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. ^[1]

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 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. ^{[2] [3] [4]}

References:

1. ICS-CERT 2017, April 18 CS Alert (ICS-ALERT-17-102-01A) BrickerBot Permanent Denial-of-Service Attack Retrieved. 2019/10/24
2. ICS-CERT 2018, August 27 Advisory (ICSA-15-202-01) - Siemens SIPROTEC Denial-of-Service Vulnerability Retrieved. 2019/03/14
3. Common Weakness Enumeration 2019, January 03 CWE-400: Uncontrolled Resource Consumption Retrieved. 2019/03/14
4. MITRE 2018, March 22 CVE-2015-5374 Retrieved. 2019/03/14