Operational technology communications occur over serial COM, Ethernet, Wi-Fi, cellular (4G/5G), and satellite mediums. Adversaries may block communications to prevent reporting messages and command messages from reaching their intended target devices disrupting processes, operations, and causing cyber-physical impacts.(Citation: Bonnie Zhu, Anthony Joseph, Shankar Sastry 2011) Adversaries may block communications by either making modifications to software ([System Firmware](https://attack.mitre.org/techniques/T0857), [Module Firmware](https://attack.mitre.org/techniques/T0839), [Hooking](https://attack.mitre.org/techniques/T0874), and [Rootkit](https://attack.mitre.org/techniques/T0851)) and services ([Service Stop](https://attack.mitre.org/techniques/T0881), [Denial of Service](https://attack.mitre.org/techniques/T0814)) on systems and devices or by positioning themselves between systems and devices and intercepting and blocking the communications such as the case with an [Adversary-in-the-Middle](https://attack.mitre.org/techniques/T0830) attack.

Subissues

Issuelinks
Bezeichnung Beschreibung
Serial COM 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 10.0.0.1 via Telnet on serial port 1 with the following command: telnet 10.0.0.1 20001.
Ethernet Adversaries may block access to Ethernet communications to prevent instructions or configurations messages from reaching target systems and devices. Ethernet connections allow for communications between IT and OT systems and devices. Blocking Ethernet communications may also block command and reporting messages.(Citation: Bonnie Zhu, Anthony Joseph, Shankar Sastry 2011) An adversary may block Ethernet communications by disabling network interfaces, [Service Stop](https://attack.mitre.org/techniques/T0881), or conducting an [Adversary-in-the-Middle](https://attack.mitre.org/techniques/T0830) attack and dropping the network traffic.
Wi-Fi Adversaries may block access to Wi-Fi communications to prevent messages from reaching target systems and devices. Wi-Fi connections allow for communications between IT and OT systems and devices. Blocking Wi-Fi communications may also block command and reporting messages.(Citation: Bonnie Zhu, Anthony Joseph, Shankar Sastry 2011) An adversary may block Wi-Fi communications by disabling network interfaces, [Service Stop](https://attack.mitre.org/techniques/T0881), conducting an [Adversary-in-the-Middle](https://attack.mitre.org/techniques/T0830) attack and dropping the network traffic, or by jamming the Wi-Fi signal.

Linked Issues

Issuelinks
Linktyp Issue
is related to Techniques
is related to Programmable Logic Controller (PLC)
is related to Jump Host
is related to Distributed Control System (DCS) Controller
is related to Control Server
is related to Workstation
is related to Switch
is related to Application Server
is related to Remote Terminal Unit (RTU)
is related to Programmable Automation Controller (PAC)
is related to Virtual Private Network (VPN) Server
is related to Data Historian
is related to Intelligent Electronic Device (IED)
is related to Safety Controller
is related to Data Gateway
is related to Firewall
is related to Field I/O
is related to Routers
is related to Human-Machine Interface (HMI)
is blocked by Detection of Block Communications
is blocked by Out-of-Band Communications Channel
is blocked by Network Segmentation
is blocked by Network Allowlists
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