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- Add scripts/agent.py and references/api-reference.md to all remaining skills - Update all 648 LICENSE files: copyright now reads 'Mahipal' - Add implementing-security-monitoring-with-datadog (new skill with full anatomy) - All 649 skills now have: SKILL.md, LICENSE, scripts/agent.py, references/api-reference.md
81 lines
2.3 KiB
Markdown
81 lines
2.3 KiB
Markdown
# S7comm Protocol Security Analysis - API Reference
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## pyshark Library
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Python wrapper for TShark (Wireshark CLI) for packet analysis.
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### Loading S7comm Traffic
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```python
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import pyshark
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cap = pyshark.FileCapture("traffic.pcap", display_filter="s7comm")
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for pkt in cap:
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s7_layer = pkt.s7comm
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print(s7_layer.rosctr, s7_layer.param_func)
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cap.close()
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```
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### Key S7comm Layer Fields
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| Field | Description |
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|-------|-------------|
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| `s7comm.rosctr` | PDU type: 1=Job, 2=Ack, 3=Ack-Data, 7=Userdata |
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| `s7comm.param_func` | Function code (hex) |
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| `s7comm.error_class` | Error class (0 = no error) |
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| `s7comm.error_code` | Specific error code |
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| `s7comm.param_data` | Parameter data payload |
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## S7comm Function Codes
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| Code | Name | Risk Level |
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|------|------|------------|
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| 0x04 | Read Var | Low - read process data |
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| 0x05 | Write Var | High - modify PLC memory |
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| 0x28 | Setup Communication | Low - session init |
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| 0x29 | PLC Run | Critical - start PLC execution |
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| 0x1a | PLC Stop | Critical - halt PLC execution |
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| 0xf0 | Userdata | Medium - diagnostics/programming |
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## S7comm Protocol Overview
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S7comm runs over ISO-on-TCP (RFC 1006) on port 102. The protocol stack:
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1. TCP connection on port 102
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2. TPKT header (RFC 1006)
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3. COTP connection-oriented transport (ISO 8073)
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4. S7comm PDU
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### Security Concerns
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- No built-in authentication in S7comm (pre-S7comm-Plus)
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- No encryption of traffic
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- Write operations can modify PLC logic and process values
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- Stop/Run commands can halt industrial processes
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## Detection Patterns
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### Unauthorized Access
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Multiple unique source IPs connecting to a single PLC (> 3 sources) indicates potential unauthorized access.
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### Brute Force
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Repeated error responses (error_class != 0) from a PLC to a single source exceeding threshold count.
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### Dangerous Operations
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Any write_var, run, or stop function codes should be flagged and correlated with authorized change windows.
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## Output Schema
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```json
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{
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"report": "s7comm_protocol_security_analysis",
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"total_s7_packets": 1500,
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"total_findings": 8,
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"severity_summary": {"critical": 2, "high": 5, "medium": 1},
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"traffic_patterns": {"function_distribution": {"read_var": 1200, "write_var": 50}},
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"findings": [{"type": "dangerous_operation_stop", "severity": "critical"}]
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}
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```
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## CLI Usage
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```bash
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python agent.py --pcap capture.pcap --brute-threshold 10 --output report.json
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```
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