plc-code-analysis

name plc-code-analysis description Standalone skill for multi-perspective PLC code security and quality analysis. Triggers on: "review", "audit", "analyze", "security check", "vulnerability scan", "code review", "check this code", "is this safe", "find issues" when combined with PLC, SCL, ST, LAD, FBD, Structured Text, or block context. Also triggers when the user pastes PLC code and asks for feedback, or uploads exported SimaticML XML files. This skill is independent of tia-openness-roadmap — it does not perform engineering automation. It analyzes code that has already been exported, pasted, or is accessible via the TIA Portal MCP server. license MIT disable-model-invocation true plc-code-analysis Goal Perform structured, multi-perspective security and quality analysis of PLC code, producing a severity-ranked findings report. Acts as an automated "second pair of eyes" for automation engineers. Independence from tia-openness-roadmap This skill is NOT routed by tia-openness-roadmap . It has its own trigger patterns and operates independently. The Openness roadmap handles engineering automation (create, modify, import/export via API). This skill handles analysis and review of existing code. The skill can consume code retrieved through an integration or exported through Openness/VCI, but it does not depend on a particular wrapper. Input recognition PLC code commonly arrives in one of four ways. Identify the exact format and provenance before analysis. Format 1 — Raw SCL / Structured Text The user pastes or uploads .scl , .st , or plain-text PLC code. This is the simplest case. Parse directly as text. Look for FUNCTION_BLOCK, FUNCTION, ORGANIZATION_BLOCK, DATA_BLOCK headers to identify block boundaries. Format 2 — SIMATIC SD source documents (V21) TIA Portal V21 can export S7-1200/S7-1500 SCL, LAD, FBD, DB, F-DB, UDT, and F-UDT content in the text-based SIMATIC Source Document format. Analyze the .s7dcl declaration/code document together with its .s7res resources when both exist. Preserve document paths and identifiers so findings can be traced back. SIMATIC SD is a source representation, not runtime evidence. In particular, an SCL block can be exported even when it is not compile-clean; successful export does not prove a successful compile, download, or PLC behavior. Format 3 — SimaticML XML (exported LAD/FBD/SCL) The user provides .xml files exported from TIA Portal. These follow the SimaticML schema. Key navigation points: <SW.Blocks.FB> , <SW.Blocks.FC> , <SW.Blocks.OB> , <SW.Blocks.DB> — block type <Interface> → <Section Name="Input|Output|InOut|Static|Temp|Constant"> — variable declarations <ObjectList> → <CompileUnit> — individual networks <FlgNet> inside CompileUnit — LAD/FBD network logic as a directed graph <Access> elements — variable references with scope and UID <Part> elements — instructions (contacts, coils, function calls) <Wire> elements — connections between parts (data/signal flow) <StructuredText> — SCL compile-unit content, including inline SCL in LAD/FBD <Comment> — block and network comments (valuable for process context) Root block kind ( SW.Blocks.FB , SW.Blocks.FC , SW.Blocks.OB , or SW.Blocks.GlobalDB ) and <AttributeList> elements such as <Number> , <ProgrammingLanguage> , and <MemoryLayout> (Optimized/Standard) Validate XML against the installed V21 schemas rather than assuming a historical schema revision. The installed SCL schema is SW.PlcBlocks.SCL_v4.xsd ; LAD/FBD and shared interface schemas are separate. For LAD/FBD analysis, reconstruct the logic flow from the <FlgNet> graph: Parts are nodes, Wires are edges. Follow Powerrail → Contact chain → Coil/Function to understand each network's behavior. Format 4 — MCP-assisted retrieval If the TIA Portal MCP server is available, context retrieval is required before issuing security findings. Use the current Totally Integrated Claude MCP tools: browse_project_tree — map PLCs, block folders, block names, and execution entry points get_block_content — retrieve SIMATIC SD YAML for each block under review list_tag_tables — retrieve PLC tags, user constants, and externally writable names read_cross_references — inspect call paths, unused blocks, and variable references read_hardware_config — retrieve CPU, network, IP, subnet, and interface settings compile_check — record compile errors/warnings when the user asks for remediation Legacy source documents may name equivalent operations as GetBlocksWithHierarchy , ExportBlock , GetBlockInfo , GetTypes / GetTypeInfo , or GetHardwareConfig . Treat those as conceptual aliases, not callable tool names. If MCP is unavailable or a required context item cannot be retrieved, continue only as a limited review. The final report must include a context manifest and mark affected findings as inference-based where missing declarations, UDTs, call paths, tag tables, or hardware mapping prevent confirmation. Analysis workflow The analysis is performed in sequential passes. Each pass loads one reference file, analyzes the code through that specific lens, and produces findings. Critical instruction: After each pass, Claude summarizes the findings from that pass in a compact internal list before loading the next reference. This prevents token pressure from accumulating raw analysis across all passes. Pass order Pass Reference file Focus 1 references/process-architect.md Physical plausibility and process context 2 references/security-practices.md Top 20 Secure PLC Coding Practices + communication hardening 3 references/threat-mapping.md MITRE ATT&CK for ICS technique identification 4 references/compiler-critic.md Siemens platform bugs, CWE memory safety, safety boundary 5 references/hardware-reviewer.md Hardware config, access settings, network security Pass order rationale: Process context comes first because understanding what the code physically controls determines the severity of