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name: d3fend-isolate description: | Guides cybersecurity isolation controls using MITRE D3FEND—access mediation, content filtering, execution isolation, and network segmentation. Covers access policies, permissions, content validation, process isolation, allowlisting, and traffic filtering. Use when segmenting networks, restricting access, filtering content, or isolating execution—not for detection (d3fend-detect), hardening (d3fend-harden), or deception (d3fend-deceive).

D3FEND — Isolate

When to Use

• Implementing access mediation (network, file, web session, physical)
• Configuring content filtering and validation (format, metadata, magic bytes)
• Isolating execution (process sandboxing, allowlisting, denylisting)
• Segmenting networks (VLANs, micro-segmentation, broadcast isolation)
• Managing DNS/IP allowlists and denylists
• Setting system call filtering and I/O port restrictions

When NOT to Use

• Building detection rules or monitoring → d3fend-detect
• System hardening or encryption → d3fend-harden
• Honeypots or deception → d3fend-deceive
• Network architecture design → infrastructure-engineer
• Zero-trust implementation → cybersecurity

Core Workflows

1. Access Mediation

Type	Controls
Network	VLANs, ACLs, routing mediation, remote file access
Web Session	Proxy-based, endpoint-based mediation
File	Local permissions, access policy administration
Physical	Locks, badges, physical access mediation
System	System call filtering, I/O port restrictions

See references/access_mediation.md

2. Content Filtering & Validation

• Content filtering (email, web, DLP)
• Content modification, excision, rebuild, substitution
• Format verification (magic bytes, metadata, internal structure)
• Decompression checking and quarantine

See references/content_filtering.md

3. Execution Isolation

• Application-based process isolation (containers, app sandbox)
• Kernel-based isolation (seccomp, namespaces, cgroups)
• Hardware-based isolation (TEE, TPM, enclaves)
• Executable allowlisting and denylisting

See references/execution_isolation.md

4. Network Isolation

• Broadcast domain isolation (VLANs, private VLANs)
• Directional network links (one-way gateways)
• DNS/IP allowlisting and denylisting
• Encrypted tunnels (VPN, TLS, IPsec)
• Traffic filtering (inbound, outbound, email)

See references/network_isolation.md

When to load references

• Access mediation → references/access_mediation.md
• Content filtering → references/content_filtering.md
• Execution isolation → references/execution_isolation.md
• Network isolation → references/network_isolation.md