Below is a list of all 81 techniques in ATT&CK for ICS:
|Activate Firmware Update Mode||Inhibit Response Function||T800||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||T878||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||T802||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||T803||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.3 In the 2015 attack on the Ukranian power grid, malicious firmware was used to render communication devices inoperable and effectively prevent them from receiving remote command messages.4|
|Block Reporting Message||Inhibit Response Function||T804||Adversaries may block or prevent a reporting message from reaching its intended target. Reporting messages relay the status of control system devices, which can include event log data and I/O values of the associated device. 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.3In the 2015 attack on the Ukranian power grid, malicious firmware was used to render communication devices inoperable and effectively block messages from being reported.4
|Block Serial COM||Inhibit Response Function||T805||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||T806||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 Program State||Execution|
Impair Process Control
|T875||Adversaries may attempt to change the state of the current program on a control device. Program state changes may be used to allow for another program to take over control or be loaded onto the device.|
|Command-Line Interface||Execution||T807||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.5 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||T885||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||T884||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.6
|Control Device Identification||Discovery||T808||Adversaries may perform control device identification to determine the make and model of a target device. Management software and device APIs may be utilized by the adversary to gain this information. By identifying and obtaining device specifics, the adversary may be able to determine device vulnerabilities. This device information can also be used to understand device functionality and inform the decision to target the environment.|
|Damage to Property||Impact||T879||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.7 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.8910 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.9 Commands issued by the student may have also resulted in tram collisions, causing harm to those on board and the environment outside.10
|Data Destruction||Inhibit Response Function||T809||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.11
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||T810||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.12 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||T811||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 target information repositories include reference databases and local machines on the process environment.|
|Default Credentials||Lateral Movement||T812||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.13 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||T813||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.141516 In the Maroochy attack, the adversary was able to temporarily shut an investigator out of the network preventing them from issuing any controls.|
|Denial of Service||Inhibit Response Function||T814||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.17
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 Control Device Identification. There are examples of adversaries remotely causing a Device Restart/Shutdown by exploiting a vulnerability that induces uncontrolled resource consumption.181920In the Maroochy attack, the adversary was able to shut an investigator out of the network.1
|Denial of View||Impact||T815||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.141516
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||T868||Adversaries may gather information about the current operating state of a PLC. CPU operating modes are often controlled by a key switch on the PLC. Example states may be run, prog, stop, remote, and invalid. Knowledge of these states may be valuable to an adversary to determine if they are able to reprogram the PLC.|
|Detect Program State||Collection||T870||Adversaries may seek to gather information about the current state of a program on a PLC. State information reveals information about the program, including whether it's running, halted, stopped, or has generated an exception. This information may be leveraged as a verification of malicious program execution or to determine if a PLC is ready to download a new program.|
|Device Restart/Shutdown||Inhibit Response Function||T816||Adversaries may forcibly restart or shutdown a device in the ICS environment to disrupt and potentially cause adverse effects on the physical processes it helps to control. Methods of device restart and shutdown exist as built-in, standard functionalities. This can include interactive device web interfaces, CLIs, and network protocol commands, among others. Device restart or shutdown may also occur as a consequence of changing a device into an alternative mode of operation for testing or firmware loading.
Unexpected restart or shutdown of control system devices may contribute to impact, by preventing expected response functions from activating and being received in critical states. This can also be a sign of malicious device modification, as many updates require a shutdown in order to take affect.3
For example, DNP3's function code 0x0D can reset and reconfigure DNP3 outstations by forcing them to perform a complete power cycle.3In the 2015 attack on the Ukranian power grid, the adversaries gained access to the control networks of three different energy companies. The adversaries scheduled disconnects for the uniterruptable power supply (UPS) systems so that when power was disconnected from the substations, the devices would shut down and service could not be recovered.4
|Drive-by Compromise||Initial Access||T817||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.21 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||T818||Adversaries may compromise and gain control of an engineering workstation as an Initial Access technique into the control system environment. Access to an engineering workstation may occur as a result of remote access or by physical means, such as a person 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.
