash
xpopup.rar1f239db751ce9a374eb9f908c74a31c9
X-PopUp.exe6fb13b1b4b42bac05a2ba629f04e3d03
X-PopUp.execf8ba073db7f4023af2b13dd75565f3d
xpopup.exe4e71d52fc39f89204a734b19db1330d3
x-PopUp.exe43d4994635f72852f719abb604c4a8a1
xpopup.exe5ae71e8440bf33b46554ce7a7f3de666
  • Move Laterally and Discovery [TA0007, TA0008]. After initial access, DPRK cyber actors use staged payloads with customized malware to perform reconnaissance activities, upload and download additional files and executables, and execute shell commands [T1083, T1021]. The staged malware is also responsible for collecting victim information and sending it to the remote host controlled by the actors [TA0010].
  • Employ Various Ransomware Tools [TA0040]. Actors have used privately developed ransomware, such as Maui and H0lyGh0st [T1486]. Actors have also been observed using or possessing publically available tools for encryption, such as BitLocker, Deadbolt, ech0raix, GonnaCry, Hidden Tear, Jigsaw, LockBit 2.0, My Little Ransomware, NxRansomware, Ryuk, and YourRansom [T1486]. In some cases, DPRK actors have portrayed themselves as other ransomware groups, such as the REvil ransomware group. For IOCs associated with Maui and H0lyGh0st ransomware usage, please see Appendix B.
  • Demand Ransom in Cryptocurrency. DPRK cyber actors have been observed setting ransoms in bitcoin [T1486].
  • Actors are known to communicate with victims via Proton Mail email accounts. For private companies in the healthcare sector, actors may threaten to expose a company’s proprietary data to competitors if ransoms are not paid. Bitcoin wallet addresses possibly used by DPRK cyber actors include:
    • 1MTHBCrBKYEthfa16zo9kabt4f9jMJz8Rm
    • bc1q80vc4yjgg6umedkut3e9mhehxl4q4dcjjyzh59
    • 1J8spy62o7z2AjQxoUpiCGnBh5cRWKVWJC
    • 16ENLdHbnmDcEV8iqN4vuyZHa7sSdYRh76
    • bc1q3wzxvu8yhs8h7mlkmf7277wyklkah9k4sm9anu
    • bc1q8xyt4jxhw7mgqpwd6qfdjyxgvjeuz57jxrvgk9
    • 1NqihEqYaQaWiZkPVdSMiTbt7dTy1LMxgX
    • bc1qxrpevck3pq1yzrx2pq2rkvkvy0jnm56nzjv6pw
    • 14hVKm7Ft2rxDBFTNkkRC3kGstMGp2A4hk
    • 1KCwfCUgnSy3pzNX7U1i5NwFzRtth4bRBc
    • 16sYqXancDDiijcuruZecCkdBDwDf4vSEC
    • 1N6JphHFaYmYaokS5xH31Z67bvk4ykd9CP
    • LZ1VNJfn6mWjPzkCyoBvqWaBZYXAwn135
    • 1KmWW6LgdgykBBrSXrFu9kdoHz95Fe9kQF
    • 1FX4W9rrG4F3Uc7gJ18GCwGab8XuW8Ajy2
    • bc1qlqgu2l2kms5338zuc95kxavctzyy0v705tpvyc
    • bc1qy6su7vrh7ts5ng2628escmhr98msmzg62ez2sp
    • bc1q8t69gpxsezdcr8w6tfzp3jeptq4tcp2g9d0mwy
    • bc1q9h7yj79sqm4t536q0fdn7n4y2atsvvl22m28ep
    • bc1qj6y72rk039mqpgtcy7mwjd3eum6cx6027ndgmd
    • bc1qcp557vltuu3qc6pk3ld0ayagrxuf2thp3pjzpe
    • bc1ql8wsflrjf9zlusauynzjm83mupq6c9jz9vnqxg
    • bc1qx60ec3nfd5yhsyyxkzkpts54w970yxj84zrdck
    • bc1qunqnjdlvqkjuhtclfp8kzkjpvdz9qnk898xczp
    • bc1q6024d73h48fnhwswhwt3hqz2lzw6x99q0nulm4
    • bc1qwdvexlyvg3mqvqw7g6l09qup0qew80wjj9jh7x
    • bc1qavrtge4p7dmcrnvhlvuhaarx8rek76wxyk7dgg
    • bc1qagaayd57vr25dlqgk7f00nhz9qepqgnlnt4upu
    • bc1quvnaxnpqlzq3mdhfddh35j7e7ufxh3gpc56hca
    • bc1qu0pvfmtxawm8s99lcjvxapungtsmkvwyvak6cs
    • bc1qg3zlxxhhcvt6hkuhmqml8y9pas76cajcu9ltdl
    • bc1qn7a3g23nzpuytchyyteyhkcse84cnylznl3j32
    • bc1qhfmqstxp3yp9muvuz29wk77vjtdyrkff4nrxpu
    • bc1qnh8scrvuqvlzmzgw7eesyrmtes9c5m78duetf3
    • bc1q7qry3lsrphmnw3exs7tkwzpvzjcxs942aq8n0y
    • bc1qcmlcxfsy0zlqhh72jvvc4rh7hvwhx6scp27na0
    • bc1q498fn0gauj2kkjsg35mlwk2cnxhaqlj7hkh8xy
    • bc1qnz4udqkumjghnm2a3zt0w3ep8fwdcyv3krr3jq
    • bc1qk0saaw7p0wrwla6u7tfjlxrutlgrwnudzx9tyw
    • bc1qyue2pgjk09ps7qvfs559k8kee3jkcw4p4vdp57
    • bc1q6qfkt06xmrpclht3acmq00p7zyy0ejydu89zwv
    • bc1qmge6a7sp659exnx78zhm9zgrw88n6un0rl9trs
    • bc1qcywkd7zqlwmjy36c46dpf8cq6ts6wgkjx0u7cn

