# APT-OSTree Security Hardening

## Overview

APT-OSTree implements comprehensive security hardening to protect against common attack vectors and ensure secure operation in production environments. The security system provides multiple layers of protection including input validation, privilege escalation protection, secure communication, and security scanning.

## Security Architecture

### Security Layers

```
┌─────────────────────────────────────────┐
│           Security Manager              │
├─────────────────────────────────────────┤
│  ┌─────────────┐  ┌─────────────┐      │
│  │   Input     │  │  Privilege  │      │
│  │ Validation  │  │ Protection  │      │
│  └─────────────┘  └─────────────┘      │
├─────────────────────────────────────────┤
│  ┌─────────────┐  ┌─────────────┐      │
│  │   Secure    │  │   Security  │      │
│  │Communication│  │  Scanning   │      │
│  └─────────────┘  └─────────────┘      │
├─────────────────────────────────────────┤
│  ┌─────────────┐  ┌─────────────┐      │
│  │   Bubblewrap│  │   D-Bus     │      │
│  │  Sandboxing │  │   Security  │      │
│  └─────────────┘  └─────────────┘      │
└─────────────────────────────────────────┘
```

## Security Features

### 1. Input Validation

#### Path Traversal Protection
- Detects and blocks path traversal attempts (`../`, `..\`, etc.)
- Validates file paths against allowed/blocked path lists
- Prevents access to sensitive system directories

#### Command Injection Protection
- Blocks command injection patterns (`|`, `&`, `;`, `` ` ``, etc.)
- Validates package names and parameters
- Prevents execution of arbitrary commands

#### SQL Injection Protection
- Detects SQL injection patterns in input
- Validates database queries and parameters
- Prevents unauthorized database access

#### XSS Protection
- Blocks XSS patterns in input
- Validates HTML and script content
- Prevents cross-site scripting attacks

#### Package Name Validation
```rust
// Valid package names
"valid-package"     // ✅ Allowed
"package+plus"      // ✅ Allowed
"package.dot"       // ✅ Allowed

// Invalid package names
"package; rm -rf /" // ❌ Command injection
"../../../etc/passwd" // ❌ Path traversal
"<script>alert('xss')</script>" // ❌ XSS
```

### 2. Privilege Escalation Protection

#### Root Privilege Validation
- Validates root privileges for privileged operations
- Checks for proper privilege escalation methods
- Prevents unauthorized privilege escalation

#### Environment Security Checks
- Detects dangerous environment variables (`LD_PRELOAD`, `LD_LIBRARY_PATH`)
- Identifies container environments
- Validates execution context

#### Setuid Binary Detection
- Identifies setuid binaries in system
- Warns about potential security risks
- Monitors for privilege escalation vectors

#### World-Writable Directory Detection
- Identifies world-writable directories
- Warns about potential security risks
- Monitors file system security

### 3. Secure Communication

#### HTTPS Enforcement
- Requires HTTPS for all external communication
- Validates SSL/TLS certificates
- Prevents man-in-the-middle attacks

#### Source Validation
- Validates package sources against allowed list
- Blocks communication to malicious sources
- Ensures secure package downloads

#### D-Bus Security
- Implements proper D-Bus authentication
- Uses Polkit for authorization
- Restricts D-Bus access to authorized users

### 4. Security Scanning

#### Package Vulnerability Scanning
- Scans packages for known vulnerabilities
- Integrates with vulnerability databases
- Provides remediation recommendations

#### Malware Detection
- Scans packages for malware signatures
- Detects suspicious patterns
- Blocks malicious packages

#### File Size Validation
- Enforces maximum file size limits
- Prevents resource exhaustion attacks
- Validates package integrity

## Security Configuration

### Default Security Settings

```rust
SecurityConfig {
    enable_input_validation: true,
    enable_privilege_protection: true,
    enable_secure_communication: true,
    enable_security_scanning: true,
    allowed_paths: [
        "/var/lib/apt-ostree",
        "/etc/apt-ostree", 
        "/var/cache/apt-ostree",
        "/var/log/apt-ostree"
    ],
    blocked_paths: [
        "/etc/shadow",
        "/etc/passwd", 
        "/etc/sudoers",
        "/root",
        "/home"
    ],
    allowed_sources: [
        "deb.debian.org",
        "archive.ubuntu.com",
        "security.ubuntu.com"
    ],
    max_file_size: 100 * 1024 * 1024, // 100MB
    max_package_count: 1000,
    security_scan_timeout: 300 // 5 minutes
}
```

### Customizing Security Settings

#### Environment Variables
```bash
# Disable input validation (not recommended)
export APT_OSTREE_DISABLE_INPUT_VALIDATION=1

# Custom allowed paths
export APT_OSTREE_ALLOWED_PATHS="/custom/path1,/custom/path2"

# Custom blocked sources
export APT_OSTREE_BLOCKED_SOURCES="malicious.example.com"
```