all subsequent findings. A missing range check on a status indicator is Low; the same flaw on a chemical dosing pump is Critical. Per-pass procedure Before starting the passes, build a compact context manifest: Code: pasted/exported blocks, block names, language, line/network references Declarations: VAR_INPUT, VAR_OUTPUT, VAR_IN_OUT, VAR_STATIC, VAR_TEMP, constants Types: UDTs, arrays, structures, optimized vs standard access metadata when known Flows: call tree, cross references, external write sources, HMI/SCADA inputs Hardware: CPU, communication settings, network interfaces, safety-related mapping Verification: baseline compile status if available, and whether simulation was run For each pass: Load the reference file Work through every checklist item against the provided code Record each finding with: severity, category tag, location, evidence, inference level, description, impact, remediation, and verification requirement Produce a compact summary of findings from this pass Proceed to next pass After all passes, run a final verification synthesis: Challenge high/critical findings against the context manifest Downgrade or label findings that depend on missing UDTs, call paths, or hardware mapping Flag any proposed remediation that requires compile_check , simulation, or safety review Do not present generated PLC code as deployable without compile and engineering validation Every finding must be source-backed: cite the supplied line/network/XML/SD node or retrieved artifact that supports it. A checklist match without the required context is a review question or verification request, not a confirmed vulnerability. Hardware reviewer conditionality If no hardware configuration data is available (user only provided code, no HW config, no MCP access), the Hardware Reviewer pass still runs but produces a single finding: #### [INFO] Hardware configuration not available - **Category:** HW-REVIEW - **Description:** No hardware configuration data was provided or retrievable. The following checks could not be performed: PUT/GET access status, web server settings, communication protocol security, access level configuration, protection level status. - **Evidence:** No `read_hardware_config` result or hardware export was available. - **Inference level:** Confirmed limitation - **Verification required:** Provide hardware export or enable MCP hardware retrieval. - **Remediation:** Provide hardware configuration export or enable MCP server access for a complete security assessment. Output format After all passes complete, merge findings, deduplicate (same issue found by multiple passes gets the highest severity assigned and cross-references both categories), and sort by severity. ## PLC Code Analysis Report **Analyzed:** [block names / file names] **Input format:** SCL/ST / SIMATIC SD / SimaticML XML (SCL/LAD/FBD) **Analysis date:** [date] **Passes completed:** Process Architect, Security Practices, Threat Mapping, Compiler Critic, Hardware Reviewer, Verification Synthesis ### Context Manifest | Context item | Status | Source | |--------------|--------|--------| | Block logic | Provided / Retrieved / Missing | Paste / file / `get_block_content` | | Variable declarations | Complete / Partial / Missing | block interface / XML / YAML | | UDT and array definitions | Complete / Partial / Missing | source / `get_block_content` | | Call tree and cross references | Complete / Partial / Missing | `browse_project_tree` / `read_cross_references` | | Tag tables and external inputs | Complete / Partial / Missing | `list_tag_tables` | | Hardware and network config | Complete / Partial / Missing | `read_hardware_config` / export | | Compile baseline | Clean / Warnings / Errors / Not run | `compile_check` / not available | ### Summary | Severity | Count | |----------|-------| | CRITICAL | N | | HIGH | N | | MEDIUM | N | | LOW | N | | INFO | N | ### Findings #### [CRITICAL] Finding title - **Category:** TOP20-P08 / CWE-787 / T0836 / HW-PUTGET (one or more) - **Location:** FB _MixerControl, Line 47 / Network 3 - **Evidence:** Direct source evidence or retrieved MCP context supporting the finding - **Inference level:** Confirmed / Probable / Suspicious / Context-limited - **Confidence:** High / Medium / Low - **Description:** Clear explanation of the issue - **Impact:** What could happen if this is exploited or left unaddressed - **Remediation:** Specific, actionable fix with code example where applicable - **Verification required:** compile_ check / simulation / safety review / hardware review - **References:** Relevant standard or practice citation --- [... next finding ...] Severity definitions Severity Criteria CRITICAL Direct risk to physical safety, process integrity, or enables remote code execution. Immediate action required. HIGH Significant security gap exploitable by network-level attacker, or logic flaw affecting process control under fault conditions. MEDIUM Violation of secure coding practice that increases attack surface or reduces defense-in-depth, but requires additional conditions to exploit. LOW Code quality or style issue that indirectly weakens security posture. Best-practice deviation without immediate risk. INFO Observation, recommendation, or note about missing context that prevented a complete check. Limitations and honest reporting Claude must NOT: Invent findings to fill the report — if a pass finds nothing, report "No issues identified" Speculate about code behavior without evidence from the provided source Claim certainty about runtime behavior that depends on CPU configuration not provided Hallucinate variable names, block numbers, or line references Claude MUST: Clearly state when a finding is based on inference vs. direct evidence Note when analysis is limited by missing context (e.g., UDT definitions not provided) Distinguish between confirmed violations and suspicious patterns worth investigating