Below is a list of all 79 techniques in ATT&CK for ICS:
|Activate Firmware Update Mode||Inhibit Response Function||T0800||Adversaries may activate firmware update mode on devices to prevent expected response functions from engaging in reaction to an emergency or process malfunction. For example, devices such as protection relays may have an operation mode designed for firmware installation. This mode may halt process monitoring and related functions to allow new firmware to be loaded. A device left in update mode may be placed in an inactive holding state if no firmware is provided to it. By entering and leaving a device in this mode, the adversary may deny its usual functionalities.|
|Alarm Suppression||Inhibit Response Function||T0878||Adversaries may target protection function alarms to prevent them from notifying operators of critical conditions. Alarm messages may be a part of an overall reporting system and of particular interest for adversaries. Disruption of the alarm system does not imply the disruption of the reporting system as a whole.
In the Maroochy Attack, the adversary suppressed alarm reporting to the central computer.1
A Secura presentation on targeting OT notes a dual fold goal for adversaries attempting alarm suppression: prevent outgoing alarms from being raised and prevent incoming alarms from being responded to.2 The method of suppression may greatly depend on the type of alarm in question:
|Automated Collection||Collection||T0802||Adversaries may automate collection of industrial environment information using tools or scripts. This automated collection may leverage native control protocols and tools available in the control systems environment. For example, the OPC protocol may be used to enumerate and gather information. Access to a system or interface with these native protocols may allow collection and enumeration of other attached, communicating servers and devices.|
|Block Command Message||Inhibit Response Function||T0803||Adversaries may block a command message from reaching its intended target to prevent command execution. In OT networks, command messages are sent to provide instructions to control system devices. A blocked command message can inhibit response functions from correcting a disruption or unsafe condition.34|
|Block Reporting Message||Inhibit Response Function||T0804||Adversaries may block or prevent a reporting message from reaching its intended target. In control systems, reporting messages contain telemetry data (e.g., I/O values) pertaining to the current state of equipment and the industrial process. By blocking these reporting messages, an adversary can potentially hide their actions from an operator. Blocking reporting messages in control systems that manage physical processes may contribute to system impact, causing inhibition of a response function. A control system may not be able to respond in a proper or timely manner to an event, such as a dangerous fault, if its corresponding reporting message is blocked.34|
|Block Serial COM||Inhibit Response Function||T0805||Adversaries may block access to serial COM to prevent instructions or configurations from reaching target devices. Serial Communication ports (COM) allow communication with control system devices. Devices can receive command and configuration messages over such serial COM. Devices also use serial COM to send command and reporting messages. Blocking device serial COM may also block command messages and block reporting messages.
A serial to Ethernet converter is often connected to a serial COM to facilitate communication between serial and Ethernet devices. One approach to blocking a serial COM would be to create and hold open a TCP session with the Ethernet side of the converter. A serial to Ethernet converter may have a few ports open to facilitate multiple communications. For example, if there are three serial COM available -- 1, 2 and 3 --, the converter might be listening on the corresponding ports 20001, 20002, and 20003. If a TCP/IP connection is opened with one of these ports and held open, then the port will be unavailable for use by another party. One way the adversary could achieve this would be to initiate a TCP session with the serial to Ethernet converter at |
|Brute Force I/O||Impair Process Control||T0806||Adversaries may brute force I/O addresses on a device and attempt to exhaustively perform an action. By enumerating the full range of I/O addresses, an adversary may manipulate a process function without having to target specific I/O interfaces. More than one process function manipulation and enumeration pass may occur on the targeted I/O range in a brute force attempt.|
|Change Operating Mode||Execution|
|T0858||Adversaries may change the operating mode of a controller to gain additional access to engineering functions such as Program Download.
Programmable controllers typically have several modes of operation that control the state of the user program and control access to the controller’s API. Operating modes can be physically selected using a key switch on the face of the controller but may also be selected with calls to the controller’s API. Operating modes and the mechanisms by which they are selected often vary by vendor and product line. Some commonly implemented operating modes are described below:
|Command-Line Interface||Execution||T0807||Adversaries may utilize command-line interfaces (CLIs) to interact with systems and execute commands. CLIs provide a means of interacting with computer systems and are a common feature across many types of platforms and devices within control systems environments.9 Adversaries may also use CLIs to install and run new software, including malicious tools that may be installed over the course of an operation.
CLIs are typically accessed locally, but can also be exposed via services, such as SSH, Telnet, and RDP. Commands that are executed in the CLI execute with the current permissions level of the process running the terminal emulator, unless the command specifies a change in permissions context.Many controllers have CLI interfaces for management purposes.
|Commonly Used Port||Command and Control||T0885||Adversaries may communicate over a commonly used port to bypass firewalls or network detection systems and to blend in with normal network activity, to avoid more detailed inspection. They may use the protocol associated with the port, or a completely different protocol. They may use commonly open ports, such as the examples provided below.
|Connection Proxy||Command and Control||T0884||Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications.
The definition of a proxy can also be expanded to encompass trust relationships between networks in peer-to-peer, mesh, or trusted connections between networks consisting of hosts or systems that regularly communicate with each other.The network may be within a single organization or across multiple organizations with trust relationships. Adversaries could use these types of relationships to manage command and control communications, to reduce the number of simultaneous outbound network connections, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion.10
|Damage to Property||Impact||T0879||Adversaries may cause damage and destruction of property to infrastructure, equipment, and the surrounding environment when attacking control systems. This technique may result in device and operational equipment breakdown, or represent tangential damage from other techniques used in an attack. Depending on the severity of physical damage and disruption caused to control processes and systems, this technique may result in Loss of Safety. Operations that result in Loss of Control may also cause damage to property, which may be directly or indirectly motivated by an adversary seeking to cause impact in the form of Loss of Productivity and Revenue.
The German Federal Office for Information Security (BSI) reported a targeted attack on a steel mill under an incidents affecting business section of its 2014 IT Security Report.11 These targeted attacks affected industrial operations and resulted in breakdowns of control system components and even entire installations. As a result of these breakdowns, massive impact and damage resulted from the uncontrolled shutdown of a blast furnace.
In the Maroochy Attack, Vitek Boden gained remote computer access to the control system and altered data so that whatever function should have occurred at affected pumping stations did not occur or occurred in a different way. This ultimately led to 800,000 liters of raw sewage being spilled out into the community. The raw sewage affected local parks, rivers, and even a local hotel. This resulted in harm to marine life and produced a sickening stench from the community's now blackened rivers.1A Polish student used a remote controller device to interface with the Lodz city tram system in Poland.121314 Using this remote, the student was able to capture and replay legitimate tram signals. This resulted in damage to impacted trams, people, and the surrounding property. Reportedly, four trams were derailed and were forced to make emergency stops.13 Commands issued by the student may have also resulted in tram collisions, causing harm to those on board and the environment outside.14
|Data Destruction||Inhibit Response Function||T0809||Adversaries may perform data destruction over the course of an operation. The adversary may drop or create malware, tools, or other non-native files on a target system to accomplish this, potentially leaving behind traces of malicious activities. Such non-native files and other data may be removed over the course of an intrusion to maintain a small footprint or as a standard part of the post-intrusion cleanup process.15
Data destruction may also be used to render operator interfaces unable to respond and to disrupt response functions from occurring as expected. An adversary may also destroy data backups that are vital to recovery after an incident.Standard file deletion commands are available on most operating system and device interfaces to perform cleanup, but adversaries may use other tools as well. Two examples are Windows Sysinternals SDelete and Active@ Killdisk.