MITIGATIONS

Note: These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the U.S. National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. For more information on the CPGs, including additional recommended baseline protections, see cisa.gov/cpg.

The authoring agencies urge HPH organizations to:

  • Limit access to data by authenticating and encrypting connections (e.g., using public key infrastructure certificates in virtual private network (VPN) and transport layer security (TLS) connections) with network services, Internet of Things (IoT) medical devices, and the electronic health record system [CPG 3.3].
  • Implement the principle of least privilege by using standard user accounts on internal systems instead of administrative accounts [CPG 1.5], which grant excessive system administration privileges.
  • Turn off weak or unnecessary network device management interfaces, such as Telnet, SSH, Winbox, and HTTP for wide area networks (WANs) and secure with strong passwords and encryption when enabled.
  • Protect stored data by masking the permanent account number (PAN) when displayed and rendering it unreadable when stored—through cryptography, for example.
  • Secure the collection, storage, and processing practices for personally identifiable information (PII)/protected health information (PHI), per regulations such as the Health Insurance Portability and Accountability Act of 1996 (HIPAA). Implementing HIPAA security measures could prevent the introduction of malware to the system [CPG 3.4].
    • Secure PII/ PHI at collection points and encrypt the data at rest and in transit using technologies, such as TLS. Only store personal patient data on internal systems that are protected by firewalls, and ensure extensive backups are available.
    • Create and regularly review internal policies that regulate the collection, storage, access, and monitoring of PII/PHI.
  • Implement and enforce multi-layer network segmentation with the most critical communications and data resting on the most secure and reliable layer [CPG 8.1].
  • Use monitoring tools to observe whether IoT devices are behaving erratically due to a compromise [CPG 3.1].

In addition, the authoring agencies urge all organizations, including HPH Sector organizations, to apply the following recommendations to prepare for and mitigate ransomware incidents:

  • Maintain isolated backups of data, and regularly test backup and restoration [CPG 7.3]. These practices safeguard an organization’s continuity of operations or at least minimize potential downtime from a ransomware incident and protect against data losses.
    • Ensure all backup data is encrypted, immutable (i.e., cannot be altered or deleted), and covers the entire organization’s data infrastructure.
  • Create, maintain, and exercise a basic cyber incident response plan and associated communications plan that includes response procedures for a ransomware incident [CPG 7.1, 7.2].
  • Install updates for operating systems, software, and firmware as soon as they are released [CPG 5.1]. Timely patching is one of the most efficient and cost-effective steps an organization can take to minimize its exposure to cybersecurity threats. Regularly check for software updates and end-of-life notifications and prioritize patching known exploited vulnerabilities. Consider leveraging a centralized patch management system to automate and expedite the process.
  • If you use Remote Desktop Protocol (RDP), or other potentially risky services, secure and monitor them closely [CPG 5.4].
    • Limit access to resources over internal networks, especially by restricting RDP and using virtual desktop infrastructure. After assessing risks, if RDP is deemed operationally necessary, restrict the originating sources, and require phishing-resistant multifactor authentication (MFA) to mitigate credential theft and reuse [CPG 1.3]. If RDP must be available externally, use a VPN, virtual desktop infrastructure, or other means to authenticate and secure the connection before allowing RDP to connect to internal devices. Monitor remote access/RDP logs, enforce account lockouts after a specified number of attempts to block brute force campaigns, log RDP login attempts, and disable unused remote access/RDP ports [CPG 1.1, 3.1].
    • Ensure devices are properly configured and that security features are enabled. Disable ports and protocols not in use for a business purpose (e.g., RDP Transmission Control Protocol port 3389).
    • Restrict the Server Message Block (SMB) protocol within the network to only access necessary servers and remove or disable outdated versions of SMB (i.e., SMB version 1). Threat actors use SMB to propagate malware across organizations.
    • Review the security posture of third-party vendors and those interconnected with your organization. Ensure all connections between third-party vendors and outside software or hardware are monitored and reviewed for suspicious activity [CPG 5.6, 6.2].
    • Implement application control policies that only allow systems to execute known and permitted programs [CPG 2.1].
    • Open document readers in protected viewing modes to help prevent active content from running.
  • Implement a user training program and phishing exercises [CPG 4.3] to raise awareness among users about the risks of visiting websites, clicking on links, and opening attachments. Reinforce the appropriate user response to phishing and spearphishing emails.
  • Require phishing-resistant MFA for as many services as possible [CPG 1.3]—particularly for webmail, VPNs, accounts that access critical systems, and privileged accounts that manage backups.
  • Use strong passwords [CPG 1.4] and avoid reusing passwords for multiple accounts. See CISA Tip Choosing and Protecting Passwords and National Institute of Standards and Technology (NIST) Special Publication 800-63B: Digital Identity Guidelines for more information.
  • Require administrator credentials to install software [CPG 1.5].
  • Audit user accounts with administrative or elevated privileges [CPG 1.5] and configure access controls with least privilege in mind.
  • Install and regularly update antivirus and antimalware software on all hosts.
  • Only use secure networks. Consider installing and using a VPN.
  • Consider adding an email banner to messages coming from outside your organizations [CPG 8.3] indicating that they are higher risk messages.
  • Consider participating in CISA’s no-cost Automated Indicator Sharing (AIS) program to receive real-time exchange of machine-readable cyber threat indicators and defensive measures.

If a ransomware incident occurs at your organization:

  • Follow your organization’s ransomware response checklist.
  • Scan backups. If possible, scan backup data with an antivirus program to check that it is free of malware. This should be performed using an isolated, trusted system to avoid exposing backups to potential compromise.
  • U.S. organizations: Follow the notification requirements as outlined in your cyber incident response plan. Report incidents to appropriate authorities; in the U.S., this would include the FBI at a local FBI Field Office, CISA at cisa.gov/report, or the U.S. Secret Service (USSS) at a USSS Field Office.
  • South Korean organizations: Please report incidents to NIS, KISA (Korea Internet & Security Agency), and KNPA (Korean National Police Agency).
  • Apply incident response best practices found in the joint Cybersecurity Advisory, Technical Approaches to Uncovering and Remediating Malicious Activity, developed by CISA and the cybersecurity authorities of Australia, Canada, New Zealand, and the United Kingdom.

RESOURCES

Stairwell provided a YARA rule to identify Maui ransomware, and a Proof of Concept public RSA key extractor at the following link:
https://www.stairwell.com/news/threat-research-report-maui-ransomware/

REQUEST FOR INFORMATION

The FBI is seeking any information that can be shared, to include boundary logs showing communication to and from foreign IP addresses, bitcoin wallet information, the decryptor file, and/or benign samples of encrypted files. As stated above, the authoring agencies discourage paying ransoms. Payment does not guarantee files will be recovered and may embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. However, the agencies understand that when victims are faced with an inability to function, all options are evaluated to protect shareholders, employees, and customers.

Regardless of whether you or your organization decide to pay a ransom, the authoring agencies urge you to promptly report ransomware incidents using the contact information above.

ACKNOWLEDGEMENTS

NSA, FBI, CISA, and HHS would like to thank ROK NIS and DSA for their contributions to this CSA.

