Original release date: October 4, 2022

Summary

Actions to Help Protect Against Russian State-Sponsored Malicious Cyber Activity:

• Enforce multifactor authentication (MFA) on all user accounts.
• Implement network segmentation to separate network segments based on role and functionality.
• Update software, including operating systems, applications, and firmware, on network assets.
• Audit account usage.

From November 2021 through January 2022, the Cybersecurity and Infrastructure Security Agency (CISA) responded to advanced persistent threat (APT) activity on a Defense Industrial Base (DIB) Sector organization’s enterprise network. During incident response activities, CISA uncovered that likely multiple APT groups compromised the organization’s network, and some APT actors had long-term access to the environment. APT actors used an open-source toolkit called Impacket to gain their foothold within the environment and further compromise the network, and also used a custom data exfiltration tool, CovalentStealer, to steal the victim’s sensitive data.

This joint Cybersecurity Advisory (CSA) provides APT actors tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) identified during the incident response activities by CISA and a third-party incident response organization. The CSA includes detection and mitigation actions to help organizations detect and prevent related APT activity. CISA, the Federal Bureau of Investigation (FBI), and the National Security Agency (NSA) recommend DIB sector and other critical infrastructure organizations implement the mitigations in this CSA to ensure they are managing and reducing the impact of cyber threats to their networks.

Download the PDF version of this report: pdf, 692 KB

For a downloadable copy of IOCs, see the following files:

• Malware Analysis Report (MAR)-10365227-1.stix, 966 kb
• MAR-10365227-2.stix, 249B
• MAR-10365227-3.stix, 3.2 MB

Technical Details

Threat Actor Activity

Note: This advisory uses the MITRE ATT&CK® for Enterprise framework, version 11. See the MITRE ATT&CK Tactics and Techniques section for a table of the APT cyber activity mapped to MITRE ATT&CK for Enterprise framework.

From November 2021 through January 2022, CISA conducted an incident response engagement on a DIB Sector organization’s enterprise network. The victim organization also engaged a third-party incident response organization for assistance. During incident response activities, CISA and the trusted –third-party identified APT activity on the victim’s network.

Some APT actors gained initial access to the organization’s Microsoft Exchange Server as early as mid-January 2021. The initial access vector is unknown. Based on log analysis, the actors gathered information about the exchange environment and performed mailbox searches within a four-hour period after gaining access. In the same period, these actors used a compromised administrator account (“Admin 1”) to access the EWS Application Programming Interface (API). In early February 2021, the actors returned to the network and used Admin 1 to access EWS API again. In both instances, the actors used a virtual private network (VPN).

Four days later, the APT actors used Windows Command Shell over a three-day period to interact with the victim’s network. The actors used Command Shell to learn about the organization’s environment and to collect sensitive data, including sensitive contract-related information from shared drives, for eventual exfiltration. The actors manually collected files using the command-line tool, WinRAR. These files were split into approximately 3MB chunks located on the Microsoft Exchange server within the CU2hedebug directory. See Appendix: Windows Command Shell Activity for additional information, including specific commands used.

During the same period, APT actors implanted Impacket, a Python toolkit for programmatically constructing and manipulating network protocols, on another system. The actors used Impacket to attempt to move laterally to another system.

In early March 2021, APT actors exploited CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065 to install 17 China Chopper webshells on the Exchange Server. Later in March, APT actors installed HyperBro on the Exchange Server and two other systems. For more information on the HyperBro and webshell samples, see CISA MAR-10365227-2 and -3.

In April 2021, APT actors used Impacket for network exploitation activities. See the Use of Impacket section for additional information. From late July through mid-October 2021, APT actors employed a custom exfiltration tool, CovalentStealer, to exfiltrate the remaining sensitive files. See the Use of Custom Exfiltration Tool: CovalentStealer section for additional information.

APT actors maintained access through mid-January 2022, likely by relying on legitimate credentials.

Use of Impacket

CISA discovered activity indicating the use of two Impacket tools: wmiexec.py and smbexec.py. These tools use Windows Management Instrumentation (WMI) and Server Message Block (SMB) protocol, respectively, for creating a semi-interactive shell with the target device. Through the Command Shell, an Impacket user with credentials can run commands on the remote device using the Windows management protocols required to support an enterprise network.

The APT cyber actors used existing, compromised credentials with Impacket to access a higher privileged service account used by the organization’s multifunctional devices. The threat actors first used the service account to remotely access the organization’s Microsoft Exchange server via Outlook Web Access (OWA) from multiple external IP addresses; shortly afterwards, the actors assigned the Application Impersonation role to the service account by running the following PowerShell command for managing Exchange:

This command gave the service account the ability to access other users’ mailboxes.