|Execution through API||Execution||T871||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, such as Change Program State of a program on a PLC.|
|Exploit Public-Facing Application||Initial Access||T819||Adversaries may attempt to exploit public-facing applications to leverage weaknesses on Internet-facing computer systems, programs, or assets in order to cause unintended or unexpected behavior. These public-facing applications may include user interfaces, software, data, or commands. In particular, a public-facing application in the IT environment may provide adversaries an interface into the OT environment. ICS-CERT analysis has identified the probable initial infection vector for systems running GE’s Cimplicity HMI with a direct connection to the Internet.22|
|Exploitation for Evasion||Evasion||T820||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 Control Device Identification 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 of Remote Services||Lateral Movement||T866||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 lateral movement to enable access to a remote system.23 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.24|
|External Remote Services||Lateral Movement|
|T822||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.25
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.4
In the Maroochy Attack, the adversary was able to gain remote computer access to the system over radio.The 2015 attack on the Ukranian power grid showed the use of existing remote access tools within the environment to access the control system network. The adversary harvested worker credentials, some of them for VPNs the grid workers used to remotely log into the control system networks.2642728 The VPNs into these networks appear to have lacked two‐factor authentication.4
|Graphical User Interface||Execution||T823||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.In the 2015 attack on the Ukrainian power grid, the adversary utilized the GUI of HMIs in the SCADA environment to open breakers.4
|Hooking||Persistence||T874||Adversaries may hook into application programming interface (API) functions used by processes to redirect calls for persistent 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.29 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.30|
|I/O Image||Collection||T877||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.31|
|I/O Module Discovery||Discovery||T824||Adversaries may use input/output (I/O) module discovery to gather key information about a control system device. An I/O module is a device that allows the control system device to either receive or send signals to other devices. These signals can be analog or digital, and may support a number of different protocols. Devices are often able to use attachable I/O modules to increase the number of inputs and outputs that it can utilize. An adversary with access to a device can use native device functions to enumerate I/O modules that are connected to the device. Information regarding the I/O modules can aid the adversary in understanding related control processes.|
|Indicator Removal on Host||Evasion||T872||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||T883||Adversaries may gain access into industrial environments directly through systems exposed to the internet for remote access rather than through External Remote Services. Minimal protections provided by these devices such as password authentication may be targeted and compromised.32 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. 333432|
|Location Identification||Collection||T825||Adversaries may perform location identification using device data to inform operations and targeted impact for attacks. Location identification data can come in a number of forms, including geographic location, location relative to other control system devices, time zone, and current time. An adversary may use an embedded global positioning system (GPS) module in a device to figure out the physical coordinates of a device. NIST SP800-82 recommends that devices utilize GPS or another location determining mechanism to attach appropriate timestamps to log entries13. While this assists in logging and event tracking, an adversary could use the underlying positioning mechanism to determine the general location of a device. An adversary can also infer the physical location of serially connected devices by using serial connection enumeration. An adversary attempt to attack and cause Impact could potentially affect other control system devices in close proximity. Device local-time and time-zone settings can also provide adversaries a rough indicator of device location, when specific geographic identifiers cannot be determined from the system.|
|Loss of Availability||Impact||T826||Adversaries may attempt to disrupt essential components or systems to prevent owner and operator from delivering products or services.141516 Adversaries may leverage malware to delete or encrypt critical data on HMIs, workstations, or databases.|
|Loss of Control||Impact||T827||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.141516|
|Loss of Productivity and Revenue||Impact||T828||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 Safety||Impact||T880||Adversaries may cause loss of safety whether on purpose or as a consequence of actions taken to accomplish an operation. The loss of safety can describe a physical impact and threat, or the potential for unsafe conditions and activity in terms of control systems environments, devices, or processes. For instance, an adversary may issue commands or influence and possibly inhibit safety mechanisms that allow the injury of and possible loss of life. This can also encompass scenarios resulting in the failure of a safety mechanism or control, that may lead to unsafe and dangerous execution and outcomes of physical processes and related systems.141516
The German Federal Office for Information Security (BSI) reported a targeted attack on a steel mill in its 2014 IT Security Report.7 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.A Polish student used a remote controller device to interface with the Lodz city tram system in Poland.8910 Using this remote, the student was able to capture and replay legitimate tram signals. As a consequence, four trams were derailed and twelve people injured due to resulting emergency stops.9 The track controlling commands issued may have also resulted in tram collisions, a further risk to those on board and nearby the areas of impact.10
|Loss of View||Impact||T829||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.141516|
|Man in the Middle||Execution||T830||Adversaries with privileged network access may seek to modify network traffic in real time using man-in-the-middle (MITM) attacks.35 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:Spoof Reporting Message
|Manipulate I/O Image||Inhibit Response Function||T835||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.36
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||T831||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||T832||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.141516 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.|
Impair Process Control
|T849||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||T838||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 Control Logic||Impair Process Control|
Inhibit Response Function
|T833||Adversaries may place malicious code in a system, which can cause the system to malfunction by modifying its control logic. Control system devices use programming languages (e.g. relay ladder logic) to control physical processes by affecting actuators, which cause machines to operate, based on environment sensor readings. These devices often include the ability to perform remote control logic updates.
Program code is normally edited in a vendor-specific Integrated Development Environment (IDE) that relies on proprietary tools and features. These IDEs allow an engineer to perform host target development and may have the ability to run the code on the machine it is programmed for. The IDE will transmit the control logic to the testing device, and will perform the required device-specific functions to apply the changes and make them active.
