mirror of
https://github.com/mukul975/Anthropic-Cybersecurity-Skills.git
synced 2026-06-12 14:14:56 +03:00
mukul975
27c6414ca5
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
65 lines
1.6 KiB
Markdown
65 lines
1.6 KiB
Markdown
# API Reference: Detecting Modbus Protocol Anomalies
|
|
|
|
## Modbus Protocol Limits
|
|
|
|
| Parameter | Maximum Value |
|
|
|-----------|--------------|
|
|
| Coil read quantity | 2000 |
|
|
| Register read quantity | 125 |
|
|
| Register write quantity | 123 |
|
|
| Unit ID range | 1-247 |
|
|
| PDU size | 253 bytes |
|
|
|
|
## Anomaly Detection Methods
|
|
|
|
| Anomaly | Detection | Severity |
|
|
|---------|-----------|----------|
|
|
| Timing deviation | Polling interval outside tolerance | MEDIUM-HIGH |
|
|
| Excessive read | Quantity > protocol limits | HIGH |
|
|
| Invalid function code | Not in standard set | HIGH |
|
|
| Modbus scan | >5 unique function codes from source | HIGH |
|
|
| Register range violation | Address outside configured range | MEDIUM |
|
|
|
|
## Zeek Modbus Log Fields
|
|
|
|
```
|
|
#fields ts uid id.orig_h id.orig_p id.resp_h id.resp_p func exception quantity
|
|
```
|
|
|
|
## Suricata Modbus Rules
|
|
|
|
```
|
|
alert modbus any any -> any 502 (msg:"Modbus Invalid Function Code"; \
|
|
modbus: function !1,!2,!3,!4,!5,!6,!15,!16; sid:4000001;)
|
|
alert modbus any any -> any 502 (msg:"Modbus Excessive Register Read"; \
|
|
modbus: function 3; modbus: quantity > 125; sid:4000002;)
|
|
```
|
|
|
|
## Scapy Modbus Analysis
|
|
|
|
```python
|
|
from scapy.contrib.modbus import ModbusADURequest
|
|
from scapy.all import rdpcap
|
|
|
|
pkts = rdpcap("modbus.pcap")
|
|
for pkt in pkts:
|
|
if pkt.haslayer(ModbusADURequest):
|
|
print(f"FC={pkt.funcCode} Len={pkt.len}")
|
|
```
|
|
|
|
## Baseline Monitoring
|
|
|
|
```python
|
|
# Expected polling behavior
|
|
expected_interval = 1.0 # seconds
|
|
tolerance = 0.5
|
|
# Alert if interval < 0.5s or > 3.0s
|
|
```
|
|
|
|
## CLI Usage
|
|
|
|
```bash
|
|
python agent.py --modbus-log modbus.log
|
|
python agent.py --modbus-log modbus.log --expected-interval 2.0
|
|
```
|