Wed, 04/15/2026 - 9:17pm by admin

Fair correction. Let’s strip it clean and keep only what matters.

🛡️ Isolation & Security Control Sheet

(Reusable — Container-Based Deployment)

1. Core Claim

Isolation is enforced through layered controls across runtime, host, network, and service boundaries. No single mechanism is relied upon as the security boundary.

2. Control Matrix

Claim Control Evidence (what you can show) Residual Risk
Service does not run with elevated privileges Rootless execution using ps output, container config Kernel-level escape vulnerabilities
Filesystem access is restricted Explicit mounts, read-only root filesystem Container run args, mount table Misconfigured writable mounts
Host system is protected SELinux enforcing mode getenforce, file labels Policy misconfiguration
Service cannot access arbitrary user data No broad host directory mounts Mount list, service config Accidental mount expansion
Network exposure is limited Explicit port binding only ss -tulnp, firewall rules Misconfigured firewall
Outbound access is controlled Restricted or no default egress Routing / firewall config Hidden outbound dependencies
Secrets are protected Externalized configuration / runtime injection Config inspection Runtime memory exposure
Admin access is separated Distinct admin endpoints Route map, logs Improper authentication
Actions are auditable Structured logging Log samples Log tampering if host compromised
Service cannot modify host Read-only system paths systemd config Misconfiguration
Runtime behavior is constrained systemd sandboxing (ProtectSystem, etc.) Unit file Compatibility gaps

3. Negative Capability (What the System Cannot Do)

The service is deliberately incapable of:

  • reading arbitrary host directories (e.g., /home, /etc)
  • modifying system binaries or OS configuration
  • opening unsolicited network ports
  • making unrestricted outbound connections
  • accessing unrelated storage or datasets
  • escalating privileges to host root

4. Boundary Definition

Boundary Enforced By Purpose
Process isolation Container runtime Limit process scope
Host protection SELinux Prevent host compromise
Service sandbox systemd Restrict runtime capabilities
Network boundary Firewall / routing Limit communication paths
Identity boundary Auth / tokens Control access

5. When This Design Is Appropriate

  • controlled, known workloads
  • explicit access paths
  • segmented or air-gapped environments
  • clearly defined service roles

6. When to Escalate to a VM Boundary

  • untrusted or user-supplied code execution
  • strict tenant separation requirements
  • compliance-driven isolation
  • need for independent kernel boundary

7. Residual Risk Statement

No system is entirely free of risk. This design minimizes exposure through layered isolation and explicit boundaries. Residual risks primarily relate to host-level vulnerabilities, misconfiguration, or credential compromise.

8. Operational Verification Checklist 

# identity check
id

# process ownership
ps aux | grep <service>

# SELinux status
getenforce

# network exposure
ss -tulnp

# mounted paths
mount | grep <service>

# service sandboxing
systemctl cat <service>

🧠 Final Positioning Line

Isolation is achieved through layered controls. Compromise of one component is designed to be contained rather than propagated.