Bastioni Platform: Multi-Tenant Hardening Case Study

Overview

Bastioni is a hybrid wargames platform built for scenario-based cybersecurity training. The primary technical challenge was engineering a secure, multi-tenant Linux environment where players (tenants) could exploit vulnerabilities against adjacent targets without compromising the entire system or affecting other players.

1. Isolation Architecture (Defense in Depth)

The platform implements three core layers of isolation to maintain stability and prevent cross-user pivoting:

A. Split-SSH Access Control

Access is segregated at the network port level:

• Port 22: Restricted to administrators only (key-based authentication).
• Port 2222: Dedicated to players only (password-based authentication via the game_users group).
• Defense: This ensures administrative traffic is isolated from potential player brute-force attempts or protocol abuses, and allows separate Fail2Ban rules for each service.

B. Process and File Hiding

The environment is hardened using system-level controls:

• hidepid=2: Ensures that players cannot see processes belonging to other users or challenge levels, preventing simple scanning for running exploits or user IDs.
• chmod 700: Enforced across all user home directories, ensuring strict privacy for player files and challenge assets.

C. Containerized Boot-to-Root Scenarios

For high-risk challenges (e.g., the Bravo category), a Docker-based architecture is used.

• The vulnerable target is run in an ephemeral container, isolated from the host OS.
• Self-Healing: A nightly reset script automatically tears down and redeploys the container, guaranteeing a fresh, known-good environment for every session.

3. “Charlie” (Forensics & Reversing)

• Concept: Self-contained analysis tasks.
• Tooling: Custom access groups (e.g., tools-gef) grant access to debuggers like GDB/GEF or Radare2 only to specific users, keeping the environment clean.

Operational Utility

While currently an internal research asset, this architecture addresses a critical gap in technical hiring: The lack of operational validation.

Most interview processes rely on theoretical questions. This platform allows for “Live-Fire” assessment:

1. Candidate Access: Generates an ephemeral environment (Concept).
2. Task: “Fix the broken Nginx config” (Blue Team) or “Escalate to Root” (Red Team).
3. Result: A binary Pass/Fail based on flag submission, proving actual keyboard competence.

This system is currently deployed as a private Proxmox lab for infrastructure hardening research.