|Data Historian Compromise||Initial Access||T0810||Adversaries may compromise and gain control of a data historian to gain a foothold into the control system environment. Access to a data historian may be used to learn stored database archival and analysis information on the control system. A dual-homed data historian may provide adversaries an interface from the IT environment to the OT environment. Dragos has released an updated analysis on CrashOverride that outlines the attack from the ICS network breach to payload delivery and execution.16 The report summarized that CrashOverride represents a new application of malware, but relied on standard intrusion techniques. In particular, new artifacts include references to a Microsoft Windows Server 2003 host, with a SQL Server. Within the ICS environment, such a database server can act as a data historian. Dragos noted a device with this role should be "expected to have extensive connections" within the ICS environment. Adversary activity leveraged database capabilities to perform reconnaissance, including directory queries and network connectivity checks.|
|Data from Information Repositories||Collection||T0811||Adversaries may target and collect data from information repositories. This can include sensitive data such as specifications, schematics, or diagrams of control system layouts, devices, and processes. Examples of information repositories include reference databases or local machines in the process environment, as well as workstations and databases in the corporate network that might contain information about the ICS. 17 Information collected from these systems may provide the adversary with a better understanding of the operational environment, vendors used, processes, or procedures of the ICS.|
|Default Credentials||Lateral Movement||T0812||Adversaries may leverage manufacturer or supplier set default credentials on control system devices. These default credentials may have administrative permissions and may be necessary for initial configuration of the device. It is general best practice to change the passwords for these accounts as soon as possible, but some manufacturers may have devices that have passwords or usernames that cannot be changed.18 Default credentials are normally documented in an instruction manual that is either packaged with the device, published online through official means, or published online through unofficial means. Adversaries may leverage default credentials that have not been properly modified or disabled.|
|Denial of Control||Impact||T0813||Adversaries may cause a denial of control to temporarily prevent operators and engineers from interacting with process controls. An adversary may attempt to deny process control access to cause a temporary loss of communication with the control device or to prevent operator adjustment of process controls. An affected process may still be operating during the period of control loss, but not necessarily in a desired state.192021
In the Maroochy attack, the adversary was able to temporarily shut an investigator out of the network preventing them from issuing any controls.In the 2017 Dallas Siren incident operators were unable to disable the false alarms from the Office of Emergency Management headquarters.22
|Denial of Service||Inhibit Response Function||T0814||Adversaries may perform Denial-of-Service (DoS) attacks to disrupt expected device functionality. Examples of DoS attacks include overwhelming the target device with a high volume of requests in a short time period and sending the target device a request it does not know how to handle. Disrupting device state may temporarily render it unresponsive, possibly lasting until a reboot can occur. When placed in this state, devices may be unable to send and receive requests, and may not perform expected response functions in reaction to other events in the environment.
Some ICS devices are particularly sensitive to DoS events, and may become unresponsive in reaction to even a simple ping sweep. Adversaries may also attempt to execute a Permanent Denial-of-Service (PDoS) against certain devices, such as in the case of the BrickerBot malware.23
Adversaries may exploit a software vulnerability to cause a denial of service by taking advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Vulnerabilities may exist in software that can be used to cause a or denial of service condition.
Adversaries may have prior knowledge about industrial protocols or control devices used in the environment through Remote System Information Discovery. There are examples of adversaries remotely causing a Device Restart/Shutdown by exploiting a vulnerability that induces uncontrolled resource consumption.242526In the Maroochy attack, the adversary was able to shut an investigator out of the network.1
|Denial of View||Impact||T0815||Adversaries may cause a denial of view in attempt to disrupt and prevent operator oversight on the status of an ICS environment. This may manifest itself as a temporary communication failure between a device and its control source, where the interface recovers and becomes available once the interference ceases.192021
An adversary may attempt to deny operator visibility by preventing them from receiving status and reporting messages. Denying this view may temporarily block and prevent operators from noticing a change in state or anomalous behavior. The environment's data and processes may still be operational, but functioning in an unintended or adversarial manner.In the Maroochy attack, the adversary was able to temporarily shut an investigator out of the network, preventing them from viewing the state of the system.
|Detect Operating Mode||Collection||T0868||Adversaries may gather information about a PLC’s or controller’s current operating mode. Operating modes dictate what change or maintenance functions can be manipulated and are often controlled by a key switch on the PLC (e.g., run, prog [program], and remote). Knowledge of these states may be valuable to an adversary to determine if they are able to reprogram the PLC. Operating modes and the mechanisms by which they are selected often vary by vendor and product line. Some commonly implemented operating modes are described below:
|Device Restart/Shutdown||Inhibit Response Function||T0816||Adversaries may forcibly restart or shutdown a device in an ICS environment to disrupt and potentially negatively impact physical processes. Methods of device restart and shutdown exist in some devices as built-in, standard functionalities. These functionalities can be executed using interactive device web interfaces, CLIs, and network protocol commands.
Unexpected restart or shutdown of control system devices may prevent expected response functions happening during critical states.A device restart can also be a sign of malicious device modifications, as many updates require a shutdown in order to take effect.
|Drive-by Compromise||Initial Access||T0817||Adversaries may gain access to a system during a drive-by compromise, when a user visits a website as part of a regular browsing session.With this technique, the user's web browser is targeted and exploited simply by visiting the compromised website.
The adversary may target a specific community, such as trusted third party suppliers or other industry specific groups, which often visit the target website. This kind of targeted attack relies on a common interest, and is known as a strategic web compromise or watering hole attack.The National Cyber Awareness System (NCAS) has issued a Technical Alert (TA) regarding Russian government cyber activity targeting critical infrastructure sectors.17 Analysis by DHS and FBI has noted two distinct categories of victims in the Dragonfly campaign on the Western energy sector: staging and intended targets. The adversary targeted the less secure networks of staging targets, including trusted third-party suppliers and related peripheral organizations. Initial access to the intended targets used watering hole attacks to target process control, ICS, and critical infrastructure related trade publications and informational websites.
|Engineering Workstation Compromise||Initial Access||T0818||Adversaries may compromise and gain control of an engineering workstation for Initial Access into the control system environment. Access to an engineering workstation may occur through or physical means, such as a Valid Accounts with privileged access or infection by removable media. A dual-homed engineering workstation may allow the adversary access into multiple networks. For example, unsegregated process control, safety system, or information system networks.