The APT cyber actors used virtual private network (VPN) and virtual private server (VPS) providers, M247 and SurfShark, as part of their techniques to remotely access the Microsoft Exchange server. Use of these hosting providers, which serves to conceal interaction with victim networks, are common for these threat actors. According to CISA’s analysis of the victim’s Microsoft Exchange server Internet Information Services (IIS) logs, the actors used the account of a former employee to access the EWS. EWS enables access to mailbox items such as email messages, meetings, and contacts. The source IP address for these connections is mostly from the VPS hosting provider, M247.

Use of Custom Exfiltration Tool: CovalentStealer

The threat actors employed a custom exfiltration tool, CovalentStealer, to exfiltrate sensitive files.

CovalentStealer is designed to identify file shares on a system, categorize the files, and upload the files to a remote server. CovalentStealer includes two configurations that specifically target the victim’s documents using predetermined files paths and user credentials. CovalentStealer stores the collected files on a Microsoft OneDrive cloud folder, includes a configuration file to specify the types of files to collect at specified times and uses a 256-bit AES key for encryption. See CISA MAR-10365227-1 for additional technical details, including IOCs and detection signatures.

MITRE ATT&CK Tactics and Techniques

MITRE ATT&CK is a globally accessible knowledge base of adversary tactics and techniques based on real-world observations. CISA uses the ATT&CK Framework as a foundation for the development of specific threat models and methodologies. Table 1 lists the ATT&CK techniques employed by the APT actors.

DETECTION

Given the actors’ demonstrated capability to maintain persistent, long-term access in compromised enterprise environments, CISA, FBI, and NSA encourage organizations to:

• Monitor logs for connections from unusual VPSs and VPNs. Examine connection logs for access from unexpected ranges, particularly from machines hosted by SurfShark and M247.
• Monitor for suspicious account use (e.g., inappropriate or unauthorized use of administrator accounts, service accounts, or third-party accounts). To detect use of compromised credentials in combination with a VPS, follow the steps below:
  • Review logs for « impossible logins, » such as logins with changing username, user agent strings, and IP address combinations or logins where IP addresses do not align to the expected user’s geographic location.
  • Search for « impossible travel, » which occurs when a user logs in from multiple IP addresses that are a significant geographic distance apart (i.e., a person could not realistically travel between the geographic locations of the two IP addresses in the time between logins). Note: This detection opportunity can result in false positives if legitimate users apply VPN solutions before connecting to networks.
  • Search for one IP used across multiple accounts, excluding expected logins.
    • Take note of any M247-associated IP addresses used along with VPN providers (e.g., SurfShark). Look for successful remote logins (e.g., VPN, OWA) for IPs coming from M247- or using SurfShark-registered IP addresses.
  • Identify suspicious privileged account use after resetting passwords or applying user account mitigations.
  • Search for unusual activity in typically dormant accounts.
  • Search for unusual user agent strings, such as strings not typically associated with normal user activity, which may indicate bot activity.
• Review the YARA rules provided in MAR-10365227-1 to assist in determining whether malicious activity has been observed.
• Monitor for the installation of unauthorized software, including Remote Server Administration Tools (e.g., psexec, RdClient, VNC, and ScreenConnect).
• Monitor for anomalous and known malicious command-line use. See Appendix: Windows Command Shell Activity for commands used by the actors to interact with the victim’s environment.
• Monitor for unauthorized changes to user accounts (e.g., creation, permission changes, and enabling a previously disabled account).

CONTAINMENT AND REMEDIATION

Organizations affected by active or recently active threat actors in their environment can take the following initial steps to aid in eviction efforts and prevent re-entry:

• Report the incident. Report the incident to U.S. Government authorities and follow your organization’s incident response plan.
  • Report incidents to CISA via CISA’s 24/7 Operations Center (report@cisa.gov or 888-282-0870).
  • Report incidents to your local FBI field office at fbi.gov/contact-us/field-offices or to FBI’s 24/7 Cyber Watch (CyWatch) via (855) 292-3937 or CyWatch@fbi.gov.
  • For DIB incident reporting, contact the Defense Cyber Crime Center (DC3) via DIBNET at dibnet.dod.mil/portal/intranet or (410) 981 0104.
• Reset all login accounts. Reset all accounts used for authentication since it is possible that the threat actors have additional stolen credentials. Password resets should also include accounts outside of Microsoft Active Directory, such as network infrastructure devices and other non-domain joined devices (e.g., IoT devices).
• Monitor SIEM logs and build detections. Create signatures based on the threat actor TTPs and use these signatures to monitor security logs for any signs of threat actor re-entry.
• Enforce MFA on all user accounts. Enforce phishing-resistant MFA on all accounts without exception to the greatest extent possible.
• Follow Microsoft’s security guidance for Active Directory—Best Practices for Securing Active Directory.
• Audit accounts and permissions. Audit all accounts to ensure all unused accounts are disabled or removed and active accounts do not have excessive privileges. Monitor SIEM logs for any changes to accounts, such as permission changes or enabling a previously disabled account, as this might indicate a threat actor using these accounts.
• Harden and monitor PowerShell by reviewing guidance in the joint Cybersecurity Information Sheet—Keeping PowerShell: Security Measures to Use and Embrace.

