# KNEL-Football Security Model ## Overview The KNEL-Football security model implements a defense-in-depth approach to create a highly secure, compliant Debian 13 operating system for tier0 infrastructure access. **Copyright © 2026 Known Element Enterprises LLC** **License: GNU Affero General Public License v3.0 only** ## Security Architecture ### Core Principles 1. **Least Privilege** - Users and processes have only necessary permissions 2. **Defense in Depth** - Multiple layers of security controls 3. **Zero Trust** - No implicit trust, all access must be authorized 4. **Immutability** - System configuration is not easily modifiable 5. **Minimal Attack Surface** - Only necessary services and packages included ### System Hardening Layers #### 1. Boot Security Layer - **UEFI-Only Boot** - No legacy BIOS support prevents boot attacks - **Secure Boot** - Cryptographic verification of bootloader and kernel - **Unified Kernel Image (UKI)** - Signed kernel+initramfs+cmdline bundle - **Kernel Lockdown** - Kernel runs in confidentiality lockdown mode - **Measured Boot** - Boot chain integrity measurement and attestation ##### Secure Boot Trust Chain ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ SECURE BOOT TRUST CHAIN │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────────┐ │ │ │ UEFI Firmware │ ← Root of Trust (Hardware) │ │ └──────────┬──────────┘ │ │ │ Verifies PK signature │ │ ▼ │ │ ┌─────────────────────┐ │ │ │ PK (Platform Key) │ ← RSA-4096, SHA-256, 3650 days │ │ │ Self-signed │ Platform owner authorization │ │ └──────────┬──────────┘ │ │ │ Signs KEK updates │ │ ▼ │ │ ┌─────────────────────┐ │ │ │ KEK (Key Exchange) │ ← RSA-4096, SHA-256, 3650 days │ │ │ Signed by PK │ OS/key exchange authorization │ │ └──────────┬──────────┘ │ │ │ Signs db updates │ │ ▼ │ │ ┌─────────────────────┐ │ │ │ db (Signature DB) │ ← RSA-4096, SHA-256, 3650 days │ │ │ Signed by KEK │ Allowed EFI binaries │ │ └──────────┬──────────┘ │ │ │ Verifies UKI signature │ │ ▼ │ │ ┌─────────────────────┐ │ │ │ UKI (Unified │ ← Signed EFI binary │ │ │ Kernel Image) │ • linuxx64.efi.stub │ │ │ │ • os-release │ │ │ │ • cmdline (lockdown=confidentiality) │ │ │ │ • linux (vmlinuz) │ │ │ │ • initrd (initramfs) │ │ └──────────┬──────────┘ │ │ │ Boots with lockdown │ │ ▼ │ │ ┌─────────────────────┐ │ │ │ Linux Kernel │ ← Kernel Lockdown Mode │ │ │ (Confidentiality) │ • module.sig_enforce=1 │ │ │ │ • No unsigned modules │ │ │ │ • No /dev/mem access │ │ │ │ • No kexec │ │ └─────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` ##### Secure Boot Keys | Key | Purpose | Algorithm | Validity | |-----|---------|-----------|----------| | PK (Platform Key) | Authorizes KEK updates | RSA-4096, SHA-256 | 3650 days | | KEK (Key Exchange Key) | Authorizes db updates | RSA-4096, SHA-256 | 3650 days | | db (Signature Database) | Signs EFI binaries | RSA-4096, SHA-256 | 3650 days | ##### UKI Components | Section | Content | Purpose | |---------|---------|---------| | .osrel | /etc/os-release | OS identification | | .cmdline | Kernel parameters | lockdown=confidentiality, module.sig_enforce=1 | | .linux | vmlinuz-{version} | Kernel image | | .initrd | initrd.img-{version} | Initial ramdisk | ##### Kernel Lockdown Effects When Secure Boot is active and kernel lockdown is enabled: - **No unsigned kernel modules** - module.sig_enforce=1 - **No /dev/mem or /dev/kmem access** - Prevents direct memory manipulation - **No kexec** - Cannot replace running kernel - **No hibernation to untrusted storage** - Prevents data extraction - **No iopl/ioperm** - Restricts I/O port access - **No MSRs from userspace** - Restricts model-specific register access ##### Secure Boot Enforcement - **Build Time**: Keys generated, UKI signed during ISO build - **Install Time**: Keys enrolled in UEFI firmware (setup mode) - **Boot Time**: UEFI verifies UKI signature before boot - **Runtime**: Kernel enforces lockdown mode restrictions #### 2. Network Security Layer - **Network Isolation** - No general internet access - **VPN-Only Access** - WireGuard tunnel required for all network traffic - **Firewall Hardening** - Default deny policy with specific rules - **Wireless Disabled** - WiFi and Bluetooth permanently disabled - **Dynamic Configuration** - Firewall rules adapt to WireGuard endpoints #### 3. System Security Layer - **Kernel Module Blacklisting** - Prevents loading of dangerous modules - **Service Hardening** - Unnecessary services disabled - **Process Isolation** - Application sandboxing where applicable - **Resource Limits** - Prevent resource exhaustion attacks - **Audit Logging** - Comprehensive system activity monitoring #### 4. Access Control Layer - **Strong Authentication** - 14-character minimum password policy - **No Auto-Login** - Manual authentication required - **Privacy Mode** - Usernames hidden in display manager - **Sudo