An adversary may attempt to use this host target IDE to modify device control logic. Even though proprietary tools are often used to edit and update control logic, the process can usually be reverse-engineered and reproduced with open-source tools.
An adversary can de-calibrate a sensor by removing functions in control logic that account for sensor error. This can be used to change a control process without actually spoofing command messages to a controller or device.
It is believed this process happened in the lesser known over-pressurizer attacks build into Stuxnet. Pressure sensors are not perfect at translating pressure into an analog output signal, but their errors can be corrected by calibration. The pressure controller can be told what the “real” pressure is for given analog signals and then automatically linearize the measurement to what would be the “real” pressure. If the linearization is overwritten by malicious code on the S7-417 controller, analog pressure readings will be “corrected” during the attack by the pressure controller, which then interprets all analog pressure readings as perfectly normal pressure no matter how high or low their analog values are. The pressure controller then acts accordingly by never opening the stage exhaust valves. In the meantime, actual pressure keeps rising.37In 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 Parameter||Impair Process Control||T836||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
Impair Process Control
|T839||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.38
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:38
|Monitor Process State||Collection||T801||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.|
|Network Connection Enumeration||Discovery||T840||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 39. The adversary can also use Network Sniffing to watch network traffic for details about the source, destination, protocol, and content.|
|Network Service Scanning||Discovery||T841||Network Service Scanning is the process of discovering services on networked systems. This can be achieved through a technique called port scanning or probing. Port scanning interacts with the TCP/IP ports on a target system to determine whether ports are open, closed, or filtered by a firewall. This does not reveal the service that is running behind the port, but since many common services are run on specific port numbers, the type of service can be assumed. More in-depth testing includes interaction with the actual service to determine the service type and specific version. One of the most-popular tools to use for Network Service Scanning is Nmap.
An adversary may attempt to gain information about a target device and its role on the network via Network Service Scanning techniques, such as port scanning. Network Service Scanning is useful for determining potential vulnerabilities in services on target devices. Network Service Scanning is closely tied to .Scanning ports can be noisy on a network. In some attacks, adversaries probe for specific ports using custom tools. This was specifically seen in the Triton and PLC-Blaster attacks.
|Network Sniffing||Discovery||T842||Network sniffing is the practice of using a network interface on a computer system to monitor or capture information40 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. Network sniffing can be a way to discover information for Control Device Identification.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||T861||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.41 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.|
Impair Process Control
Inhibit Response Function
|T843||Adversaries may perform a program download to load malicious or unintended program logic on a device as a method of persistence or to disrupt response functions or process control. Program download onto devices, such as PLCs, allows adversaries to implement custom logic. Malicious PLC programs may be used to disrupt physical processes or enable adversary persistence. The act of a program download will cause the PLC to enter a STOP operation state, which may prevent response functions from operating correctly.|
|Program Organization Units||Lateral Movement|
|T844||Program Organizational Units (POUs) are block structures used within PLC programming to create programs and projects.42 POUs can be used to hold user programs written in IEC 61131-3 languages: Structured text, Instruction list, Function block, and Ladder logic.43 They can also provide additional functionality, such as establishing connections between the PLC and other devices using TCON.44
Stuxnet uses a simple code-prepending infection technique to infect Organization Blocks (OB). For example, the following sequence of actions is performed when OB1 is infected 30:
|Program Upload||Collection||T845||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|
|T873||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.45 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.46 Adversaries may export their own code into project files with conditions to execute at specific intervals.30 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.46|
|Remote File Copy||Lateral Movement||T867||Adversaries may copy files from one system to another to stage adversary tools or other files over the course of an operation.47 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.47 In control systems environments, malware may use SMB and other file sharing protocols to move laterally through industrial networks.|
|Remote System Discovery||Discovery||T846||Remote System Discovery is the process of identifying the presence of hosts on a network48, and details about them. This process is common to network administrators validating the presence of machines and services, as well as adversaries mapping out a network for future-attack targets. An adversary may attempt to gain information about the target network via network enumeration techniques such as port scanning. One of the most popular tools for enumeration is Nmap. Remote System Discovery allows adversaries to map out hosts on the network as well as the TCP/IP ports that are open, closed, or filtered. Remote System Discovery tools also aid in by attempting to connect to the service and determine its exact version. The adversary may use this information to pick an exploit for a particular version if a known vulnerability exists.|
|Replication Through Removable Media||Initial Access||T847||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.4950 The malware included Conficker and W32.Ramnit, which were also found on eighteen removable disk drives in the facility.515253545556 The plant has since checked for infection and cleaned up more than 1,000 computers.57 An ESET researcher commented that internet disconnection does not guarantee system safety from infection or payload execution.58|
|Rogue Master Device||Evasion|
Impair Process Control
|T848||Adversaries may setup a rogue master to leverage control server functions to communicate with slave devices. A rogue master device 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 device. Impersonating a master device 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.1|