Mitigations

Mitigation recommendations are usually longer-term efforts that take place before a compromise as part of risk management efforts, or after the threat actors have been evicted from the environment and the immediate response actions are complete. While some may be tailored to the TTPs used by the threat actor, recovery recommendations are largely general best practices and industry standards aimed at bolstering overall cybersecurity posture.

Segment Networks Based on Function

• Implement network segmentation to separate network segments based on role and functionality. Proper network segmentation significantly reduces the ability for ransomware and other threat actor lateral movement by controlling traffic flows between—and access to—various subnetworks. (See CISA’s Infographic on Layering Network Security Through Segmentation and NSA’s Segment Networks and Deploy Application-Aware Defenses.)
• Isolate similar systems and implement micro-segmentation with granular access and policy restrictions to modernize cybersecurity and adopt Zero Trust (ZT) principles for both network perimeter and internal devices. Logical and physical segmentation are critical to limiting and preventing lateral movement, privilege escalation, and exfiltration.

Manage Vulnerabilities and Configurations

• Update software, including operating systems, applications, and firmware, on network assets. Prioritize patching known exploited vulnerabilities and critical and high vulnerabilities that allow for remote code execution or denial-of-service on internet-facing equipment.
• Implement a configuration change control process that securely creates device configuration backups to detect unauthorized modifications. When a configuration change is needed, document the change, and include the authorization, purpose, and mission justification. Periodically verify that modifications have not been applied by comparing current device configurations with the most recent backups. If suspicious changes are observed, verify the change was authorized.

Search for Anomalous Behavior

• Use cybersecurity visibility and analytics tools to improve detection of anomalous behavior and enable dynamic changes to policy and other response actions. Visibility tools include network monitoring tools and host-based logs and monitoring tools, such as an endpoint detection and response (EDR) tool. EDR tools are particularly useful for detecting lateral connections as they have insight into common and uncommon network connections for each host.
• Monitor the use of scripting languages (e.g., Python, Powershell) by authorized and unauthorized users. Anomalous use by either group may be indicative of malicious activity, intentional or otherwise.

Restrict and Secure Use of Remote Admin Tools

• Limit the number of remote access tools as well as who and what can be accessed using them. Reducing the number of remote admin tools and their allowed access will increase visibility of unauthorized use of these tools.
• Use encrypted services to protect network communications and disable all clear text administration services(e.g., Telnet, HTTP, FTP, SNMP 1/2c). This ensures that sensitive information cannot be easily obtained by a threat actor capturing network traffic.

Implement a Mandatory Access Control Model

• Implement stringent access controls to sensitive data and resources. Access should be restricted to those users who require access and to the minimal level of access needed.

Audit Account Usage

• Monitor VPN logins to look for suspicious access (e.g., logins from unusual geo locations, remote logins from accounts not normally used for remote access, concurrent logins for the same account from different locations, unusual times of the day).
• Closely monitor the use of administrative accounts. Admin accounts should be used sparingly and only when necessary, such as installing new software or patches. Any use of admin accounts should be reviewed to determine if the activity is legitimate.
• Ensure standard user accounts do not have elevated privileges Any attempt to increase permissions on standard user accounts should be investigated as a potential compromise.

VALIDATE SECURITY CONTROLS

In addition to applying mitigations, CISA, FBI, and NSA recommend exercising, testing, and validating your organization’s security program against threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. CISA, FBI, and NSA recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Table 1).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze the performance of your detection and prevention technologies.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

CISA, FBI, and NSA recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

RESOURCES

CISA offers several no-cost scanning and testing services to help organizations reduce their exposure to threats by taking a proactive approach to mitigating attack vectors. See cisa.gov/cyber-hygiene-services.

U.S. DIB sector organizations may consider signing up for the NSA Cybersecurity Collaboration Center’s DIB Cybersecurity Service Offerings, including Protective Domain Name System (PDNS) services, vulnerability scanning, and threat intelligence collaboration for eligible organizations. For more information on how to enroll in these services, email dib_defense@cyber.nsa.gov.

