Wednesday, October 12, 2022

Firewall Review

Following are the points you can consider while performing a manual firewall (Configuration and Rulebase) review:

1. Firmware & Patches

  • OS Security patches are updated
  • Device placed in secure place with Access Control

2. SNMP version (should be v3) & Community String (should be strong)

3. Identity & Authentication

  • Default user names and passwords are changed
  • Firewall is authenticated with RADIUS or TACACS
  • External access through secure VPN
  • Verify VPN encryption uses strong algorithms (AES etc.)

4. Check for session timeout (Console, Inactivity timeout)

5. High Availability & BCP DR Testing

  • High Availability with a secondary firewall
  • BCP DR testing is performed at regular intervals

6. Config. backup, Logs, Alerts & NTP Server

  • Firewall config file and rule base is backed up
  • Logs are collected and alerts are configured
  • NTP server is configured (Good to have a set of private NTP servers in sync with a public NTP server)

7. Insecure access rule - "ANY" rule

  • Check for "deny-all" setting if it is configured at the end of every rule set

8. Access to vulnerable ports

  • Access from DMZ to internal network and vice-versa
  • Direct access from internet to internal network

9. Access to large subnets

10. Redundant, Shadow, Unused & Inactive rules

11. Remove unused objects

12. Critical port access rules

  • Mostly access will be provided using PIM and PAM solutions, so check for the need of such rules (port 22, 1433, 3389 etc.)

13. Change Management

  • Make any changes to firewall or it's rule base via proper change management

Happy Learning !!

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