#### Configuration File
```ini
# /etc/apt-ostree/security.conf
[security]
enable_input_validation = true
enable_privilege_protection = true
enable_secure_communication = true
enable_security_scanning = true

[paths]
allowed = /var/lib/apt-ostree,/etc/apt-ostree
blocked = /etc/shadow,/etc/passwd

[sources]
allowed = deb.debian.org,archive.ubuntu.com
blocked = malicious.example.com

[limits]
max_file_size = 104857600
max_package_count = 1000
security_scan_timeout = 300
```

## Security Commands

### Security Report
```bash
# Generate comprehensive security report
apt-ostree security --report

# Output includes:
# - System security status
# - Configuration status
# - Validation cache statistics
# - Security recommendations
```

### Input Validation
```bash
# Validate input for security
apt-ostree security --validate "package-name"

# Returns:
# - Validation result (pass/fail)
# - Security score (0-100)
# - Specific errors and warnings
```

### Package Scanning
```bash
# Scan package for vulnerabilities
apt-ostree security --scan /path/to/package.deb

# Returns:
# - Vulnerability list
# - Severity levels
# - Remediation recommendations
```

### Privilege Protection
```bash
# Check privilege escalation protection
apt-ostree security --privilege

# Returns:
# - Protection status
# - Security warnings
# - Recommendations
```

## Integration with Existing Commands

### Automatic Security Validation
All privileged commands automatically include security validation:

```bash
# Package installation with security validation
apt-ostree install package-name

# Security checks performed:
# - Package name validation
# - Path validation
# - Privilege escalation protection
# - Input sanitization
```

### Security Logging
All security events are logged with structured logging:

```json
{
  "timestamp": "2024-12-19T10:30:00Z",
  "level": "WARN",
  "security_event": "input_validation_failed",
  "input": "malicious-input",
  "validation_type": "package_name",
  "errors": ["Command injection attempt detected"],
  "security_score": 0
}
```

## Security Best Practices

### 1. Regular Security Updates
- Keep APT-OSTree updated to latest version
- Monitor security advisories
- Apply security patches promptly

### 2. Configuration Security
- Use secure configuration files
- Restrict access to configuration directories
- Validate configuration changes

### 3. Network Security
- Use HTTPS for all external communication
- Validate package sources
- Monitor network traffic

### 4. File System Security
- Restrict access to sensitive directories
- Use proper file permissions
- Monitor file system changes

### 5. Process Security
- Use bubblewrap sandboxing for scripts
- Implement proper privilege separation
- Monitor process execution

## Security Monitoring

### Security Metrics
- Input validation success/failure rates
- Security scan results
- Privilege escalation attempts
- Malicious input detection

### Security Alerts
- Failed security validations
- Detected vulnerabilities
- Privilege escalation attempts
- Malicious package detection

### Security Reporting
- Daily security reports
- Vulnerability summaries
- Security incident reports
- Compliance reports

## Compliance and Standards

### Security Standards
- OWASP Top 10 compliance
- CWE/SANS Top 25 compliance
- NIST Cybersecurity Framework
- ISO 27001 security controls

### Audit Trail
- Complete security event logging
- Audit trail preservation
- Compliance reporting
- Incident investigation support

## Troubleshooting

### Common Security Issues

#### Input Validation Failures
```bash
# Error: Input validation failed
# Solution: Check input for malicious patterns
apt-ostree security --validate "your-input"
```

#### Privilege Escalation Warnings
```bash
# Warning: Privilege escalation protection active
# Solution: Ensure proper authentication
sudo apt-ostree install package-name
```

#### Security Scan Failures
```bash
# Error: Security scan timeout
# Solution: Increase timeout or check network
export APT_OSTREE_SECURITY_SCAN_TIMEOUT=600
```

### Security Debugging
```bash
# Enable security debugging
export RUST_LOG=apt_ostree::security=debug

# Run with security debugging
apt-ostree install package-name
```

## Future Security Enhancements

### Planned Features
- Real-time vulnerability scanning
- Machine learning-based threat detection
- Advanced malware detection
- Security automation and response

### Integration Opportunities
- Integration with security information and event management (SIEM)
- Vulnerability database integration
- Security orchestration and response (SOAR)
- Compliance automation

## Conclusion

APT-OSTree provides comprehensive security hardening through multiple layers of protection. The security system is designed to be:

- **Comprehensive**: Covers all major attack vectors
- **Configurable**: Adaptable to different security requirements
- **Transparent**: Clear logging and reporting
- **Maintainable**: Easy to update and extend

The security features ensure that APT-OSTree can be safely deployed in production environments while maintaining the flexibility and functionality required for modern system management. 