ACKNOWLEDGEMENTS

CISA, FBI, and NSA acknowledge Mandiant for its contributions to this CSA.

APPENDIX: WINDOWS COMMAND SHELL ACTIVITY

Over a three-day period in February 2021, APT cyber actors used Windows Command Shell to interact with the victim’s environment. When interacting with the victim’s system and executing commands, the threat actors used /q and /c parameters to turn the echo off, carry out the command specified by a string, and stop its execution once completed.

On the first day, the threat actors consecutively executed many commands within the Windows Command Shell to learn about the organization’s environment and to collect sensitive data for eventual exfiltration (see Table 2).

On the second day, the APT cyber actors executed the commands in Table 3 to perform discovery as well as collect and archive data.

On the third day, the APT cyber actors returned to the organization’s network and executed the commands in Table 4.

References

• [1] Microsoft Net Share
• [2] Microsoft Get-ChildItem
• [3] Microsoft systeminfo
• [4] Microsoft tasklist
• [5] Microsoft ipconfig
• [6] Microsoft Route
• [7] Microsoft netstat
• [8] Microsoft certutil
• [9] Microsoft ping
• [10] Microsoft taskkill
• [11] Microsoft Compress-Archive
• [12] NTFSInfo v1.2
• [13] rarlab
• [14] Microsoft Import-Module
• [15] Microsoft set (environment variable)
• [16] Microsoft tasklist
• [17] Mitre ATT&CK – Sofware: TaskList
• [18] Microsoft find
• [19] Microsoft ping
• [20] Microsoft del

Revisions

• October 4, 2022: Initial version

Source de l’article sur us-cert.gov

Original release date: September 22, 2022

Summary

Traditional approaches to securing OT/ICS do not adequately address current threats.

Operational technology/industrial control system (OT/ICS) assets that operate, control, and monitor day-to-day critical infrastructure and industrial processes continue to be an attractive target for malicious cyber actors. These cyber actors, including advanced persistent threat (APT) groups, target OT/ICS assets to achieve political gains, economic advantages, or destructive effects. Because OT/ICS systems manage physical operational processes, cyber actors’ operations could result in physical consequences, including loss of life, property damage, and disruption of National Critical Functions.

OT/ICS devices and designs are publicly available, often incorporate vulnerable information technology (IT) components, and include external connections and remote access that increase their attack surfaces. In addition, a multitude of tools are readily available to exploit IT and OT systems. As a result of these factors, malicious cyber actors present an increasing risk to ICS networks.

Traditional approaches to securing OT/ICS do not adequately address current threats to those systems. However, owners and operators who understand cyber actors’ tactics, techniques, and procedures (TTPs) can use that knowledge when prioritizing hardening actions for OT/ICS.

This joint Cybersecurity Advisory, which builds on previous NSA and CISA guidance to stop malicious ICS activity and reduce OT exposure [1] [2], describes TTPs that malicious actors use to compromise OT/ICS assets. It also recommends mitigations that owners and operators can use to defend their systems. NSA and CISA encourage OT/ICS owners and operators to apply the recommendations in this CSA.

Download the PDF version of this report: pdf, 538.12 kb

Technical Details

OT/ICS assets operate, control, and monitor industrial processes throughout U.S. critical infrastructure. Traditional ICS assets are difficult to secure due to their design for maximum availability and safety, coupled with their use of decades-old systems that often lack any recent security updates. Newer ICS assets may be able to be configured more securely, but often have an increased attack surface due to incorporating Internet or IT network connectivity to facilitate remote control and operations. The net effect of the convergence of IT and OT platforms has increased the risk of cyber exploitation of control systems. [3]

Today’s cyber realm is filled with well-funded malicious cyber actors financed by nation-states, as well as less sophisticated groups, independent hackers, and insider threats. Control systems have been targeted by a variety of these malicious cyber actors in recent years to achieve political gains, economic advantages, and possibly destructive effects. [4] [5] [6] [7] [8] More recently, APT actors have also developed tools for scanning, compromising, and controlling targeted OT devices. [9] 

Malicious actors’ game plan for control system intrusions

Cyber actors typically follow these steps to plan and execute compromises against critical infrastructure control systems:

1. Establish intended effect and select a target.
2. Collect intelligence about the target system.
3. Develop techniques and tools to navigate and manipulate the system.
4. Gain initial access to the system.
5. Execute techniques and tools to create the intended effect.

