Infrastructure & Network Security

Firewall Rule Review and Optimization

  • May 9, 2025
  • 0

Sherlocked Security – Firewall Rule Review & Optimization

Reduce Attack Surface, Enhance Performance, and Align with Zero Trust Principles

1. Statement of Work (SOW)

Service Name: Firewall Rule Review & Optimization
Client Type: Enterprises, Critical Infrastructure, Financial Institutions, SaaS Providers
Service Model: Project-Based Engagement or Periodic Review as a Retainer Service
Compliance Alignment: PCI-DSS, NIST 800-41, ISO/IEC 27001, CIS Controls, HIPAA

Firewall Rule Review & Optimization Covers:

  • Audit of firewall policies, rules, and objects
  • Elimination of redundant, obsolete, or shadowed rules
  • Alignment of rulebase with least privilege and Zero Trust principles
  • Performance impact analysis and tuning
  • Review of logging and alerting configurations
  • Application and user-aware rule evaluation (where supported)
  • Firewall rule recertification process design
  • Integration with compliance and change control processes

2. Our Approach

[Rulebase Collection] → [Policy Audit] → [Redundancy & Risk Detection] → [Usage Analysis] → [Optimization Planning] → [Compliance Mapping] → [Recommendations & Implementation]

3. Methodology

  • Rulebase Extraction: Securely collect firewall rulesets from supported platforms (e.g., Palo Alto, Fortinet, Cisco ASA, Check Point).
  • Redundancy & Shadowing Analysis: Identify overlapping, unused, or conflicting rules that increase risk or complexity.
  • Access Scope Validation: Validate if rules adhere to least privilege by evaluating source/destination/service combinations.
  • Usage Analytics: Use firewall logs to determine rule usage, application context, and effectiveness.
  • Object & Group Review: Audit object definitions, nested groups, and dynamic lists for clarity and efficiency.
  • Risk-Based Tagging: Categorize rules based on exposure, business criticality, and threat potential.
  • Compliance Check: Evaluate against PCI-DSS, NIST 800-41, and organizational policies.
  • Optimization Plan: Deliver recommendations for rule cleanup, reordering, consolidation, and hardening.
  • Rule Recertification Strategy: Propose a continuous review process for stale or unauthorized rules.

4. Deliverables to the Client

  1. Firewall Rule Audit Report: Detailed findings on risky, unused, or overly permissive rules.
  2. Optimization Recommendations: A prioritized list of rules to remove, merge, or modify.
  3. Risk Exposure Map: Visualization of rules that pose high risk or open unnecessary ports/zones.
  4. Compliance Gap Analysis: Identification of rule-related non-compliance with regulatory frameworks.
  5. Rule Usage & Hit Count Summary: Analysis of rule activity over time to support cleanup decisions.
  6. Object/Group Cleanup Plan: Recommendations for simplifying object libraries and rule references.
  7. Firewall Rule Governance SOP: Guide for rule review cadence, approval workflows, and change control integration.

5. What We Need from You (Client Requirements)

  • Firewall Rulebase Export: Secure export of current rule sets (read-only access or config files).
  • Platform Information: Version and vendor details (e.g., Fortinet v6.4, Palo Alto PAN-OS 10.x).
  • Traffic Logs (Optional): Firewall hit counts, log exports, or API access for usage analysis.
  • Network Diagram: To contextualize rule placements and zone design.
  • Security Policy Documents: Network security and segmentation policies.
  • Change History (Optional): Rule change logs or audit trail (if available).

6. Tools & Technology Stack

  • Firewall Vendors Supported:

    • Palo Alto Networks, Fortinet, Cisco ASA/Firepower, Check Point, Juniper SRX, SonicWall

  • Analysis Tools:

    • FireMon Security Manager
    • Tufin SecureTrack
    • AlgoSec Firewall Analyzer
    • Nipper Studio (Titania)
    • Custom Python/Ansible scripts for rule parsing

  • Visualization:

    • Draw.io, Lucidchart, FireMon Policy Map, Custom heat maps

  • Compliance Reference:

    • NIST 800-41, PCI-DSS Req 1.1.x, CIS Benchmarks, ISO/IEC 27001 Annex A.13

7. Engagement Lifecycle

  1. Kickoff & Access Coordination: Define scope, gather rulebase exports, and discuss change control boundaries.
  2. Rulebase & Object Collection: Retrieve configurations and parse for analysis.
  3. Risk & Usage Review: Evaluate based on rule exposure, hit counts, and business justification.
  4. Optimization Recommendations: Provide cleanup list with justification and impact analysis.
  5. Compliance Mapping: Align rules to regulatory and internal policy frameworks.
  6. Review Meeting: Present findings to firewall administrators, security leads, and compliance teams.
  7. Remediation Support (Optional): Assist with implementation planning and validation.

8. Why Sherlocked Security?

Feature Sherlocked Advantage
Deep Vendor Expertise Certified experts in Palo Alto, Fortinet, Cisco, Check Point
Automated & Manual Review Combines tool-based scanning with manual validation
Risk-Oriented Optimization Rule tuning based on actual usage and exposure
Compliance-Focused Mapped to PCI, NIST, ISO, and custom enterprise frameworks
Operational Efficiency Improves firewall performance and simplifies change management

9. Real-World Case Studies

Financial Institution – Firewall Rulebase Cleanup

Client: A multi-branch bank with complex rulebase (12,000+ rules).
Findings: Over 60% of rules were unused or duplicated across zones.
Outcome: Reduced rulebase size by 52%, improved performance, and passed PCI audit with zero firewall-related findings.

SaaS Provider – Least Privilege Hardening

Client: Cloud-based app provider using Palo Alto NGFWs across data centers.
Findings: Multiple broad "any-any" service rules allowed lateral movement.
Outcome: Implemented app-aware rules, reduced attack surface, and created rule recertification workflows for DevOps.

10. SOP – Standard Operating Procedure

  1. Pre-Engagement Scoping

    • Define number of firewalls, platforms, and zones in scope
    • Identify business-critical segments (e.g., DMZ, PCI zones)

  2. Data Collection

    • Export current rulebase, object groups, and hit counts
    • Optionally integrate log data for behavioral analysis

  3. Static Rule Analysis

    • Detect unused, shadowed, and conflicting rules
    • Evaluate overly broad or legacy rules

  4. Dynamic Usage Review

    • Analyze hit counts and traffic patterns to validate rule necessity
    • Tag rules by risk and exposure level

  5. Optimization Planning

    • Recommend rule removal, merging, ordering, and object simplification
    • Include impact assessment for each recommendation

  6. Compliance & Governance Integration

    • Map findings to policy and regulatory requirements
    • Recommend rule lifecycle governance and recertification cadence

  7. Reporting & Review

    • Deliver findings in technical and executive-friendly formats
    • Host walkthrough session with IT/network/security teams

11. Firewall Review Readiness Checklist

1. Before Engagement

  • [ ] Identify firewalls/platforms in scope
  • [ ] Export current rulebases (config or XML format)
  • [ ] Provide network diagrams/zones context
  • [ ] Share existing policies (e.g., segmentation, access control)
  • [ ] Provide change management contacts and constraints

2. During Engagement

  • [ ] Validate rule coverage against known network segments
  • [ ] Identify unused or obsolete rules
  • [ ] Check for shadowed or duplicate rules
  • [ ] Review NAT and object definitions for clarity
  • [ ] Tag risky rules (e.g., ANY-ANY, overly permissive)
  • [ ] Map rules to business justification or services
  • [ ] Begin documentation for recertification strategy

3. After Engagement

  • [ ] Deliver risk-ranked optimization plan
  • [ ] Assist with remediation roadmap and scheduling
  • [ ] Provide compliance traceability matrix
  • [ ] Finalize governance SOP for future reviews
  • [ ] Recommend tools or automation to maintain hygiene

4. Continuous Improvement

  • [ ] Establish quarterly or biannual firewall reviews
  • [ ] Integrate rule changes with change control board
  • [ ] Train staff on least privilege and application-aware rule writing
  • [ ] Review object groups and rule performance routinely
  • [ ] Ensure audit readiness with documentation trails
Artifact Hunting & IOC Extraction
DDoS Testing & Mitigation Advisory