Chapter 6: Security & Risks
Security considerations and risk management strategies
6.1 Common Security Threats
Understanding the threat landscape is essential for designing effective security controls. Modern network environments face a wide range of threats that evolve constantly as attackers develop new techniques and exploit emerging vulnerabilities.
External Threats
| Threat Type | Description | Impact | Mitigation |
|---|---|---|---|
| DDoS Attacks | Distributed denial of service overwhelming network resources | Service unavailability, revenue loss | DDoS protection service, rate limiting, traffic scrubbing |
| Ransomware | Malware that encrypts data and demands payment | Data loss, business disruption, financial loss | Backup and recovery, endpoint protection, user training |
| Phishing | Social engineering to steal credentials or install malware | Account compromise, data breach | Email filtering, user awareness training, MFA |
| Zero-Day Exploits | Attacks targeting unknown vulnerabilities | System compromise, data exfiltration | IPS, sandboxing, virtual patching, threat intelligence |
Internal Threats
- Insider Threats: Malicious or negligent employees with authorized access causing data breaches or sabotage
- Misconfiguration: Improperly configured security controls creating vulnerabilities and exposing systems
- Shadow IT: Unauthorized applications and services bypassing security controls
- Weak Passwords: Easily guessed or reused passwords enabling unauthorized access
6.2 Risk Assessment and Management
Risk assessment is a systematic process of identifying, analyzing, and evaluating security risks to determine appropriate mitigation strategies. Effective risk management balances security requirements with business objectives and resource constraints.
Risk Assessment Process
- Asset Identification: Catalog all critical assets including systems, data, and applications
- Threat Identification: Identify potential threats relevant to each asset
- Vulnerability Assessment: Discover weaknesses that could be exploited by threats
- Impact Analysis: Determine potential business impact if threats materialize
- Likelihood Assessment: Estimate probability of each threat occurring
- Risk Calculation: Calculate risk level as function of impact and likelihood
- Mitigation Planning: Develop strategies to reduce, transfer, accept, or avoid risks
Risk Matrix
| Likelihood \ Impact | Low | Medium | High | Critical |
|---|---|---|---|---|
| Very Likely | Medium | High | Critical | Critical |
| Likely | Low | Medium | High | Critical |
| Possible | Low | Low | Medium | High |
| Unlikely | Low | Low | Low | Medium |
6.3 Security Best Practices
Implementing security best practices reduces the attack surface and strengthens the overall security posture. These practices should be applied consistently across all systems and regularly reviewed for effectiveness.
Configuration Hardening
- Change Default Credentials: Replace all default usernames and passwords immediately after installation
- Disable Unnecessary Services: Turn off unused protocols, ports, and services to reduce attack surface
- Enable Logging: Configure comprehensive logging for all security events and system activities
- Apply Security Patches: Maintain current patch levels for all systems and applications
- Implement Least Privilege: Grant minimum necessary permissions to users and services
Network Security Controls
| Control | Purpose | Implementation |
|---|---|---|
| Network Segmentation | Isolate sensitive systems and limit lateral movement | VLANs, firewalls, access control lists |
| Encryption | Protect data confidentiality in transit and at rest | TLS/SSL, IPsec VPN, disk encryption |
| Multi-Factor Authentication | Strengthen authentication beyond passwords | TOTP tokens, SMS codes, biometrics |
| Intrusion Prevention | Detect and block malicious traffic | NGFW IPS, network-based IDS/IPS |