Leveraging specific expertise and network knowledge, malicious actors such as nation-state actors can conduct these steps in a coordinated manner, sometimes concurrently and repeatedly, as illustrated by real world cyber activity. [5] [10]

Establish intended effect and select a target

Cyber actors, from cyber criminals to state-sponsored APT actors, target critical infrastructure to achieve a variety of objectives. Cyber criminals are financially motivated and target OT/ICS assets for financial gain (e.g., data extortion or ransomware operations). State-sponsored APT actors target critical infrastructure for political and/or military objectives, such as destabilizing political or economic landscapes or causing psychological or social impacts on a population. The cyber actor selects the target and the intended effect—to disrupt, disable, deny, deceive, and/or destroy—based on these objectives. For example, disabling power grids in strategic locations could destabilize economic landscapes or support broader military campaigns. Disrupting water treatment facilities or threatening to destroy a dam could have psychological or social impacts on a population. [11] [12]

Collect intelligence about the target system

Once the intent and target are established, the actor collects intelligence on the targeted control system. The actor may collect data from multiple sources, including:

• Open-source research: A great deal of information about control systems and their designs is publicly available. For example, solicitation information and employment advertisements may indicate components and—list specific model numbers.
• Insider threats: The actor may also leverage trusted insiders, even unwitting ones, for collecting information. Social engineering often elicits a wealth of information from people looking for a new job or even just trying to help.
• Enterprise networks: The actor may compromise enterprise IT networks and collect and exfiltrate ICS-related information. Procurement documents, engineering specifications, and even configurations may be stored on corporate IT networks.

In addition to OT-specific intelligence, information about IT technologies used in control systems is widely available. Knowledge that was once limited to control system engineers and OT operators has become easily available as IT technologies move into more of the control system environment. Control system vendors, in conjunction with the owner/operator community, have continually optimized and reduced the cost of engineering, operating, and maintaining control systems by incorporating more commodity IT components and technologies in some parts of OT environments. These advancements sometimes can make information about some systems easily available, thereby increasing the risk of cyber exploitation. 

Develop techniques and tools

Using the intelligence collected about the control system’s design, a cyber actor may procure systems that are similar to the target and configure them as mock-up versions for practice purposes. Nation-state actors can easily obtain most control system equipment. Groups with limited means can still often acquire control systems through willing vendors and secondhand resellers.

Access to a mock-up of the target system enables an actor to determine the most effective tools and techniques. A cyber actor can leverage resident system utilities, available exploitation tools; or, if necessary, develop or purchase custom tools to affect the control system. Utilities that are already on the system can be used to reconfigure settings and may have powerful troubleshooting capabilities. 

As the control system community has incorporated commodity IT and modernized OT, the community has simplified the tools, techniques, scripts, and software packages used in control systems. As a result, a multitude of convenient tools are readily available to exploit IT and OT systems.

Actors may also develop custom ICS-focused malware based on their knowledge of the control systems. For example, TRITON malware was designed to target certain versions of Triconex Tricon programmable logic controllers (PLCs) by modifying in-memory firmware to add additional programming. The extra functionality allows an actor to read/modify memory contents and execute custom code, disabling the safety system. [13] APT actors have also developed tools to scan for, compromise, and control certain Schneider Electric PLCs, OMRON Sysmac NEX PLCs, and Open Platform Communications Unified Architecture (OPC UA) servers. [9] 

With TTPs in place, a cyber actor is prepared to do virtually anything that a normal system operator can, and potentially much more.

Gain initial access to the system

To leverage the techniques and tools that they developed and practiced, cyber actors must first gain access to the targeted system. 

Most modern control systems maintain remote access capabilities allowing vendors, integrators, service providers, owners, and operators access to the system. Remote access enables these parties to perform remote monitoring services, diagnose problems remotely, and verify warranty agreements. 

However, these access points often have poor security practices, such as using default and maintenance passwords. Malicious cyber actors can leverage these access points as vectors to covertly gain access to the system, exfiltrate data, and launch other cyber activities before an operator realizes there is a problem. Malicious actors can use web-based search platforms, such as Shodan, to identify these exposed access points. 

Vendor access to control systems typically use connections that create a bridge between control system networks and external environments. Often unknown to the owner/operator, this bridge provides yet another path for cyber exploitation and allows cyber actors to take advantage of vulnerabilities in other infrastructure to gain access to the control system. 

Remote access points and methodologies use a variety of access and communication protocols. Many are nothing more than vendor-provided dial-up modems and network switches protected only by obscurity and passwords. Some are dedicated devices and services that communicate via more secure virtual private networks (VPNs) and encryption. Few, if any, offer robust cybersecurity capabilities to protect the control system access points or prevent the transmission of acquired data outside the relatively secure environment of the isolated control system. This access to an ostensibly closed control system can be used to exploit the network and components.