|Role Identification||Collection||T850||Adversaries may perform role identification of devices involved with physical processes of interest in a target control system. Control systems devices often work in concert to control a physical process. Each device can have one or more roles that it performs within that control process. By collecting this role-based data, an adversary can construct a more targeted attack. For example, a power generation plant may have unique devices such as one that monitors power output of a generator and another that controls the speed of a turbine. Examining devices roles allows the adversary to observe how the two devices work together to monitor and control a physical process. Understanding the role of a target device can inform the adversary's decision on what action to take, in order to cause Impact and influence or disrupt the integrity of operations. Furthermore, an adversary may be able to capture control system protocol traffic. By studying this traffic, the adversary may be able to determine which devices are outstations, and which are masters. Understanding of master devices and their role within control processes can enable the use of Rogue Master Device.|
Inhibit Response Function
|T851||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.59 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||T852||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.60 Analysis of screen captures may provide the adversary with an understanding of intended operations and interactions between critical devices.|
|Scripting||Execution||T853||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.|
|Serial Connection Enumeration||Discovery||T854||Adversaries may perform serial connection enumeration to gather situational awareness after gaining access to devices in the OT network. Control systems devices often communicate to each other via various types of serial communication mediums. These serial communications are used to facilitate informational communication, as well as commands. Serial Connection Enumeration differs from I/O Module Discovery, as I/O modules are auxiliary systems to the main system, and devices that are connected via serial connection are normally discrete systems. While IT and OT networks may work in tandem, the exact structure of the OT network may not be discernible from the IT network alone. After gaining access to a device on the OT network, an adversary may be able to enumerate the serial connections. From this perspective, the adversary can see the specific physical devices to which the compromised device is connected to. This gives the adversary greater situational awareness and can influence the actions that the adversary can take in an attack.|
|Service Stop||Impair Process Control||T881||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.61 Services may not allow for modification of their data stores while running. Adversaries may stop services in order to conduct Data Destruction.61|
|Spearphishing Attachment||Initial Access||T865||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.62|
|Spoof Reporting Message||Evasion|
Impair Process Control
|T856||Adversaries may spoof reporting messages in control systems environments to achieve evasion and assist with impairment of process controls. Reporting messages are used in control systems so that operators and network defenders can understand the status of the network. Reporting messages show the status of devices and any important events that the devices control.
If an adversary has the ability to Spoof Reporting Messages, then they can impact the network in many ways. The adversary can Spoof Reporting Messages that state that the device is in normal working condition, as a form of evasion. The adversary could also Spoof Reporting Messages to make the defenders and operators think that other errors were occurring, to distract them from the actual source of the 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||T869||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||T862||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.F-Secure Labs analyzed the approach the adversary used to compromise victim systems with Havex.63 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
|T857||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.64In the 2015 attack on the Ukranian power grid, the adversaries gained access to the control networks of three different energy companies. The adversaries developed malicious firmware for the serial-to-ethernet devices which rendered them inoperable and severed connections between the control center and the substation.4
|Theft of Operational Information||Impact||T882||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.3433|
|Unauthorized Command Message||Impair Process Control||T855||Adversaries may send unauthorized command messages to instruct control systems devices to perform actions outside their expected functionality for process control. 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 2015 attack on the Ukranian power grid, the adversaries gained access to the control networks of three different energy companies. The adversaries used valid credentials to seize control of operator workstations and access a distribution management system (DMS) client application via a VPN. The adversaries used these tools to issue unauthorized commands to breakers at substations which caused a loss of power to over 225,000 customers over various areas.4
|User Execution||Execution||T863||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.65 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.66|
|Utilize/Change Operating Mode||Evasion|
Inhibit Response Function
|T858||Adversaries may place controllers into an alternate mode of operation to enable configuration setting changes for evasive code execution or to inhibit device functionality. Programmable controllers typically have several modes of operation. These modes can be broken down into three main categories: program run, program edit, and program write. Each of these modes puts the device in a state in which certain functions are available. For instance, the program edit mode allows alterations to be made to the user program while the device is still online. By driving a device into an alternate mode of operation, an adversary has the ability to change configuration settings in such a way to cause a Impact to equipment and/or industrial process associated with the targeted device. An adversary may also use this alternate mode to execute arbitrary code which could be used to evade defenses.|
|T859||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.65
The 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.In the 2015 attack on the Ukranian power grid, the adversaries used valid credentials to interact directly with the client application of the distribution management system (DMS) server via a VPN and native remote access services to access employee workstations hosting HMI applications.4 The adversaries caused outages at three different energy companies, causing loss of power to over 225,000 customers over various areas.4
|Wireless Compromise||Initial Access||T860||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.6768 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.89 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.10 The controller then enabled initial access to the network, allowing the capture and replay of tram signals.8
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