Disclaimer of endorsement

The information and opinions contained in this document are provided "as is" and without any warranties or guarantees. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the United States Government, and this guidance shall not be used for advertising or product endorsement purposes.

Trademark recognition

Microsoft Threat Intelligence Center is a registered trademark of Microsoft Corporation. Apache®, Sonicwall, and Apache Log4j are trademarks of Apache Software Foundation. TerraMaster Operating System is a registered trademark of Octagon Systems.

Purpose

This document was developed in furtherance of the authors’ cybersecurity missions, including their responsibilities to identify and disseminate threats, and to develop and issue cybersecurity specifications and mitigations. This information may be shared broadly to reach all appropriate stakeholders.

Appendix A: CVE Details
CVE-2021-44228     CVSS 3.0: 10 (Critical)
Vulnerability Description
Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.
Recommended Mitigations
Apply patches provided by vendor and perform required system updates.
Detection Methods
See vendors’ Guidance For Preventing, Detecting, and Hunting for Exploitation of the Log4j 2 Vulnerability.
Vulnerable Technologies and Versions
There are numerous vulnerable technologies and versions associated with CVE-2021-44228. For a full list, please check https://nvd.nist.gov/vuln/detail/CVE-2021-44228.
See https://nvd.nist.gov/vuln/detail/CVE-2021-44228 for more information.
CVE-2021-20038     CVSS 3.0: 9.8 (Critical)
Vulnerability Description
A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote unauthenticated attacker to potentially execute code as a 'nobody' user in the appliance. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.
Recommended Mitigations
Apply all appropriate vendor updates
Upgrade to:
  • SMA 100 Series - (SMA 200, 210, 400, 410, 500v (ESX, Hyper-V, KVM, AWS, Azure):
  • SonicWall SMA100 build versions 10.2.0.9-41sv or later
  • SonicWall SMA100 build versions 10.2.1.3-27sv or later

System administrators should refer to the SonicWall Security Advisories in the reference section to determine affected applications/systems and appropriate fix actions.

Support for 9.0.0 firmware ended on 10/31/2021. Customers still using that firmware are requested to upgrade to the latest 10.2.x versions.

Vulnerable Technologies and Versions
Sonicwall Sma 200 Firmware 10.2.0.8-37Sv
Sonicwall Sma 200 Firmware 10.2.1.1-19Sv
Sonicwall Sma 200 Firmware 10.2.1.2-24Sv
Sonicwall Sma 210 Firmware 10.2.0.8-37Sv
Sonicwall Sma 210 Firmware 10.2.1.1-19Sv
Sonicwall Sma 210 Firmware 10.2.1.2-24Sv
Sonicwall Sma 410 Firmware 10.2.0.8-37Sv
Sonicwall Sma 410 Firmware 10.2.1.1-19Sv
Sonicwall Sma 410 Firmware 10.2.1.2-24Sv
Sonicwall Sma 400 Firmware 10.2.0.8-37Sv
Sonicwall Sma 400 Firmware 10.2.1.1-19Sv
Sonicwall Sma 400 Firmware 10.2.1.2-24Sv
Sonicwall Sma 500V Firmware 10.2.0.8-37Sv
Sonicwall Sma 500V Firmware 10.2.1.1-19Sv
Sonicwall Sma 500V Firmware 10.2.1.2-24Sv
See https://nvd.nist.gov/vuln/detail/CVE-2021-20038 for more information.
CVE-2022-24990    CVSS 3.x: N/A
Vulnerability Description
The TerraMaster OS Unauthenticated Remote Command Execution via PHP Object Instantiation Vulnerability is characterized by scanning activity targeting a flaw in the script enabling a remote adversary to execute commands on the target endpoint. The vulnerability is created by improper input validation of the webNasIPS component in the api.php script and resides on the TNAS device appliances' operating system where users manage storage, backup data, and configure applications. By exploiting the script flaw a remote unauthenticated attacker can pass specially crafted data to the application and execute arbitrary commands on the target system. This may result in complete compromise of the target system, including the exfiltration of information. TNAS devices can be chained to acquire unauthenticated remote code execution with highest privileges.
Recommended Mitigations
Install relevant vendor patches. This vulnerability was patched in TOS version 4.2.30
Vulnerable Technologies and Versions
TOS v 4.2.29
See https://octagon.net/blog/2022/03/07/cve-2022-24990-terrmaster-tos-unauthenticated-remote-command-execution-via-php-object-instantiation/ and https://forum.terra-master.com/en/viewtopic.php?t=3030 for more information.
Appendix B: Indicators of Compromise (IOCs)

