The adversary is trying to maintain their foothold in your ICS environment. Persistence consists of techniques that adversaries use to maintain access to ICS systems and devices across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that allow them to secure their ongoing activity and keep their foothold on systems. This may include replacing or hijacking legitimate code, firmware, and other project files, or adding startup code and downloading programs onto devices.

Subissues

Issuelinks
Insecure Credentials Adversaries may target insecure credentials as a means to persist on a system or device or move laterally from one system or device to another. Insecure credentials may appear as default credentials which are pre-configured credentials on a system, device, or software that are well-known in documentation or hard-coded credentials which are built into the system, device, or software that cannot be changed or not easily changed because of the impact on control processes.(Citation: NIST SP 800-82r3)(Citation: ICS-ALERT-13-164-01)(Citation: OT IceFall) Adversaries often times use insecure credentials to evade detection as they are typically forgotten about by system and device owners.
Modify Firmware Firmware is low-level software embedded in hardware that enables systems and devices to function properly and is commonly found in ICS environments. Adversaries may modify firmware on a system or device by installing malicious or vulnerable versions that enable them to achieve objectives such as [Persistence](https://attack.mitre.org/tactics/TA0110), [Impair Process Control](https://attack.mitre.org/tactics/TA0106), and [Inhibit Response Function](https://attack.mitre.org/tactics/TA0107). Adversaries may modify system and device firmware by using the built-in firmware update functionality which may support local or remote installation. The malicious or vulnerable firmware may be delivered via [Replication Through Removable Media](https://attack.mitre.org/techniques/T0847), [Supply Chain Compromise](https://attack.mitre.org/techniques/T0862), or [Remote Services](https://attack.mitre.org/techniques/T0886). Once installed, the malicious or vulnerable firmware could be used to provide [Rootkit](https://attack.mitre.org/techniques/T0851) and [Hooking](https://attack.mitre.org/techniques/T0874) functionality, [Exploitation for Privilege Escalation](https://attack.mitre.org/techniques/T0890), or [Denial of Service](https://attack.mitre.org/techniques/T0814).(Citation: Basnight, Zachry, et al.)
Valid Accounts 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. (Citation: Booz Allen Hamilton) 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.
Project File Infection 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.(Citation: Beckhoff) 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](https://attack.mitre.org/tactics/TA0104) and [Persistence](https://attack.mitre.org/tactics/TA0110) techniques.(Citation: PLCdev) Adversaries may export their own code into project files with conditions to execute at specific intervals.(Citation: Nicolas Falliere, Liam O Murchu, Eric Chien February 2011) 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.(Citation: PLCdev)
Modify Program 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) (Citation: IEC February 2013) 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.

Linked Issues

Issuelinks
is related to Tactics
is part of ICS ATT&CK
Impressum German English