An Engineering Workstation is designed as a reliable computing platform that configures, maintains, and diagnoses control system equipment and applications. Compromise of an engineering workstation may provide access to, and control of, other control system applications and equipment.In the Maroochy attack, the adversary utilized a computer, possibly stolen, with proprietary engineering software to communicate with a wastewater system.1
|Execution through API||Execution||T0871||Adversaries may attempt to leverage Application Program Interfaces (APIs) used for communication between control software and the hardware. Specific functionality is often coded into APIs which can be called by software to engage specific functions on a device or other software.|
|Exploit Public-Facing Application||Initial Access||T0819||Adversaries may leverage weaknesses to exploit internet-facing software for initial access into an industrial network. Internet-facing software may be user applications, underlying networking implementations, an assets operating system, weak defenses, etc. Targets of this technique may be intentionally exposed for the purpose of remote management and visibility. An adversary may seek to target public-facing applications as they may provide direct access into an ICS environment or the ability to move into the ICS network. Publicly exposed applications may be found through online tools that scan the internet for open ports and services. Version numbers for the exposed application may provide adversaries an ability to target specific known vulnerabilities. Exposed control protocol or remote access ports found in Commonly Used Port may be of interest by adversaries.|
|Exploitation for Evasion||Evasion||T0820||Adversaries may exploit a software vulnerability to take advantage of a programming error in a program, service, or within the operating system software or kernel itself to evade detection. Vulnerabilities may exist in software that can be used to disable or circumvent security features. Adversaries may have prior knowledge through Remote System Information Discovery about security features implemented on control devices. These device security features will likely be targeted directly for exploitation. There are examples of firmware RAM/ROM consistency checks on control devices being targeted by adversaries to enable the installation of malicious System Firmware.|
|Exploitation for Privilege Escalation||Privilege Escalation||T0890||Adversaries may exploit software vulnerabilities in an attempt to elevate privileges. Exploitation of a software vulnerability occurs when an adversary takes advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Security constructs such as permission levels will often hinder access to information and use of certain techniques, so adversaries will likely need to perform privilege escalation to include use of software exploitation to circumvent those restrictions.27 When initially gaining access to a system, an adversary may be operating within a lower privileged process which will prevent them from accessing certain resources on the system. Vulnerabilities may exist, usually in operating system components and software commonly running at higher permissions, that can be exploited to gain higher levels of access on the system. This could enable someone to move from unprivileged or user level permissions to SYSTEM or root permissions depending on the component that is vulnerable. This may be a necessary step for an adversary compromising an endpoint system that has been properly configured and limits other privilege escalation methods.27|
|Exploitation of Remote Services||Lateral Movement|
|T0866||Adversaries may exploit a software vulnerability to take advantage of a programming error in a program, service, or within the operating system software or kernel itself to enable remote service abuse. A common goal for post-compromise exploitation of remote services is for initial access into and lateral movement throughout the ICS environment to enable access to targeted systems.28 ICS asset owners and operators have been affected by ransomware (or disruptive malware masquerading as ransomware) migrating from enterprise IT to ICS environments: WannaCry, NotPetya, and BadRabbit. In each of these cases, self-propagating (“wormable”) malware initially infected IT networks, but through exploit (particularly the SMBv1-targeting MS17-010 vulnerability) spread to industrial networks, producing significant impacts.29|
|External Remote Services||Initial Access||T0822||Adversaries may leverage external remote services as a point of initial access into your network. These services allow users to connect to internal network resources from external locations. Examples are VPNs, Citrix, and other access mechanisms. Remote service gateways often manage connections and credential authentication for these services.30
External remote services allow administration of a control system from outside the system. Often, vendors and internal engineering groups have access to external remote services to control system networks via the corporate network. In some cases, this access is enabled directly from the internet. While remote access enables ease of maintenance when a control system is in a remote area, compromise of remote access solutions is a liability. The adversary may use these services to gain access to and execute attacks against a control system network. Access to valid accounts is often a requirement.
As they look for an entry point into the control system network, adversaries may begin searching for existing point‐to‐point VPN implementations at trusted third party networks or through remote support employee connections where split tunneling is enabled.4In the Maroochy Attack, the adversary was able to gain remote computer access to the system over radio.
|Graphical User Interface||Execution||T0823||Adversaries may attempt to gain access to a machine via a Graphical User Interface (GUI) to enhance execution capabilities. Access to a GUI allows a user to interact with a computer in a more visual manner than a CLI. A GUI allows users to move a cursor and click on interface objects, with a mouse and keyboard as the main input devices, as opposed to just using the keyboard. If physical access is not an option, then access might be possible via protocols such as VNC on Linux-based and Unix-based operating systems, and RDP on Windows operating systems. An adversary can use this access to execute programs and applications on the target machine.|
|T0874||Adversaries may hook into application programming interface (API) functions used by processes to redirect calls for execution and privilege escalation means. Windows processes often leverage these API functions to perform tasks that require reusable system resources. Windows API functions are typically stored in dynamic-link libraries (DLLs) as exported functions.31 One type of hooking seen in ICS involves redirecting calls to these functions via import address table (IAT) hooking. IAT hooking uses modifications to a process’s IAT, where pointers to imported API functions are stored.32|
|I/O Image||Collection||T0877||Adversaries may seek to capture process image values related to the inputs and outputs of a PLC. Within a PLC all input and output states are stored into an I/O image. This image is used by the user program instead of directly interacting with physical I/O.33|
|Indicator Removal on Host||Evasion||T0872||Adversaries may attempt to remove indicators of their presence on a system in an effort to cover their tracks. In cases where an adversary may feel detection is imminent, they may try to overwrite, delete, or cover up changes they have made to the device.|
|Internet Accessible Device||Initial Access||T0883||Adversaries may gain access into industrial environments through systems exposed directly to the internet for remote access rather than through External Remote Services. Internet Accessible Devices are exposed to the internet unintentionally or intentionally without adequate protections. This may allow for adversaries to move directly into the control system network. Access onto these devices is accomplished without the use of exploits, these would be represented within the Exploit Public-Facing Application technique.
Adversaries may leverage built in functions for remote access which may not be protected or utilize minimal legacy protections that may be targeted.34 These services may be discoverable through the use of online scanning tools.
In the case of the Bowman dam incident, adversaries leveraged access to the dam control network through a cellular modem. Access to the device was protected by password authentication, although the application was vulnerable to brute forcing.343536In Trend Micro’s manufacturing deception operations adversaries were detected leveraging direct internet access to an ICS environment through the exposure of operational protocols such as Siemens S7, Omron FINS, and EtherNet/IP, in addition to misconfigured VNC access.37
|Lateral Tool Transfer||Lateral Movement||T0867||Adversaries may transfer tools or other files from one system to another to stage adversary tools or other files over the course of an operation.38 Copying of files may also be performed laterally between internal victim systems to support Lateral Movement with remote Execution using inherent file sharing protocols such as file sharing over SMB to connected network shares.38 In control systems environments, malware may use SMB and other file sharing protocols to move laterally through industrial networks.|
|Loss of Availability||Impact||T0826||Adversaries may attempt to disrupt essential components or systems to prevent owner and operator from delivering products or services.192021 Adversaries may leverage malware to delete or encrypt critical data on HMIs, workstations, or databases.|
|Loss of Control||Impact||T0827||Adversaries may seek to achieve a sustained loss of control or a runaway condition in which operators cannot issue any commands even if the malicious interference has subsided.192021 The German Federal Office for Information Security (BSI) reported a targeted attack on a steel mill in its 2014 IT Security Report.11 These targeted attacks affected industrial operations and resulted in breakdowns of control system components and even entire installations. As a result of these breakdowns, massive impact resulted in damage and unsafe conditions from the uncontrolled shutdown of a blast furnace.|
|Loss of Productivity and Revenue||Impact||T0828||Adversaries may cause loss of productivity and revenue through disruption and even damage to the availability and integrity of control system operations, devices, and related processes. This technique may manifest as a direct effect of an ICS-targeting attack or tangentially, due to an IT-targeting attack against non-segregated environments. In some cases, this may result from the postponement and disruption of ICS operations and production as part of a remediation effort. Operations may be brought to a halt and effectively stopped in an effort to contain and properly remove malware or due to the Loss of Safety.|
|Loss of Protection||Impact||T0837||Adversaries may compromise protective system functions designed to prevent the effects of faults and abnormal conditions. This can result in equipment damage, prolonged process disruptions and hazards to personnel.
