Point & Tag Identification
|Point & Tag Identification|
|Data Sources||Network protocol analysis, Packet capture, Netflow/Enclave netflow|
|External Contributors||Jos Wetzels - Midnight Blue|
|Asset||Data Historian, Control Server, Human-Machine Interface|
Adversaries may collect point and tag values to gain a more comprehensive understanding of the process environment. Points may be values such as inputs, memory locations, outputs or other process specific variables.1 Tags are the identifiers given to points for operator convenience.
Collecting such tags provides valuable context to environmental points and enables an adversary to map inputs, outputs, and other values to their control processes. Understanding the points being collected may inform an adversary on which processes and values to keep track of over the course of an operation.
- Backdoor.Oldrea enumerates all OPC tags and queries for specific fields such as server state, tag name, type, access, and id.2
- Authorization Enforcement - Systems and devices should restrict access to any data with potential confidentiality concerns, including point and tag information.
- Human User Authentication - All field controllers should require users to authenticate for all remote or local management sessions. The authentication mechanisms should also support Account Use Policies, Password Policies, and User Account Management.
- Communication Authenticity - Protocols used for control functions should provide authenticity through MAC functions or digital signatures. If not, utilize bump-in-the-wire devices or VPNs to enforce communication authenticity between devices that are not capable of supporting this (e.g., legacy controllers, RTUs).
- Network Allowlists - Use host-based allowlists to prevent devices from accepting connections from unauthorized systems. For example, allowlists can be used to ensure devices can only connect with master stations or known management/engineering workstations.3
- Access Management - Authenticate all access to field controllers before authorizing access to, or modification of, a device's state, logic, or programs. Centralized authentication techniques can help manage the large number of field controller accounts needed across the ICS.
- Software Process and Device Authentication - Devices should authenticate all messages between master and outstation assets.
- Network Segmentation - Segment operational assets and their management devices based on their functional role within the process. Enabling more strict isolation to more critical control and operational information within the control environment.4536
- Filter Network Traffic - Perform inline allowlisting of automation protocol commands to prevent devices from sending unauthorized command or reporting messages. Allow/denylist techniques need to be designed with sufficient accuracy to prevent the unintended blocking of valid messages.
- Benjamin Green. (n.d.). On the Significance of Process Comprehension for Conducting Targeted ICS Attacks. Retrieved November 1, 2019.
- Kyle Wilhoit. (2014, July 17). Havex, It’s Down With OPC. Retrieved October 22, 2019.
- Department of Homeland Security. (2016, September). Retrieved September 25, 2020.
- Karen Scarfone; Paul Hoffman. (2009, September). Guidelines on Firewalls and Firewall Policy. Retrieved September 25, 2020.
- Keith Stouffer. (2015, May). Guide to Industrial Control Systems (ICS) Security. Retrieved March 28, 2018.
- Dwight Anderson. (2014). Protect Critical Infrastructure Systems With Whitelisting. Retrieved September 25, 2020.