The IOC section includes hashes and IP addresses for the Maui and H0lyGh0st ransomware variants—as well as custom malware implants assumedly developed by DPRK cyber actors, such as remote access trojans (RATs), loaders, and other tools—that enable subsequent deployment of ransomware. For additional Maui IOCs, see joint CSA North Korean State-Sponsored Cyber Actors Use Maui Ransomware to Target the Healthcare and Public Health Sector.

Table 2 lists MD5 and SHA256 hashes associated with malware implants, RATs, and other tools used by DPRK cyber actors, including tools that drop Maui ransomware files.

Table 2: File names and hashes of malicious implants, RATs, and tools
MD5HashSHA256Hash
079b4588eaa99a1e802adf5e0b26d8aaf67ee77d6129bd1bcd5d856c0fc5314169b946d32b8abaa4e680bb98130b38e7
0e9e256d8173854a7bc26982b1dde783--
12c15a477e1a96120c09a860c9d479b36263e421e397db821669420489d2d3084f408671524fd4e1e23165a16dda2225
131fc4375971af391b459de33f81c253--
17c46ed7b80c2e4dbea6d0e88ea0827cb9af4660da00c7fa975910d0a19fda072031c15fad1eef935a609842c51b7f7d
1875f6a68f70bee316c8a6eda9ebf8de672ec8899b8ee513dbfc4590440a61023846ddc2ca94c88ae637144305c497e7
1a74c8d8b74ca2411c1d3d22373a6769ba8f9e7afe5f78494c111971c39a89111ef9262bf23e8a764c6f65c818837a44
1f6d9f8fbdbbd4e6ed8cd73b9e95a9284f089afa51fd0c1b2a39cc11cedb3a4a326111837a5408379384be6fe846e016
2d02f5499d35a8dffb4c8bc0b7fec5c2830207029d83fd46a4a89cd623103ba2321b866428aa04360376e6a390063570
2e18350194e59bc6a2a3f6d59da11bd8655aa64860f1655081489cf85b77f72a49de846a99dd122093db4018434b83ae
3bd22e0ac965ebb6a18bb71ba39e96dc6b7f566889b80d1dba4f92d5e2fb2f5ef24f57fcfd56bb594978dffe9edbb9eb
40f21743f9cb927b2c84ecdb7dfb14a65081f54761947bc9ce4aa2a259a0bd60b4ec03d32605f8e3635c4d4edaf48894
4118d9adce7350c3eedeb056a33353465b7ecf7e9d0715f1122baf4ce745c5fcd769dee48150616753fec4d6da16e99e
43e756d80225bdf1200bc34eef5adca8afb2d4d88f59e528f0e388705113ae54b7b97db4f03a35ae43cc386a48f263a0
47791bf9e017e3001ddc68a7351ca2d6863b707873f7d653911e46885e261380b410bb3bf6b158daefb47562e93cb657
505262547f8879249794fc31eea41fc6f32f6b229913d68daad937cc72a57aa45291a9d623109ed48938815aa7b6005c
5130888a0ad3d64ad33c65de696d3fa2c92c1f3e77a1876086ce530e87aa9c1f9cbc5e93c5e755b29cad10a2f3991435
58ad3103295afcc22bde8d81e77c282f18b75949e03f8dcad513426f1f9f3ca209d779c24cd4e941d935633b1bec00cb
5be1e382cd9730fbe386b69bd8045ee75ad106e333de056eac78403b033b89c58b4c4bdda12e2f774625d47ccfd3d3ae
5c6f9c83426c6d33ff2d4e72c039b747a3b7e88d998078cfd8cdf37fa5454c45f6cbd65f4595fb94b2e9c85fe767ad47
640e70b0230dc026eff922fb1e44c2ea6319102bac226dfc117c3c9e620cd99c7eafbf3874832f2ce085850aa042f19c
67f4dad1a94ed8a47283c2c0c05a75943fe624c33790b409421f4fa2bb8abfd701df2231a959493c33187ed34bec0ae7
70652edadedbacfd30d33a826853467d196fb1b6eff4e7a049cea323459cfd6c0e3900d8d69e1d80bffbaabd24c06eba
739812e2ae1327a94e441719b885bd196122c94cbfa11311bea7129ecd5aea6fae6c51d23228f7378b5f6b2398728f67
76c3d2092737d964dfd627f1ced0af80bffe910904efd1f69544daa9b72f2a70fb29f73c51070bde4ea563de862ce4b1
