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mukul975
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Complete skill folder anatomy across all cybersecurity skills: - scripts/agent.py: 80-150 line Python agents using real libraries (impacket, boto3, azure-mgmt-*, kubernetes, pefile, yara, scapy, shodan, stix2, etc.) - references/api-reference.md: real API documentation with method signatures - LICENSE: MIT license for all skill folders
68 lines
1.6 KiB
Markdown
68 lines
1.6 KiB
Markdown
# API Reference: Detecting Modbus Command Injection Attacks
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## Modbus Function Codes
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| Code | Function | Risk |
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|------|----------|------|
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| 1 | Read Coils | Read |
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| 3 | Read Holding Registers | Read |
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| 5 | Write Single Coil | Write (dangerous) |
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| 6 | Write Single Register | Write (dangerous) |
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| 15 | Write Multiple Coils | Write (dangerous) |
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| 16 | Write Multiple Registers | Write (dangerous) |
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| 8 | Diagnostics | Diagnostic |
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## Zeek Modbus Log
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```
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#fields ts uid id.orig_h id.orig_p id.resp_h id.resp_p func
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```
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## Suricata Modbus Rules
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```
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alert modbus any any -> any 502 (msg:"Modbus Write Coil"; \
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modbus: function 5; sid:3000001;)
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alert modbus any any -> any 502 (msg:"Modbus Write Multiple Registers"; \
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modbus: function 16; sid:3000002;)
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```
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## pymodbus Library
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```python
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from pymodbus.client import ModbusTcpClient
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client = ModbusTcpClient("192.168.1.100", port=502)
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client.connect()
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result = client.read_holding_registers(0, 10, slave=1)
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print(result.registers)
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client.close()
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```
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## Scapy Modbus Parsing
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```python
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from scapy.contrib.modbus import ModbusADURequest
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from scapy.all import rdpcap
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pkts = rdpcap("modbus.pcap")
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for pkt in pkts:
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if pkt.haslayer(ModbusADURequest):
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print(f"Function: {pkt.funcCode}")
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```
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## Detection Thresholds
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| Anomaly | Threshold | Severity |
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|---------|-----------|----------|
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| Write flood | >20 writes/60s | CRITICAL |
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| Unknown function code | Any | HIGH |
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| Unauthorized master | Not in allowlist | CRITICAL |
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## CLI Usage
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```bash
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python agent.py --zeek-log modbus.log
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python agent.py --zeek-log modbus.log --authorized-masters 10.0.0.1 10.0.0.2
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```
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