# Containing Active Breach

> Use when executes containment strategies to stop active adversary operations and prevent lateral movement during a confirmed security breach. Implements short-term and long-term containment using network segmentation, endpoint isolation, credential revocation, and access control modifications. Activates for requests involving breach containment, lateral movement prevention, network isolation, active threat containment, or live incident response. '.

- Skill: `oyi77/containing-active-breach` (Agent Skill)
- Install (CLI): `npx skillmds add oyi77/containing-active-breach`
- Raw SKILL.md: https://api.skillmd.com/api/skills/oyi77/containing-active-breach/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/containing-active-breach

---


# Containing Active Breach

## Overview

Cybersecurity skill for containing active breach. Follows industry best practices and security standards.

## When to Use
**Trigger phrases:**
- "containing active breach"
- "Executes containment strategies to stop active adversary operations and prevent "


- A confirmed intrusion is in progress with an active adversary on the network
- Malware is spreading laterally across endpoints or servers
- A compromised account is being used for unauthorized access to systems
- Ransomware encryption has been detected and is actively propagating
- An attacker has established command-and-control communications from internal hosts

**Do not use** for post-incident cleanup when the adversary is no longer active; use eradication procedures instead.


## 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

- Confirmed incident classification with P1 or P2 severity from triage
- EDR console access with host isolation capabilities (CrowdStrike Falcon, Microsoft Defender for Endpoint, SentinelOne)
- Network firewall and switch management access for segmentation
- Active Directory or identity provider administrative access for credential actions
- Pre-approved containment authority documented in the incident response plan
- Evidence preservation plan to avoid destroying forensic artifacts during containment

## 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. **Define Objectives** — Clarify the goals and scope for active breach.
2. **Gather Resources** — Collect tools, data, and access needed for active breach.
3. **Execute Process** — Carry out active breach operations methodically.
4. **Verify Quality** — Check results against acceptance criteria.
5. **Document Outcomes** — Record findings, decisions, and next steps.

## 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 active breach 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. |