Program Download

What the technique is

Adversaries may perform a program download to transfer a user program to a controller. Variations of program download, such as online edit and program append, allow a controller to continue running during the transfer and reconfiguration process without interruption to process control. However, before starting a full program download (i.e., download all) a controller may need to go into a stop state. This can have negative consequences on the physical process, especially if the controller is not able to fulfill a time-sensitive action. Adversaries may choose to avoid a download all in favor of an online edit or program append to avoid disrupting the physical process. An adversary may need to use the technique Detect Operating Mode or Change Operating Mode to make sure the controller is in the proper mode to accept a program download. The granularity of control to transfer a user program in whole or parts is dictated by the management protocol (e.g., S7CommPlus, TriStation) and underlying controller API. Thus, program download is a high-level term for the suite of vendor-specific API calls used to configure a controllers user program memory space. Modify Controller Tasking and Modify Program represent the configuration changes that are transferred to a controller via a program download.

What MITRE says you would watch

• AN1884

  Monitor device alarms for program downloads, although not all devices produce such alarms. Monitor for protocol functions related to program download or modification. Program downloads may be observable in ICS automation protocols and remote management protocols. Consult asset management systems to understand expected program versions. Monitor devices configuration logs which may contain alerts that indicate whether a program download has occurred. Devices may maintain application logs that indicate whether a full program download, online edit, or program append function has occurred.