Many faults and abnormal conditions in process control happen too quickly for a human operator to react to. Speed is critical in correcting these conditions to limit serious impacts such as Loss of Control and Property Damage.Adversaries may target and disable protective system functions as a prerequisite to subsequent attack execution or to allow for future faults and abnormal conditions to go unchecked. Detection of a Loss of Protection by operators can result in the shutdown of a process due to strict policies regarding protection systems. This can cause a Loss of Productivity and Revenue and may meet the technical goals of adversaries seeking to cause process disruptions.
|Loss of Safety||Impact||T0880||Adversaries may compromise safety system functions designed to maintain safe operation of a process when unacceptable or dangerous conditions occur. Safety systems are often composed of the same elements as control systems but have the sole purpose of ensuring the process fails in a predetermined safe manner.
Many unsafe conditions in process control happen too quickly for a human operator to react to. Speed is critical in correcting these conditions to limit serious impacts such as Loss of Control and Property Damage.Adversaries may target and disable safety system functions as a prerequisite to subsequent attack execution or to allow for future unsafe conditionals to go unchecked. Detection of a Loss of Safety by operators can result in the shutdown of a process due to strict policies regarding safety systems. This can cause a Loss of Productivity and Revenue and may meet the technical goals of adversaries seeking to cause process disruptions.
|Loss of View||Impact||T0829||Adversaries may cause a sustained or permanent loss of view where the ICS equipment will require local, hands-on operator intervention; for instance, a restart or manual operation. By causing a sustained reporting or visibility loss, the adversary can effectively hide the present state of operations. This loss of view can occur without affecting the physical processes themselves.192021|
|Man in the Middle||Collection||T0830||Adversaries with privileged network access may seek to modify network traffic in real time using man-in-the-middle (MITM) attacks.39 This type of attack allows the adversary to intercept traffic to and/or from a particular device on the network. If a MITM attack is established, then the adversary has the ability to block, log, modify, or inject traffic into the communication stream. There are several ways to accomplish this attack, but some of the most-common are Address Resolution Protocol (ARP) poisoning and the use of a proxy.3
A MITM attack may allow an adversary to perform the following attacks:Unauthorized Command Message
|Manipulate I/O Image||Inhibit Response Function||T0835||Adversaries may manipulate the I/O image of PLCs through various means to prevent them from functioning as expected. Methods of I/O image manipulation may include overriding the I/O table via direct memory manipulation or using the override function used for testing PLC programs.40
During the PLC scan cycle, the state of the actual physical inputs is copied to a portion of the PLC memory, commonly called the input image table. When the program is scanned, it examines the input image table to read the state of a physical input.
When the logic determines the state of a physical output, it writes to a portion of the PLC memory commonly called the output image table. The output image may also be examined during the program scan. To update the physical outputs, the output image table contents are copied to the physical outputs after the program is scanned.One of the unique characteristics of PLCs is their ability to override the status of a physical discrete input or to override the logic driving a physical output coil and force the output to a desired status.
|Manipulation of Control||Impact||T0831||Adversaries may manipulate physical process control within the industrial environment. Methods of manipulating control can include changes to set point values, tags, or other parameters. Adversaries may manipulate control systems devices or possibly leverage their own, to communicate with and command physical control processes. The duration of manipulation may be temporary or longer sustained, depending on operator detection.
Methods of Manipulation of Control include:
|Manipulation of View||Impact||T0832||Adversaries may attempt to manipulate the information reported back to operators or controllers. This manipulation may be short term or sustained. During this time the process itself could be in a much different state than what is reported.192021 Operators may be fooled into doing something that is harmful to the system in a loss of view situation. With a manipulated view into the systems, operators may issue inappropriate control sequences that introduce faults or catastrophic failures into the system. Business analysis systems can also be provided with inaccurate data leading to bad management decisions.|
|Masquerading||Evasion||T0849||Adversaries may use masquerading to disguise a malicious application or executable as another file, to avoid operator and engineer suspicion. Possible disguises of these masquerading files can include commonly found programs, expected vendor executables and configuration files, and other commonplace application and naming conventions. By impersonating expected and vendor-relevant files and applications, operators and engineers may not notice the presence of the underlying malicious content and possibly end up running those masquerading as legitimate functions. Applications and other files commonly found on Windows systems or in engineering workstations have been impersonated before. This can be as simple as renaming a file to effectively disguise it in the ICS environment.|
|Modify Alarm Settings||Inhibit Response Function||T0838||Adversaries may modify alarm settings to prevent alerts that may inform operators of their presence or to prevent responses to dangerous and unintended scenarios. Reporting messages are a standard part of data acquisition in control systems. Reporting messages are used as a way to transmit system state information and acknowledgements that specific actions have occurred. These messages provide vital information for the management of a physical process, and keep operators, engineers, and administrators aware of the state of system devices and physical processes.
If an adversary is able to change the reporting settings, certain events could be prevented from being reported. This type of modification can also prevent operators or devices from performing actions to keep the system in a safe state. If critical reporting messages cannot trigger these actions then a Impact could occur.
In ICS environments, the adversary may have to use Alarm Suppression or contend with multiple alarms and/or alarm propagation to achieve a specific goal to evade detection or prevent intended responses from occurring.2 Methods of suppression often rely on modification of alarm settings, such as modifying in memory code to fixed values or tampering with assembly level instruction code.In the Maroochy Attack, the adversary disabled alarms at four pumping stations. This caused alarms to not be reported to the central computer.1
|Modify Controller Tasking||Execution||T0821||Adversaries may modify the tasking of a controller to allow for the execution of their own programs. This can allow an adversary to manipulate the execution flow and behavior of a controller.
According to 61131-3, the association of a Task with a Program Organization Unit (POU) defines a task association.41 An adversary may modify these associations or create new ones to manipulate the execution flow of a controller. Modification of controller tasking can be accomplished using a Program Download in addition to other types of program modification such as online edit and program append.Tasks have properties, such as interval, frequency and priority to meet the requirements of program execution. Some controller vendors implement tasks with implicit, pre-defined properties whereas others allow for these properties to be formulated explicitly. An adversary may associate their program with tasks that have a higher priority or execute associated programs more frequently. For instance, to ensure cyclic execution of their program on a Siemens controller, an adversary may add their program to the “task”, Organization Block 1 (OB1).
|Modify Parameter||Impair Process Control||T0836||Adversaries may modify parameters used to instruct industrial control system devices. These devices operate via programs that dictate how and when to perform actions based on such parameters. Such parameters can determine the extent to which an action is performed and may specify additional options. For example, a program on a control system device dictating motor processes may take a parameter defining the total number of seconds to run that motor.
An adversary can potentially modify these parameters to produce an outcome outside of what was intended by the operators. By modifying system and process critical parameters, the adversary may cause Impact to equipment and/or control processes. Modified parameters may be turned into dangerous, out-of-bounds, or unexpected values from typical operations. For example, specifying that a process run for more or less time than it should, or dictating an unusually high, low, or invalid value as a parameter.In the Maroochy Attack, Vitek Boden gained remote computer access to the control system and altered data so that whatever function should have occurred at affected pumping stations did not occur or occurred in a different way. The software program installed in the laptop was one developed by Hunter Watertech for its use in changing configurations in the PDS computers. This ultimately led to 800,000 liters of raw sewage being spilled out into the community.1
|Modify Program||Persistence||T0889||Adversaries may modify or add a program on a controller to affect how it interacts with the physical process, peripheral devices and other hosts on the network. Modification to controller programs can be accomplished using a Program Download in addition to other types of program modification such as online edit and program append.
