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. [1]

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 T1109 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.

ID: T0851
Sub-techniques:  No sub-techniques
Platforms: Field Controller/RTU/PLC/IED
Version: 1.0
Created: 21 May 2020
Last Modified: 24 May 2022

Procedure Examples

ID Name Description
S0603 Stuxnet

One of Stuxnet's rootkits is contained entirely in the fake s7otbxdx.dll. In order to continue existing undetected on the PLC it needs to account for at least the following situations: read requests for its own malicious code blocks, read requests for infected blocks (OB1, OB35, DP_RECV), and write requests that could overwrite Stuxnets own code. Stuxnet contains code to monitor and intercept these types of requests. The rootkit modifies these requests so that Stuxnets PLC code is not discovered or damaged. [2]


ID Mitigation Description
M0947 Audit

Audit the integrity of PLC system and application code functionality, such as the manipulation of standard function blocks (e.g., Organizational Blocks) that manage the execution of application logic programs. [3]

M0945 Code Signing

Digital signatures may be used to ensure application DLLs are authentic prior to execution.


ID Data Source Data Component
DS0016 Drive Drive Modification
DS0001 Firmware Firmware Modification
DS0011 Module Module Load