Execute techniques and tools to create the intended effects

Once an actor gains initial access to targeted OT/ICS system, the actor will execute techniques, tools, and malware to achieve the intended effects on the target system. To disrupt, disable, deny, deceive, and/or destroy the system, the malicious actor often performs, in any order or in combination, the following activities:

1. Degrade the operator’s ability to monitor the targeted system or degrade the operator’s confidence in the control system’s ability to operate, control, and monitor the targeted system. Functionally, an actor could prevent the operator’s display (human machine interface, or HMI) from being updated and selectively update or change visualizations on the HMI, as witnessed during the attack on the Ukraine power grid. [5] (Manipulation of View [T0832] )
2. Operate the targeted control system. Functionally, this includes the ability to modify analog and digital values internal to the system (changing alarms and adding or modifying user accounts), or to change output control points — this includes abilities such as altering tap changer output signals, turbine speed demand, and opening and closing breakers. (Manipulation of Control [T0831])
3. Impair the system’s ability to report data. Functionally, this is accomplished by degrading or disrupting communications with external communications circuits (e.g., ICCP , HDLC , PLC , VSAT, SCADA radio, other radio frequency mediums), remote terminal units (RTUs) or programmable logic controllers (PLCs), connected business or corporate networks, HMI subnetworks, other remote I/O, and any connected Historian/bulk data storage. (Block Reporting Message [T0804], Denial of View [T0815])
4. Deny the operator’s ability to control the targeted system. Functionally, this includes the ability to stop, abort, or corrupt the system’s operating system (OS) or the supervisory control and data acquisition (SCADA) system’s software functionality. (Denial of Control [T0813])
5. Enable remote or local reconnaissance on the control system. Functionally, an actor could obtain system configuration information to enable development of a modified system configuration or a custom tool. (Collection [TA0100], Theft of Operational Information [T0882])

Using these techniques, cyber actors could cause various physical consequences. They could open or close breakers, throttle valves, overfill tanks, set turbines to over-speed, or place plants in unsafe operating conditions. Additionally, cyber actors could manipulate the control environment, obscuring operator awareness and obstructing recovery, by locking interfaces and setting monitors to show normal conditions. Actors can even suspend alarm functionality, allowing the system to operate under unsafe conditions without alerting the operator. Even when physical safety systems should prevent catastrophic physical consequences, more limited effects are possible and could be sufficient to meet the actor’s intent. In some scenarios though, if an actor simultaneously manipulates multiple parts of the system, the physical safety systems may not be enough. Impacts to the system could be temporary or permanent, potentially even including physical destruction of equipment. 

Mitigations

The complexity of balancing network security with performance, features, ease-of-use, and availability can be overwhelming for owner/operators. This is especially true where system tools and scripts enable ease-of-use and increase availability or functionality of the control network; and when equipment vendors require remote access for warranty     compliance, service obligations, and financial/billing functionality. However, with the increase in targeting of OT/ICS by malicious actors, owner/operators should be more cognizant of the risks when making these balancing decisions. Owner/operators should also carefully consider what information about their systems needs to be publicly available and determine if each external connection is truly needed. [1] 

System owners and operators cannot prevent a malicious actor from targeting their systems. Understanding that being targeted is not an “if” but a “when” is essential context for making ICS security decisions. By assuming that the system is being targeted and predicting the effects that a malicious actor would intend to cause, owner/operators can employ and prioritize mitigation actions.

However, the variety of available security solutions can also be intimidating, resulting in choice paralysis. In the midst of so many options, owner/operators may be unable to incorporate simple security and administrative strategies that could mitigate many of the common and realistic threats. Fortunately, owner/operators can apply a few straightforward ICS security best practices to counter adversary TTPs. 

Limit exposure of system information

Operational and system information and configuration data is a key element of critical infrastructure operations. The importance of keeping such data confidential cannot be overstated. To the extent possible, avoid disclosing information about system hardware, firmware, and software in any public forum. Incorporate information protection education into training for personnel. Limit information that is sent out from the system.

Document the answers to the following questions:

1. From where and to where is data flowing?
2. How are the communication pathways documented and how is the data secured/encrypted?
3. How is the data used and secured when it arrives at its destination?
4. What are the network security standards at the data destination, whether a vendor/regulator or administrator/financial institution? 
5. Can the data be shared further once at its destination? Who has the authority to share this data?