Program modification encompasses the addition and modification of instructions and logic contained in Program Organization Units (POU) 41 and similar programming elements found on controllers. This can include, for example, adding new functions to a controller, modifying the logic in existing functions and making new calls from one function to another.Some programs may allow an adversary to interact directly with the native API of the controller to take advantage of obscure features or vulnerabilities.
Impair Process Control
|T0839||Adversaries may install malicious or vulnerable firmware onto modular hardware devices. Control system devices often contain modular hardware devices. These devices may have their own set of firmware that is separate from the firmware of the main control system equipment.
This technique is similar to System Firmware, but is conducted on other system components that may not have the same capabilities or level of integrity checking. Although it results in a device re-image, malicious device firmware may provide persistent access to remaining devices.42
An easy point of access for an adversary is the Ethernet card, which may have its own CPU, RAM, and operating system. The adversary may attack and likely exploit the computer on an Ethernet card. Exploitation of the Ethernet card computer may enable the adversary to accomplish additional attacks, such as the following:42
|Monitor Process State||Collection||T0801||Adversaries may gather information about the physical process state. This information may be used to gain more information about the process itself or used as a trigger for malicious actions. The sources of process state information may vary such as, OPC tags, historian data, specific PLC block information, or network traffic.|
|Native API||Execution||T0834||Adversaries may directly interact with the native OS application programming interface (API) to access system functions. Native APIs provide a controlled means of calling low-level OS services within the kernel, such as those involving hardware/devices, memory, and processes.43 These native APIs are leveraged by the OS during system boot (when other system components are not yet initialized) as well as carrying out tasks and requests during routine operations. Functionality provided by native APIs are often also exposed to user-mode applications via interfaces and libraries. For example, functions such as memcpy and direct operations on memory registers can be used to modify user and system memory space.|
|Network Connection Enumeration||Discovery||T0840||Adversaries may perform network connection enumeration to discover information about device communication patterns. If an adversary can inspect the state of a network connection with tools, such as netstat, in conjunction with System Firmware, then they can determine the role of certain devices on the network 44. The adversary can also use Network Sniffing to watch network traffic for details about the source, destination, protocol, and content.|
|Network Sniffing||Discovery||T0842||Network sniffing is the practice of using a network interface on a computer system to monitor or capture information45 regardless of whether it is the specified destination for the information.
An adversary may attempt to sniff the traffic to gain information about the target. This information can vary in the level of importance. Relatively unimportant information is general communications to and from machines. Relatively important information would be login information. User credentials may be sent over an unencrypted protocol, such as Telnet, that can be captured and obtained through network packet analysis.In addition, ARP and Domain Name Service (DNS) poisoning can be used to capture credentials to websites, proxies, and internal systems by redirecting traffic to an adversary.
|Point & Tag Identification||Collection||T0861||Adversaries may collect point and tag values to gain a more comprehensive understanding of the process environment. Points may be values such as inputs, memory locations, outputs or other process specific variables.46 Tags are the identifiers given to points for operator convenience. Collecting such tags provides valuable context to environmental points and enables an adversary to map inputs, outputs, and other values to their control processes. Understanding the points being collected may inform an adversary on which processes and values to keep track of over the course of an operation.|
|Program Download||Lateral Movement||T0843||Adversaries may perform a program download to transfer a user program to a controller.
Variations of program download, such as online edit and program append, allow a controller to continue running during the transfer and reconfiguration process without interruption to process control. However, before starting a full program download (i.e., download all) a controller may need to go into a stop state. This can have negative consequences on the physical process, especially if the controller is not able to fulfill a time-sensitive action. Adversaries may choose to avoid a download all in favor of an online edit or program append to avoid disrupting the physical process. An adversary may need to use the technique Detect Operating Mode or Change Operating Mode to make sure the controller is in the proper mode to accept a program download.
The granularity of control to transfer a user program in whole or parts is dictated by the management protocol (e.g., S7CommPlus, TriStation) and underlying controller API. Thus, program download is a high-level term for the suite of vendor-specific API calls used to configure a controller’s user program memory space.Modify Controller Tasking and Modify Program represent the configuration changes that are transferred to a controller via a program download.
|Program Upload||Collection||T0845||Adversaries may attempt to upload a program from a PLC to gather information about an industrial process. Uploading a program may allow them to acquire and study the underlying logic. Methods of program upload include vendor software, which enables the user to upload and read a program running on a PLC. This software can be used to upload the target program to a workstation, jump box, or an interfacing device.|
|Project File Infection||Persistence||T0873||Adversaries may attempt to infect project files with malicious code. These project files may consist of objects, program organization units, variables such as tags, documentation, and other configurations needed for PLC programs to function.47 Using built in functions of the engineering software, adversaries may be able to download an infected program to a PLC in the operating environment enabling further execution and persistence techniques.48 Adversaries may export their own code into project files with conditions to execute at specific intervals.32 Malicious programs allow adversaries control of all aspects of the process enabled by the PLC. Once the project file is downloaded to a PLC the workstation device may be disconnected with the infected project file still executing.48|
|Remote Services||Lateral Movement|
|T0886||Adversaries may leverage remote services to move between assets and network segments. These services are often used to allow operators to interact with systems remotely within the network, some examples are RDP, SMB, SSH, and other similar mechanisms.495029
Remote services could be used to support remote access, data transmission, authentication, name resolution, and other remote functions. Further, remote services may be necessary to allow operators and administrators to configure systems within the network from their engineering or management workstations. An adversary may use this technique to access devices which may be dual-homed49 to multiple network segments, and can be used for Program Download or to execute attacks on control devices directly through Valid Accounts.Specific remote services (RDP & VNC) may be a precursor to enable Graphical User Interface execution on devices such as HMIs or engineering workstation software.
|Remote System Discovery||Discovery||T0846||Adversaries may attempt to get a listing of other systems by IP address, hostname, or other logical identifier on a network that may be used for subsequent Lateral Movement or Discovery techniques. Functionality could exist within adversary tools to enable this, but utilities available on the operating system or vendor software could also be used.51|
|Remote System Information Discovery||Discovery||T0888||An adversary may attempt to get detailed information about remote systems and their peripherals, such as make/model, role, and configuration. Adversaries may use information from Remote System Information Discovery to aid in targeting and shaping follow-on behaviors. For example, the system’s operational role and model information can dictate whether it is a relevant target for the adversary’s operational objectives. In addition, the system’s configuration may be used to scope subsequent technique usage. Requests for system information are typically implemented using automation and management protocols and are often automatically requested by vendor software during normal operation. This information may be used to tailor management actions, such as program download and system or module firmware. An adversary may leverage this same information by issuing calls directly to the system’s API.|
|Replication Through Removable Media||Initial Access||T0847||Adversaries may move onto systems, such as those separated from the enterprise network, by copying malware to removable media which is inserted into the control systems environment. The adversary may rely on unknowing trusted third parties, such as suppliers or contractors with access privileges, to introduce the removable media. This technique enables initial access to target devices that never connect to untrusted networks, but are physically accessible. Operators of the German nuclear power plant, Gundremmingen, discovered malware on a facility computer not connected to the internet.5253 The malware included Conficker and W32.Ramnit, which were also found on eighteen removable disk drives in the facility.545556575859 The plant has since checked for infection and cleaned up more than 1,000 computers.60 An ESET researcher commented that internet disconnection does not guarantee system safety from infection or payload execution.61|
|Rogue Master||Initial Access||T0848||Adversaries may setup a rogue master to leverage control server functions to communicate with outstations. A rogue master can be used to send legitimate control messages to other control system devices, affecting processes in unintended ways. It may also be used to disrupt network communications by capturing and receiving the network traffic meant for the actual master. Impersonating a master may also allow an adversary to avoid detection.