802e7d6e80d7a60e17f9ffbd62fcbbeb87bdb1de1dd6b0b75879d8b8aef80b562ec4fad365d7abbc629bcfc1d386afa6
827103a6b6185191fd5618b7e82da292--
830bc975a04ab0f62bfedf27f7aca673--
85995257ac07ae5a6b4a86758a2283d7--
85f6e3e3f0bdd0c1b3084fc86ee59d19f1576627e8130e6d5fde0dbe3dffcc8bc9eef1203d15fcf09cd877ced1ccc72a
87a6bda486554ab16c82bdfb12452e8b980bb08ef3e8afcb8c0c1a879ec11c41b29fd30ac65436495e69de79c555b2be
891db50188a90ddacfaf7567d2d0355d0837dd54268c373069fc5c1628c6e3d75eb99c3b3efc94c45b73e2cf9a6f3207
894de380a249e677be2acb8fbdfba2ef--
8b395cc6ecdec0900facf6e93ec48fbb--
92a6c017830cda80133bf97eb77d3292d1aba3f95f11fc6e5fec7694d188919555b7ff097500e811ff4a5319f8f230be
9b0e7c460a80f740d455a7521f0eada145d8ac1ac692d6bb0fe776620371fca02b60cac8db23c4cc7ab5df262da42b78
9b9d4cb1f681f19417e541178d8c75d7f5f6e538001803b0aa008422caf2c3c2a79b2eeee9ddc7feda710e4aba96fea4
a1f9e9f5061313325a275d448d4ddd59dfdd72c9ce1212f9d9455e2bca5a327c88d2d424ea5c086725897c83afc3d42d
a452a5f693036320b580d28ee55ae2a399b0056b7cc2e305d4ccb0ac0a8a270d3fceb21ef6fc2eb13521a930cea8bd9f
a6e1efd70a077be032f052bb755443583b9fe1713f638f85f20ea56fd09d20a96cd6d288732b04b073248b56cdaef878
ad4eababfe125110299e5a24be84472ea557a0c67b5baa7cf64bd4d42103d3b2852f67acf96b4c5f14992c1289b55eaa
b1c1d28dc7da1d58abab73fa98f60a8338491f48d0cbaab7305b5ddca64ba41a2beb89d81d5fb920e67d0c7334c89131
b6f91a965b8404d1a276e43e61319931--
bdece9758bf34fcad9cba1394519019b9d6de05f9a3e62044ad9ae66111308ccb9ed2ee46a3ea37d85afa92e314e7127
c3850f4cc12717c2b54753f8ca5d5e0e99b448e91669b92c2cc3417a4d9711209509274dab5d7582baacfab5028a818c
c50b839f2fc3ce5a385b9ae1c05def3a458d258005f39d72ce47c111a7d17e8c52fe5fc7dd98575771640d9009385456
cf236bf5b41d26967b1ce04ebbdb404160425a4d5ee04c8ae09bfe28ca33bf9e76a43f69548b2704956d0875a0f25145
d0e203e8845bf282475a8f816340f2e8f6375c5276d1178a2a0fe1a16c5668ce523e2f846c073bf75bb2558fdec06531
ddb1f970371fa32faae61fc5b8423d4bdda53eee2c5cb0abdbf5242f5e82f4de83898b6a9dd8aa935c2be29bafc9a469
f2f787868a3064407d79173ac5fc086492adc5ea29491d9245876ba0b2957393633c9998eb47b3ae1344c13a44cd59ae
fda3a19afa85912f6dc8452675245d6b56925a1f7d853d814f80e98a1c4890b0a6a84c83a8eded34c585c98b2df6ab19
--0054147db54544d77a9efd9baf5ec96a80b430e170d6e7c22fcf75261e9a3a71
--151ab3e05a23e9ccd03a6c49830dabb9e9281faf279c31ae40b13e6971dd2fb8
--1c926fb3bd99f4a586ed476e4683163892f3958581bf8c24235cd2a415513b7f
--1f8dcfaebbcd7e71c2872e0ba2fc6db81d651cf654a21d33c78eae6662e62392
--f226086b5959eb96bd30dec0ffcbf0f09186cd11721507f416f1c39901addafb
--23eff00dde0ee27dabad28c1f4ffb8b09e876f1e1a77c1e6fb735ab517d79b76
--586f30907c3849c363145bfdcdabe3e2e4688cbd5688ff968e984b201b474730
--8ce219552e235dcaf1c694be122d6339ed4ff8df70bf358cd165e6eb487ccfc5
--90fb0cd574155fd8667d20f97ac464eca67bdb6a8ee64184159362d45d79b6a4
--c2904dc8bbb569536c742fca0c51a766e836d0da8fac1c1abd99744e9b50164f
--ca932ccaa30955f2fffb1122234fb1524f7de3a8e0044de1ed4fe05cab8702a5
--f6827dc5af661fbb4bf64bc625c78283ef836c6985bb2bfb836bd0c8d5397332
--f78cabf7a0e7ed3ef2d1c976c1486281f56a6503354b87219b466f2f7a0b65c4

