Adversaries may attempt to leverage Application Program Interfaces (APIs) used for communication between control software and the hardware. Specific functionality is often coded into APIs which can be called by software to engage specific functions on a device or other software.
| ID | Name | Description |
|---|---|---|
| G1027 | CyberAv3ngers |
During the 2026 Iranian Water Campaign, CyberAv3ngers leveraged existing PLC management protocols through the manufacturer’s engineering tools. These include EtherNet/IP CIP, S7Comm, and UMAS.[1] |
| S1009 | Triton |
Triton leverages a reconstructed TriStation protocol within its framework to trigger APIs related to program download, program allocation, and program changes. [2] |
| ID | Mitigation | Description |
|---|---|---|
| M0801 | Access Management |
Access Management technologies can be used to enforce authorization policies and decisions, especially when existing field devices do not provide capabilities to support user identification and authentication. [3] These technologies typically utilize an in-line network device or gateway system to prevent access to unauthenticated users, while also integrating with an authentication service to first verify user credentials. |
| M0800 | Authorization Enforcement |
All APIs used to perform execution, especially those hosted on embedded controllers (e.g., PLCs), should provide adequate authorization enforcement of user access. Minimize user's access to only required API calls. [4] |
| M0938 | Execution Prevention |
Minimize the exposure of API calls that allow the execution of code. |
| M0804 | Human User Authentication |
All APIs on remote systems or local processes should require the authentication of users before executing any code or system changes. |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0742 | Detection of Execution through API | AN1875 |
Real-time monitoring identifies an unrecognized process on an ICS Linux host loading an ICS/vendor shared library that is normally restricted to approved control or engineering applications. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. |
| AN2208 |
Monitor OPC UA server audit events for state-changing Write or Method service invocations and compare ClientUserId, ClientApplicationUri, SourceNode/MethodId, status, and arguments with the approved client/method baseline. For servers that support auditing, AuditWriteUpdateEventType and AuditUpdateMethodEventType provide an analyst-visible record of writes and state-changing method calls. Alert on successful or attempted control operations from unapproved clients/users or against methods/nodes outside the documented engineering workflow; do not describe this as Windows OS API telemetry. |
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| AN2239 |
Real-time monitoring identifies Open Platform Communications (OPC) Unified Architecture (UA) method invocations or International Electrotechnical Commission (IEC) 61850 Abstract Common Services Interface (ACSI) service requests arriving at a field device from a client identity not in the approved application allowlist, where the invoked method is a write or control operation rather than read/subscribe. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. |
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| AN2289 |
Real-time monitoring identifies network traffic to Industrial Control System (ICS) Application Programming Interface (API) ports such as 4840 used in the Open Platform Communications (OPC) Unified Architecture (UA) or vendor-specific API ports from source Internet Protocol (IP) addresses not in the approved application client list, where the traffic pattern is consistent with write/control method invocations rather than subscription/read traffic. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance. |