In the Maroochy Attack, Vitek Boden falsified network addresses in order to send false data and instructions to pumping stations.1In the case of the 2017 Dallas Siren incident, adversaries used a rogue master to send command messages to the 156 distributed sirens across the city, either through a single rogue transmitter with a strong signal, or using many distributed repeaters.6263
Inhibit Response Function
|T0851||Adversaries may deploy rootkits to hide the presence of programs, files, network connections, services, drivers, and other system components. Rootkits are programs that hide the existence of malware by intercepting and modifying operating-system API calls that supply system information. Rootkits or rootkit-enabling functionality may reside at the user or kernel level in the operating system, or lower.64 Firmware rootkits that affect the operating system yield nearly full control of the system. While firmware rootkits are normally developed for the main processing board, they can also be developed for I/O that can be attached to the asset. Compromise of this firmware allows the modification of all of the process variables and functions the module engages in. This may result in commands being disregarded and false information being fed to the main device. By tampering with device processes, an adversary may inhibit its expected response functions and possibly enable Impact.|
|Screen Capture||Collection||T0852||Adversaries may attempt to perform screen capture of devices in the control system environment. Screenshots may be taken of workstations, HMIs, or other devices that display environment-relevant process, device, reporting, alarm, or related data. These device displays may reveal information regarding the ICS process, layout, control, and related schematics. In particular, an HMI can provide a lot of important industrial process information.65 Analysis of screen captures may provide the adversary with an understanding of intended operations and interactions between critical devices.|
|Scripting||Execution||T0853||Adversaries may use scripting languages to execute arbitrary code in the form of a pre-written script or in the form of user-supplied code to an interpreter. Scripting languages are programming languages that differ from compiled languages, in that scripting languages use an interpreter, instead of a compiler. These interpreters read and compile part of the source code just before it is executed, as opposed to compilers, which compile each and every line of code to an executable file. Scripting allows software developers to run their code on any system where the interpreter exists. This way, they can distribute one package, instead of precompiling executables for many different systems. Scripting languages, such as Python, have their interpreters shipped as a default with many Linux distributions. In addition to being a useful tool for developers and administrators, scripting language interpreters may be abused by the adversary to execute code in the target environment. Due to the nature of scripting languages, this allows for weaponized code to be deployed to a target easily, and leaves open the possibility of on-the-fly scripting to perform a task.|
|Service Stop||Inhibit Response Function||T0881||Adversaries may stop or disable services on a system to render those services unavailable to legitimate users. Stopping critical services can inhibit or stop response to an incident or aid in the adversary's overall objectives to cause damage to the environment.66 Services may not allow for modification of their data stores while running. Adversaries may stop services in order to conduct Data Destruction.66|
|Spearphishing Attachment||Initial Access||T0865||Adversaries may use a spearphishing attachment, a variant of spearphishing, as a form of a social engineering attack against specific targets. Spearphishing attachments are different from other forms of spearphishing in that they employ malware attached to an email. All forms of spearphishing are electronically delivered and target a specific individual, company, or industry. In this scenario, adversaries attach a file to the spearphishing email and usually rely upon User Execution to gain execution and access.67|
|Spoof Reporting Message||Evasion|
Impair Process Control
|T0856||Adversaries may spoof reporting messages in control system environments for evasion and to impair process control. In control systems, reporting messages contain telemetry data (e.g., I/O values) pertaining to the current state of equipment and the industrial process. Reporting messages are important for monitoring the normal operation of a system or identifying important events such as deviations from expected values.
If an adversary has the ability to Spoof Reporting Messages, they can impact the control system in many ways. The adversary can Spoof Reporting Messages that state that the process is operating normally, as a form of evasion. The adversary could also Spoof Reporting Messages to make the defenders and operators think that other errors are occurring in order to distract them from the actual source of a problem.3In the Maroochy Attack, the adversary used a dedicated analog two-way radio system to send false data and instructions to pumping stations and the central computer.1
|Standard Application Layer Protocol||Command and Control||T0869||Adversaries may establish command and control capabilities over commonly used application layer protocols such as HTTP(S), OPC, RDP, telnet, DNP3, and modbus. These protocols may be used to disguise adversary actions as benign network traffic. Standard protocols may be seen on their associated port or in some cases over a non-standard port. Adversaries may use these protocols to reach out of the network for command and control, or in some cases to other infected devices within the network.|
|Supply Chain Compromise||Initial Access||T0862||Adversaries may perform supply chain compromise to gain control systems environment access by means of infected products, software, and workflows. Supply chain compromise is the manipulation of products, such as devices or software, or their delivery mechanisms before receipt by the end consumer. Adversary compromise of these products and mechanisms is done for the goal of data or system compromise, once infected products are introduced to the target environment.
Supply chain compromise can occur at all stages of the supply chain, from manipulation of development tools and environments to manipulation of developed products and tools distribution mechanisms. This may involve the compromise and replacement of legitimate software and patches, such as on third party or vendor websites. Targeting of supply chain compromise can be done in attempts to infiltrate the environments of a specific audience. In control systems environments with assets in both the IT and OT networks, it is possible a supply chain compromise affecting the IT environment could enable further access to the OT environment.
Counterfeit devices may be introduced to the global supply chain posing safety and cyber risks to asset owners and operators. These devices may not meet the safety, engineering and manufacturing requirements of regulatory bodies but may feature tagging indicating conformance with industry standards. Due to the lack of adherence to standards and overall lesser quality, the counterfeit products may pose a serious safety and operational risk.68
Yokogawa identified instances in which their customers received counterfeit differential pressure transmitters using the Yokogawa logo. The counterfeit transmitters were nearly indistinguishable with a semblance of functionality and interface that mimics the genuine product.68F-Secure Labs analyzed the approach the adversary used to compromise victim systems with Havex.69 The adversary planted trojanized software installers available on legitimate ICS/SCADA vendor websites. After being downloaded, this software infected the host computer with a Remote Access Trojan (RAT).