Configuration** - Controlled administrative access - **File Permissions** - Secure access controls on sensitive files #### 5. Application Security Layer - **Minimal Desktop** - IceWM provides minimal attack surface - **Required Applications Only** - Only essential tools included - **Secure Defaults** - Applications configured with secure settings - **No Package Management** - System immutability through disabled package tools ## Threat Model ### Adversary Capabilities | Capability | Mitigation | Effectiveness | |-------------|-------------|---------------| | Network-based attacks | Network isolation, firewall | High | | Local privilege escalation | User permissions, audit | Medium | | Physical access attacks | Encryption, secure boot | High | | Social engineering | Training, documentation | Medium | | Supply chain attacks | Source verification, testing | Medium | ### Attack Scenarios #### Scenario 1: Network-based Attack **Attack:** Attempt to compromise system via network connection **Mitigation:** - No general network access available - Only WireGuard tunnel traffic allowed - Firewall default deny policy - Dynamic endpoint-based rules #### Scenario 2: USB-based Attack **Attack:** Malicious USB device inserted **Mitigation:** - USB devices mounted with restrictive permissions - No auto-execution from removable media - Filesystem permissions restrict access - Audit logging tracks USB activity #### Scenario 3: Local Privilege Escalation **Attack:** User attempts to gain root privileges **Mitigation:** - Strong password policies - Sudo configuration with restrictions - Audit logging tracks privilege usage - System resource limits #### Scenario 4: System Modification **Attack:** Attempt to modify system configuration **Mitigation:** - Package management disabled - Critical system files have immutable attributes - Audit logging tracks configuration changes - Regular compliance checks ## Security Controls ### Preventive Controls 1. **Network Controls** - Module blacklisting for WiFi/Bluetooth - Default deny firewall configuration - VPN-only network access - USB device restrictions 2. **System Controls** - Service hardening and disabling - Strong authentication policies - File permission hardening - System resource limits 3. **Boot Controls** - UEFI-only boot mode - Secure Boot verification - Measured boot attestation ### Detective Controls 1. **Logging and Monitoring** - Comprehensive audit daemon configuration - System event logging - Network traffic logging - User activity tracking 2. **Compliance Validation** - Automated compliance checks - Security configuration verification - Regular security assessments - Vulnerability scanning ### Corrective Controls 1. **Incident Response** - Automated alerting on security events - Isolation capabilities - System recovery procedures - Forensic preservation ## Risk Assessment ### High-Risk Areas 1. **USB Device Handling** - Medium Risk - **Mitigation:** Restrictive mounting, no auto-execution - **Residual Risk:** Low 2. **Physical Access** - Medium Risk - **Mitigation:** Full disk encryption, secure boot - **Residual Risk:** Low 3. **VPN Configuration** - Medium Risk - **Mitigation:** Encrypted configuration, authentication - **Residual Risk:** Low ### Low-Risk Areas 1. **Network-based Attacks** - Low Risk - **Mitigation:** Complete network isolation - **Residual Risk:** Minimal 2. **Remote Exploitation** - Low Risk - **Mitigation:** Minimal services, firewall - **Residual Risk:** Minimal ## Security Validation ### Testing Methodology 1. **Unit Testing** - Individual security function validation 2. **Integration Testing** - End-to-end security workflow testing 3. **Penetration Testing** - External security assessment 4. **Compliance Testing** - Automated validation against standards ### Validation Metrics 1. **Coverage Metrics** - 100% of security controls tested 2. **Compliance Metrics** - 100% compliance with frameworks 3. **Vulnerability Metrics** - Zero critical vulnerabilities 4. **Configuration Metrics** - 100% secure configuration validation ## Continuous Security ### Maintenance 1. **Security Updates** - Through controlled ISO rebuilds 2. **Configuration Changes** - Through verified, version-controlled updates 3. **Compliance Monitoring** - Continuous compliance validation 4. **Security Monitoring** - Real-time security event analysis ### Improvement 1. **Threat Intelligence** - Regular threat model updates 2. **Security Assessments** - Periodic security reviews 3. **Testing Enhancement** - Continuous test suite improvement 4. **Documentation Updates** - Regular security documentation revision --- **Copyright © 2026 Known Element Enterprises LLC** **License: GNU Affero General Public License v3.0 only** This security model is maintained as part of the KNEL-Football project and is updated when security requirements change or new threats emerge.