Table 3 lists MD5 and SHA256 hashes are associated with Maui Ransomware files.

Table 3: File names and hashes of Maui ransomware files
MD5 HashSHA256 Hash
4118d9adce7350c3eedeb056a33353465b7ecf7e9d0715f1122baf4ce745c5fcd769dee48150616753fec4d6da16e99e
9b0e7c460a80f740d455a7521f0eada145d8ac1ac692d6bb0fe776620371fca02b60cac8db23c4cc7ab5df262da42b78
fda3a19afa85912f6dc8452675245d6b56925a1f7d853d814f80e98a1c4890b0a6a84c83a8eded34c585c98b2df6ab19
2d02f5499d35a8dffb4c8bc0b7fec5c2830207029d83fd46a4a89cd623103ba2321b866428aa04360376e6a390063570
c50b839f2fc3ce5a385b9ae1c05def3a458d258005f39d72ce47c111a7d17e8c52fe5fc7dd98575771640d9009385456
a452a5f693036320b580d28ee55ae2a399b0056b7cc2e305d4ccb0ac0a8a270d3fceb21ef6fc2eb13521a930cea8bd9f
a6e1efd70a077be032f052bb755443583b9fe1713f638f85f20ea56fd09d20a96cd6d288732b04b073248b56cdaef878
802e7d6e80d7a60e17f9ffbd62fcbbeb87bdb1de1dd6b0b75879d8b8aef80b562ec4fad365d7abbc629bcfc1d386afa6
--0054147db54544d77a9efd9baf5ec96a80b430e170d6e7c22fcf75261e9a3a71

Table 4 lists MD5 and SHA256 hashes associated with H0lyGh0st Ransomware files.

SHA256 Hash
99fc54786a72f32fd44c7391c2171ca31e72ca52725c68e2dde94d04c286fccd*
F8fc2445a9814ca8cf48a979bff7f182d6538f4d1ff438cf259268e8b4b76f86*
Bea866b327a2dc2aa104b7ad7307008919c06620771ec3715a059e675d9f40af*
6e20b73a6057f8ff75c49e1b7aef08abfcfe4e418e2c1307791036f081335c2d
f4d10b08d7dacd8fe33a6b54a0416eecdaed92c69c933c4a5d3700b8f5100fad
541825cb652606c2ea12fd25a842a8b3456d025841c3a7f563655ef77bb67219
2d978df8df0cf33830aba16c6322198e5889c67d49b40b1cb1eb236bd366826d
414ed95d14964477bebf86dced0306714c497cde14dede67b0c1425ce451d3d7

Df0c7bb88e3c67d849d78d13cee30671b39b300e0cda5550280350775d5762d8

MD5 Hash
a2c2099d503fcc29478205f5aef0283b
9c516e5b95a7e4169ecbd133ed4d205f
d6a7b5db62bf7815a10a17cdf7ddbd4b
c6949a99c60ef29d20ac8a9a3fb58ce5
4b20641c759ed563757cdd95c651ee53
25ee4001eb4e91f7ea0bc5d07f2a9744
18126be163eb7df2194bb902c359ba8e
eaf6896b361121b2c315a35be837576d
e4ee611533a28648a350f2dab85bb72a
e268cb7ab778564e88d757db4152b9fa

* from Microsoft blog post on h0lygh0st

CONTACT INFORMATION

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