Eliminate all other data destinations. Share only the data necessary to comply with applicable legal requirements, such as those contractually required by vendors—nothing more. Do not allow other uses of the data and other accesses to the system without strict administrative policies designed specifically to protect the data. Prevent new connections to the control system using strict administrative accountability. Ensure strict agreements are in place with outside systems/vendors when it comes to sharing, access, and use. Have strong policies for the destruction of such data. Audit policies and procedures to verify compliance and secure data once it gets to its destination, and determine who actually has access to it. 

Identify and secure remote access points

Owner/operators must maintain detailed knowledge of all installed systems, including which remote access points are—or could be—operating in the control system network. Creating a full “connectivity inventory” is a critical step in securing access to the system.

Many vendor-provided devices maintain these access capabilities as an auxiliary function and may have services that will automatically ‘phone home’ in an attempt to register and update software or firmware. A vendor may also have multiple access points to cover different tasks. 

Once owner/operators have identified all remote access points on their systems, they can implement the following recommendations to improve their security posture:

• Reduce the attack surface by proactively limiting and hardening Internet-exposed assets. See CISA’s Get Your Stuff Off Search page for more information.
• Establish a firewall and a demilitarized zone (DMZ) between the control system and the vendor’s access points and devices. Do not allow direct access into the system; use an intermediary service to share only necessary data and only when required. For more information see CISA’s infographic Layering Network Security Through Segmentation. [14]
• Consider using virtual private networks (VPNs) at specific points to and from the system rather than allowing separate access points for individual devices or vendors.
• Utilize jump boxes to isolate and monitor access to the system.
• Ensure that data can only flow outward from the system – administratively and physically. Use encrypted links to exchange data outside of the system.
• Enforce strict compliance with policies and procedures for remote access, even if personnel complain that it is too difficult.
• If the system does not use vendor access points and devices, ensure that none are active. Use strict hardware, software, and administrative techniques to prevent them from becoming covertly active.
• Do not allow vendor-provided system access devices and software to operate continuously in the system without full awareness of their security posture and access logs.
• Install and keep current all vendor-provided security systems associated with the installed vendor access points.
• Review configurations to ensure they are configured securely. Operators typically focus on necessary functionality, so properly securing the configurations and remote access may be overlooked. 
• Consider penetration testing to validate the system’s security posture and any unknown accesses or access vulnerabilities. 
• Add additional security features to the system as needed. Do not assume that one vendor has a monopoly on the security of their equipment; other vendors may produce security features to fill gaps. 
• Change all default passwords throughout the system and update any products with hard-coded passwords, especially in all remote access and security components.
• Patch known exploited vulnerabilities whenever possible. Prioritize timely patching of all remote access points. Keep operating systems, firewalls, and all security features up-to-date.
• Continually monitor remote access logs for suspicious accesses. Securely aggregate logs for easier monitoring.

Restrict tools and scripts 

Limit access to network and control system application tools and scripts to legitimate users performing legitimate tasks on the control system. Removing the tools and scripts entirely and patching embedded control system components for exploitable vulnerabilities is often not feasible. Thus, carefully apply access and use limitations to particularly vulnerable processes and components to limit the threat.

The control system and any accompanying vendor access points may have been delivered with engineering, configuration, and diagnostic tools pre-installed. Engineers use these tools to configure and modify the system and its processes as needed. However, such tools can also be used by a malicious actor to manipulate the system, without needing any special additional tools. Using the system against itself is a powerful cyber exploitation technique. Mitigations strategies include:

1. Identify any engineering, configuration, or diagnostic tools.
2. Securely store gold copies of these tools external to the system if possible.
3. Remove all non-critical tools.
4. Prevent these tools from being reinstalled.
5. Perform routine audits to check that these tools have not been reinstalled.

Conduct regular security audits

The owner/operator of the control system should consider performing an independent security audit of the system, especially of third-party vendor access points and systems. The owner/operator cannot solely depend on the views, options, and guidance of the vendor/integrator that designed, developed, or sold the system. The goal of such an audit is to identify and document system vulnerabilities, practices, and procedures that should be eliminated to improve the cyber defensive posture, and ultimately prevent malicious cyber actors from being able to cause their intended effects. Steps to consider during an audit include the following:

1. Validate all connections (e.g., network, serial, modem, wireless, etc.).
2. Review system software patching procedures.
3. Confirm secure storage of gold copies (e.g., OS, firmware, patches, configurations, etc.).
4. Verify removal from the system of all non-critical software, services, and tools.
5. Audit the full asset inventory. 
6. Implement CISA ICS mitigations and best practices. [15] [16]
7. Monitor system logs and intrusion detection system (IDS) logs.