Inhibit Response Function
|T0857||System firmware on modern assets is often designed with an update feature. Older device firmware may be factory installed and require special reprograming equipment. When available, the firmware update feature enables vendors to remotely patch bugs and perform upgrades. Device firmware updates are often delegated to the user and may be done using a software update package. It may also be possible to perform this task over the network. An adversary may exploit the firmware update feature on accessible devices to upload malicious or out-of-date firmware. Malicious modification of device firmware may provide an adversary with root access to a device, given firmware is one of the lowest programming abstraction layers.70|
|Theft of Operational Information||Impact||T0882||Adversaries may steal operational information on a production environment as a direct mission outcome for personal gain or to inform future operations. This information may include design documents, schedules, rotational data, or similar artifacts that provide insight on operations. In the Bowman Dam incident, adversaries probed systems for operational data.3635|
|Unauthorized Command Message||Impair Process Control||T0855||Adversaries may send unauthorized command messages to instruct control system assets to perform actions outside of their intended functionality, or without the logical preconditions to trigger their expected function. Command messages are used in ICS networks to give direct instructions to control systems devices. If an adversary can send an unauthorized command message to a control system, then it can instruct the control systems device to perform an action outside the normal bounds of the device's actions. An adversary could potentially instruct a control systems device to perform an action that will cause an Impact.3
In the Maroochy Attack, the adversary used a dedicated analog two-way radio system to send false data and instructions to pumping stations and the central computer.1In the Dallas Siren incident, adversaries were able to send command messages to activate tornado alarm systems across the city without an impending tornado or other disaster. Alarms were activated more than a dozen times.6371 These disruptions occurred once in 2017, and later in a nearby county in 2019.71
|User Execution||Execution||T0863||Adversaries may rely on a targeted organizations’ user interaction for the execution of malicious code. User interaction may consist of installing applications, opening email attachments, or granting higher permissions to documents. Adversaries may embed malicious code or visual basic code into files such as Microsoft Word and Excel documents or software installers.72 Execution of this code requires that the user enable scripting or write access within the document. Embedded code may not always be noticeable to the user especially in cases of trojanized software.73|
|T0859||Adversaries may steal the credentials of a specific user or service account using credential access techniques. In some cases, default credentials for control system devices may be publicly available. Compromised credentials may be used to bypass access controls placed on various resources on hosts and within the network, and may even be used for persistent access to remote systems. Compromised and default credentials may also grant an adversary increased privilege to specific systems and devices or access to restricted areas of the network. Adversaries may choose not to use malware or tools, in conjunction with the legitimate access those credentials provide, to make it harder to detect their presence or to control devices and send legitimate commands in an unintended way.
Adversaries may also create accounts, sometimes using predefined account names and passwords, to provide a means of backup access for persistence.72The overlap of credentials and permissions across a network of systems is of concern because the adversary may be able to pivot across accounts and systems to reach a high level of access (i.e., domain or enterprise administrator) and possibly between the enterprise and operational technology environments. Adversaries may be able to leverage valid credentials from one system to gain access to another system.
|Wireless Compromise||Initial Access||T0860||Adversaries may perform wireless compromise as a method of gaining communications and unauthorized access to a wireless network. Access to a wireless network may be gained through the compromise of a wireless device.7475 Adversaries may also utilize radios and other wireless communication devices on the same frequency as the wireless network. Wireless compromise can be done as an initial access vector from a remote distance.
A joint case study on the Maroochy Shire Water Services event examined the attack from a cyber security perspective.1 The adversary disrupted Maroochy Shire's radio-controlled sewage system by driving around with stolen radio equipment and issuing commands with them. Boden used a two-way radio to communicate with and set the frequencies of Maroochy Shire's repeater stations.A Polish student used a modified TV remote controller to gain access to and control over the Lodz city tram system in Poland.1213 The remote controller device allowed the student to interface with the tram’s network to modify track settings and override operator control. The adversary may have accomplished this by aligning the controller to the frequency and amplitude of IR control protocol signals.14 The controller then enabled initial access to the network, allowing the capture and replay of tram signals.12
|T0887||Adversaries may seek to capture radio frequency (RF) communication used for remote control and reporting in distributed environments. RF communication frequencies vary between 3 kHz to 300 GHz, although are commonly between 300 MHz to 6 GHz.76 The wavelength and frequency of the signal affect how the signal propagates through open air, obstacles (e.g. walls and trees) and the type of radio required to capture them. These characteristics are often standardized in the protocol and hardware and may have an effect on how the signal is captured. Some examples of wireless protocols that may be found in cyber-physical environments are: WirelessHART, Zigbee, WIA-FA, and 700 MHz Public Safety Spectrum.
Adversaries may capture RF communications by using specialized hardware, such as software defined radio (SDR), handheld radio, or a computer with radio demodulator tuned to the communication frequency.62 Information transmitted over a wireless medium may be captured in-transit whether the sniffing device is the intended destination or not. This technique may be particularly useful to an adversary when the communications are not encrypted.77In the 2017 Dallas Siren incident, it is suspected that adversaries likely captured wireless command message broadcasts on a 700 MHz frequency during a regular test of the system. These messages were later replayed to trigger the alarm systems.77
- Marshall Abrams. (2008, July 23). Malicious Control System Cyber Security Attack Case Study– Maroochy Water Services, Australia. Retrieved March 27, 2018.
- Jos Wetzels, Marina Krotofil. (2019). A Diet of Poisoned Fruit: Designing Implants & OT Payloads for ICS Embedded Devices. Retrieved November 1, 2019.
- Bonnie Zhu, Anthony Joseph, Shankar Sastry. (2011). A Taxonomy of Cyber Attacks on SCADA Systems. Retrieved January 12, 2018.
- Electricity Information Sharing and Analysis Center; SANS Industrial Control Systems. (2016, March 18). Analysis of the Cyber Attack on the Ukranian Power Grid: Defense Use Case. Retrieved March 27, 2018.
- N.A.. (2017, October). What are the different operating modes in PLC?. Retrieved January 28, 2021.
- Omron. (n.d.). PLC Different Operating Modes. Retrieved January 28, 2021.
- Machine Information Systems. (2007). How PLCs Work. Retrieved January 28, 2021.
- PLCgurus. (2021). PLC Basics – Modes Of Operation. Retrieved January 28, 2021.
- Enterprise ATT&CK. (2018, January 11). Command-Line Interface. Retrieved May 17, 2018.
- Enterprise ATT&CK. (2018, January 11). Connection Proxy. Retrieved May 17, 2018.
- Bundesamt für Sicherheit in der Informationstechnik (BSI) (German Federal Office for Information Security). (2014). Die Lage der IT-Sicherheit in Deutschland 2014 (The State of IT Security in Germany). Retrieved October 30, 2019.
- John Bill. (2017, May 12). Hacked Cyber Security Railways. Retrieved October 17, 2019.
- Shelley Smith. (2008, February 12). Teen Hacker in Poland Plays Trains and Derails City Tram System. Retrieved October 17, 2019.
- Bruce Schneier. (2008, January 17). Hacking Polish Trams. Retrieved October 17, 2019.
- Enterprise ATT&CK. (2018, January 11). File Deletion. Retrieved May 17, 2018.
- Dragos. (2018, October 12). Anatomy of an Attack: Detecting and Defeating CRASHOVERRIDE. Retrieved October 14, 2019.
- Cybersecurity & Infrastructure Security Agency. (2018, March 15). Alert (TA18-074A) Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved October 11, 2019.
- Keith Stouffer. (2015, May). Guide to Industrial Control Systems (ICS) Security. Retrieved March 28, 2018.
- Corero. (n.d.). Industrial Control System (ICS) Security. Retrieved November 4, 2019.
- Michael J. Assante and Robert M. Lee. (n.d.). The Industrial Control System Cyber Kill Chain. Retrieved November 4, 2019.
- Tyson Macaulay. (n.d.). RIoT Control: Understanding and Managing Risks and the Internet of Things. Retrieved November 4, 2019.
- Mark Loveless. (2017, April 11). THE DALLAS COUNTY SIREN HACK. Retrieved November 6, 2020.
- ICS-CERT. (2017, April 18). CS Alert (ICS-ALERT-17-102-01A) BrickerBot Permanent Denial-of-Service Attack. Retrieved October 24, 2019.
