# Performing S7comm Protocol Security Analysis

> Use when perform security analysis of Siemens S7comm and S7CommPlus protocols used by SIMATIC S7 PLCs to identify vulnerabilities including replay attacks, integrity bypass, unauthorized CPU stop commands, and program download manipulation exploiting weaknesses in S7-300, S7-400, S7-1200, and S7-1500 controllers. . Use when working with performing s7comm protocol security analysis.

- Skill: `oyi77/performing-s7comm-protocol-security-analysis` (Agent Skill)
- Install (CLI): `npx skillmds add oyi77/performing-s7comm-protocol-security-analysis`
- Raw SKILL.md: https://api.skillmd.com/api/skills/oyi77/performing-s7comm-protocol-security-analysis/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- License: Apache-2.0
- Author: oyi77 (https://skillmd.com/u/oyi77)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/oyi77/performing-s7comm-protocol-security-analysis

---


# Performing S7Comm Protocol Security Analysis

## Overview

Cybersecurity skill for performing s7comm protocol security analysis. Follows industry best practices and security standards.

## When to Use
**Trigger phrases:**
- "performing s7comm protocol security analysis"
- "Perform security analysis of Siemens S7comm and S7CommPlus protocols used by SIM"


- When assessing the security posture of Siemens SIMATIC S7 PLC environments
- When building detection rules for S7comm-based attacks against S7-300/400/1200/1500 controllers
- When performing a security audit of Siemens Step 7/TIA Portal communications
- When investigating suspected unauthorized access to Siemens PLC programs
- When evaluating S7CommPlus integrity mechanisms and their bypass potential

**Do not use** for scanning production Siemens PLCs without authorization and a test plan (this can crash controllers), for non-Siemens protocol analysis (see detecting-modbus-command-injection-attacks for Modbus), or for modifying PLC programs in a production environment.


## When NOT to Use

- When you lack proper authorization for testing
- For production systems without change management
- When the task requires legal or compliance expertise beyond technical scope


## Prerequisites

- Network access to the S7comm communication segment (TCP port 102)
- Wireshark with S7comm dissector or Zeek with S7comm protocol analyzer
- Authorized access for security testing (never scan production PLCs without authorization)
- Knowledge of the Siemens PLC models and firmware versions in scope
- Understanding of S7comm protocol structure (COTP, S7 PDU, function codes)

## Workflow

```python
# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}
```

1. **Plan Operations** — Define objectives, scope, and success criteria for s7comm protocol security analysis operations.
2. **Prepare Environment** — Set up tools, access, and data sources required for s7comm protocol security analysis.
3. **Execute Core Workflow** — Perform the s7comm protocol security analysis operations following established procedures.
4. **Validate Results** — Verify that results meet quality standards and objectives.
5. **Report Findings** — Document results, observations, and recommendations.
6. **Follow Up** — Track remediation actions and verify fixes where applicable.

## Tools

- **Analysis Platform** — Data processing and visualization
- **Collaboration Tools** — Team coordination and knowledge sharing


## Process

1. **Reconnaissance** — Gather target information, identify attack surface, enumerate services
1. **Analysis/Exploitation** — Execute the technique, analyze results, document findings
1. **Reporting** — Document IOCs, write findings, provide remediation recommendations

## Verification

- [ ] All s7comm protocol security analysis procedures executed completely and documented
- [ ] Findings validated against multiple data sources
- [ ] False positives identified and filtered
- [ ] Results documented with evidence and timestamps
- [ ] Recommendations provided with risk-based prioritization

## Anti-Rationalization Table

| Rationalization | Reality |
|---|---|
| "We are too small to be targeted" | Automated attacks target everyone. Size does not matter. |
| "Security slows us down" | A breach slows you down 100x more. Build security in from the start. |
| "We will fix it after launch" | Vulnerabilities in production are exploited within hours. Fix before deploy. |