Implement a dynamic network environment

Static network environments provide malicious actors with persistent knowledge of the system. A static network can provide cyber actors the opportunity to collect bits of intelligence about the system over time, establish long-term accesses into the system, and develop the tools and TTPs to affect the control system as intended. 

While it may be unrealistic for the administrators of many OT/ICS environments to make regular non-critical changes, owner/operators should consider periodically making manageable network changes. A little change can go a long way to disrupt previously obtained access by a malicious actor. Consider the following:

1. Deploy additional firewalls and routers from different vendors.
2. Modify IP address pools.
3. Replace outdated hardware (e.g., workstations, servers, printers, etc.).
4. Upgrade operating systems.
5. Install or upgrade commercially available security packages for vendor access points and methodologies.

Planning these changes with significant forethought can help minimize the impact on network operation.

Owner/operators should familiarize themselves with the risks to the system as outlined by the product vendor. These may be described in manuals as the system using insecure protocols for interoperability or certain configurations that may expose the system in additional ways. Changes to the system to reduce these risks should be considered and implemented when feasible.

Conclusion

The combination of integrated, simplified tools and remote accesses creates an environment ripe for malicious actors to target control systems networks. New IT-enabled accesses provide cyber actors with a larger attack surface into cyber-physical environments. It is vital for OT/ICS defenders to anticipate the TTPs of cyber actors combining IT expertise with engineering know-how. Defenders can employ the mitigations listed in this advisory to limit unauthorized access, lock down tools and data flows, and deny malicious actors from achieving their desired effects. 

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.

Purpose

This advisory was developed by NSA and CISA in furtherance of their cybersecurity missions, including their responsibilities to develop and issue cybersecurity specifications and mitigations. This information may be shared broadly to reach all appropriate stakeholders.
 

Contact Information

For NSA client requirements or general cybersecurity inquiries, contact Cybersecurity_Requests@nsa.gov. To report incidents and anomalous activity or to request incident response resources or technical assistance related to these threats, contact CISA at report@cisa.gov. 

Media Inquiries / Press Desk: 

• NSA Media Relations, 443-634-0721, MediaRelations@nsa.gov 
• CISA Media Relations, 703-235-2010, CISAMedia@cisa.dhs.gov 

References

• [1] National Security Agency (2021), Stop Malicious Cyber Activity Against Connected Operational Technology.
• [2] National Security Agency and Cybersecurity and Infrastructure Security Agency (2020), NSA and CISA Recommend Immediate Actions to Reduce Exposure Across all Operational Technologies and Control Systems.
• [3] Tenable (2018), The Challenges of Securing Industrial Control Systems from Cyberattacks.
• [4] Cybersecurity and Infrastructure Security Agency (2022), Russian State-Sponsored and Criminal Cyber Threats to Critical Infrastructure.
• [5] Cybersecurity and Infrastructure Security Agency (2021), Cyber-Attack Against Ukrainian Critical Infrastructure.
• [6] Cybersecurity and Infrastructure Security Agency (2021), Ongoing Cyber Threats to U.S. Water and Wastewater Systems.
• [7] Cybersecurity and Infrastructure Security Agency (2020), Ransomware Impacting Pipeline Operations.
• [8] Cybersecurity and Infrastructure Security Agency (2021), Chinese Gas Pipeline Intrusion Campaign, 2011 to 2013
• [9] Cybersecurity and Infrastructure Security Agency (2022), APT Cyber Tools Targeting ICS/SCADA Devices
• [10] Cybersecurity and Infrastructure Security Agency (2022), Tactics, Techniques, and Procedures of Indicted State-Sponsored Russian Cyber Actors Targeting the Energy Sector.
• [11] The American Society of Mechanical Engineers (2016), Securing the Power Grid Against Cyber Attack.
• [12] PBS FRONTLINE (2003), Vulnerability: the power grid?
• [13] Cybersecurity and Infrastructure Security Agency (2018), Schneider Electric Triconex Tricon (Update B).
• [14] Cybersecurity and Infrastructure Security Agency (2022), Layering Network Security Through Segmentation.
• [15] Cybersecurity and Infrastructure Security Agency, Recommended Cybersecurity Practices for Industrial Control Systems.
• [16] Cybersecurity and Infrastructure Security Agency Industrial Control Systems Cyber Emergency Response Team (2016), Recommended Practice: Improving Industrial Control System Cybersecurity with Defense-in-Depth Strategies

Revisions

• Initial Release: September 22, 2022

Source de l’article sur us-cert.gov

Original release date: September 6, 2022

Summary

Actions to take today to mitigate cyber threats from ransomware:

• Prioritize and remediate known exploited vulnerabilities.
• Train users to recognize and report phishing attempts.
• Enable and enforce 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.