- ICS-CERT. (2018, August 27). Advisory (ICSA-15-202-01) - Siemens SIPROTEC Denial-of-Service Vulnerability. Retrieved March 14, 2019.
- Common Weakness Enumeration. (2019, January 03). CWE-400: Uncontrolled Resource Consumption. Retrieved March 14, 2019.
- MITRE. (2018, March 22). CVE-2015-5374. Retrieved March 14, 2019.
- The MITRE Corporation. (n.d.). ATT&CK T1068: Exploitation for Privilege Escalation. Retrieved April 12, 2021.
- Enterprise ATT&CK. (n.d.). Exploitation of Remote Services. Retrieved October 27, 2019.
- Joe Slowik. (2019, April 10). Implications of IT Ransomware for ICS Environments. Retrieved October 27, 2019.
- Daniel Oakley, Travis Smith, Tripwire. (n.d.). Retrieved May 30, 2018.
- Enterprise ATT&CK. (n.d.). Hooking. Retrieved October 27, 2019.
- Nicolas Falliere, Liam O Murchu, Eric Chien. (2011, February). W32.Stuxnet Dossier (Version 1.4). Retrieved September 22, 2017.
- Spenneberg, Ralf. (2016). PLC-Blaster. Retrieved June 6, 2019.
- NCCIC. (2014, January 1). Internet Accessible Control Systems At Risk. Retrieved November 7, 2019.
- Danny Yadron. (2015, December 20). Iranian Hackers Infiltrated New York Dam in 2013. Retrieved November 7, 2019.
- Mark Thompson. (2016, March 24). Iranian Cyber Attack on New York Dam Shows Future of War. Retrieved November 7, 2019.
- Stephen Hilt, Federico Maggi, Charles Perine, Lord Remorin, Martin Rösler, and Rainer Vosseler. (n.d.). Caught in the Act: Running a Realistic Factory Honeypot to Capture Real Threats. Retrieved April 12, 2021.
- Enterprise ATT&CK. (n.d.). Lateral Tool Transfer. Retrieved October 27, 2019.
- Gabriel Sanchez. (2017, October). Man-In-The-Middle Attack Against Modbus TCP Illustrated with Wireshark. Retrieved January 5, 2020.
- Dr. Kelvin T. Erickson. (2010, December). Programmable logic controller hardware. Retrieved March 29, 2018.
- IEC. (2013, February 20). IEC 61131-3:2013 Programmable controllers - Part 3: Programming languages. Retrieved October 22, 2019.
- Daniel Peck, Dale Peterson. (2009, January 28). Leveraging Ethernet Card Vulnerabilities in Field Devices. Retrieved December 19, 2017.
- The MITRE Corporation. (2017, May 31). ATT&CK T1106: Native API. Retrieved April 26, 2021.
- MITRE. (n.d.). System Network Connections Discovery. Retrieved May 31, 2018.
- Enterprise ATT&CK. (2018, January 11). Network Sniffing. Retrieved May 17, 2018.
- Benjamin Green. (n.d.). On the Significance of Process Comprehension for Conducting Targeted ICS Attacks. Retrieved November 1, 2019.
- Beckhoff. (n.d.). TwinCAT 3 Source Control: Project Files. Retrieved November 21, 2019.
- PLCdev. (n.d.). Siemens SIMATIC Step 7 Programmer's Handbook. Retrieved November 21, 2019.
- Blake Johnson, Dan Caban, Marina Krotofil, Dan Scali, Nathan Brubaker, Christopher Glyer. (2017, December 14). Attackers Deploy New ICS Attack Framework “TRITON” and Cause Operational Disruption to Critical Infrastructure. Retrieved January 12, 2018.
- Dragos. (2017, December 13). TRISIS Malware Analysis of Safety System Targeted Malware. Retrieved January 12, 2018.
- Enterprise ATT&CK. (2018, January 11). Remote System Discovery. Retrieved May 17, 2018.
- Kernkraftwerk Gundremmingen. (2016, April 25). Detektion von Büro-Schadsoftware an mehreren Rechnern. Retrieved October 14, 2019.
- Trend Micro. (2016, April 27). Malware Discovered in German Nuclear Power Plant. Retrieved October 14, 2019.
- Christoph Steitz, Eric Auchard. (2016, April 26). German nuclear plant infected with computer viruses, operator says. Retrieved October 14, 2019.
- Catalin Cimpanu. (2016, April 26). Malware Shuts Down German Nuclear Power Plant on Chernobyl's 30th Anniversary. Retrieved October 14, 2019.
- Peter Dockrill. (2016, April 28). Multiple Computer Viruses Have Been Discovered in This German Nuclear Plant. Retrieved October 14, 2019.
- Lee Mathews. (2016, April 27). German nuclear plant found riddled with Conficker, other viruses. Retrieved October 14, 2019.
- Sean Gallagher. (2016, April 27). German nuclear plant’s fuel rod system swarming with old malware. Retrieved October 14, 2019.
- Dark Reading Staff. (2016, April 28). German Nuclear Power Plant Infected With Malware. Retrieved October 14, 2019.
- BBC. (2016, April 28). German nuclear plant hit by computer viruses. Retrieved October 14, 2019.
- ESET. (2016, April 28). Malware found at a German nuclear power plant. Retrieved October 14, 2019.
- Bastille. (2017, April 17). Dallas Siren Attack. Retrieved November 6, 2020.
- Zack Whittaker. (2017, April 12). Dallas' emergency sirens were hacked with a rogue radio signal. Retrieved November 6, 2020.
- Enterprise ATT&CK. (2018, January 11). Rootkit. Retrieved May 16, 2018.
- ICS-CERT. (2017, October 21). Advanced Persistent Threat Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved October 23, 2017.
- Enterprise ATT&CK. (n.d.). Service Stop. Retrieved October 29, 2019.
- Enterprise ATT&CK. (2019, October 25). Spearphishing Attachment. Retrieved October 25, 2019.
- Control Global. (2019, May 29). Yokogawa announcement warns of counterfeit transmitters. Retrieved April 9, 2021.
- F-Secure Labs. (2014, June 23). Havex Hunts For ICS/SCADA Systems. Retrieved October 21, 2019.
- Basnight, Zachry, et al.. (n.d.). Retrieved October 17, 2017.
- Benjamin Freed. (2019, March 13). Tornado sirens in Dallas suburbs deactivated after being hacked and set off. Retrieved November 6, 2020.
- Booz Allen Hamilton. (n.d.). When The Lights Went Out. Retrieved October 22, 2019.
- Daavid Hentunen, Antti Tikkanen. (2014, June 23). Havex Hunts For ICS/SCADA Systems. Retrieved April 1, 2019.
- Alexander Bolshev, Gleb Cherbov. (2014, July 08). ICSCorsair: How I will PWN your ERP through 4-20 mA current loop. Retrieved January 5, 2020.
- Alexander Bolshev. (2014, March 11). S4x14: HART As An Attack Vector. Retrieved January 5, 2020.
- Candell, R., Hany, M., Lee, K. B., Liu,Y., Quimby, J., Remley, K.. (2018, April). Guide to Industrial Wireless Systems Deployments. Retrieved December 1, 2020.
- Gallagher, S.. (2017, April 12). Pirate radio: Signal spoof set off Dallas emergency sirens, not network hack. Retrieved December 1, 2020.