ISO 27001:2022 Annex A Control 8.23

Abstract of Control 8.23: Web filtering

ISO 27001 Annex A Control 8.23 Web filtering safeguards your network by regulating access to external websites. This action reduces exposure to malicious content and preserves confidentiality, integrity, and availability. You maintain a well-structured online environment, and your users stay shielded from potential threats.

Control Type

Information Security Properties

Cybersecurity Concepts

Operational Capabilities

Security Domains

Objective of ISO 27001 Control 8.23

Web filtering mitigates the risks of unauthorized or malicious website access. This approach stops malware and phishing attempts from reaching your systems. You strengthen your cybersecurity stance when you manage web access according to predefined rules.

Purpose of Implementing Web Filtering

Web filtering tackles two primary concerns: stopping malware from infiltrating your network and blocking access to prohibited resources. This strategy maintains system health and fosters responsible online behavior. You create a streamlined path for safe browsing and keep unwanted visitors out.

Core Components of Web Filtering

A few components will guide your implementation:

1. Website Categorization
Classify allowed and disallowed sites based on business purpose. Group sites by risk level, and create dedicated lists for permitted or forbidden access.

2. Technological Measures
Employ solutions that rely on signatures and heuristics, then supplement them with whitelists and blacklists. Some configurations detect unusual behavior on the fly and respond by blocking the relevant source.

3. Rules for Web Access
Develop guidelines that define what users can and cannot do online. Consider the specific needs of each business unit. Prompt users to follow approved processes if they must access a restricted site.

4. Training for Safe Browsing
Offer interactive sessions that highlight secure online practices. Show employees how to identify phishing attempts, and walk them through best practices for handling browser warnings. Encourage questions: have you informed your users about these policies?

5. Ongoing Monitoring
Check web usage patterns and gauge the effectiveness of your filtering measures. Adjust settings if you see unusual traffic or evolving threats. Gather feedback from IT staff to refine rules and keep your network clean.

Techniques for Effective Web Filtering

Web filtering involves using various methods to block or restrict access to harmful or non-compliant websites. Below are the core techniques you can employ:

Signatures
This technique matches web traffic to known malicious patterns. By using signature databases, you can automatically block access to websites linked to malware, phishing, or other harmful content.
Heuristics
Analyze website behavior to detect unusual or suspicious activity. Unlike signatures, heuristics can identify emerging threats that don’t yet have a signature, offering a proactive layer of protection.
Whitelists
Allow access only to a predefined list of trusted websites. This is particularly effective in environments requiring strict security, ensuring users can only visit approved and secure sites.
Blacklists
Block websites that are flagged as harmful or non-compliant. These lists are regularly updated to include known malicious domains, preventing access to high-risk online resources.
Custom Configurations
Tailor your web filtering rules to your organization’s specific needs. This might include allowing access to certain categories of sites for specific departments while restricting access elsewhere. Evolving threats can also be addressed by periodically updating your configurations.

Training and Awareness

Your organization should implement comprehensive training programs that cover the following:

Rules for Online Resource Usage
Educate employees about your policies regarding internet access. This includes explaining which websites are permitted, restricted, or require special approval.
Steps for Accessing Restricted Web Resources
Provide clear instructions for requesting access to restricted websites when business needs arise. Ensure users know how to initiate exception processes and gain approval efficiently.
Adhering to Browser Security Advisories
Teach employees to respect browser security warnings. If a browser flags a website as insecure, users should not override the warning without consulting your security team.
Contact Points for Concerns or Exceptions
Ensure employees know where to go for help with web filtering issues. Provide a dedicated contact point or help desk for raising concerns, reporting blocked legitimate sites, or seeking exceptions.

Relevant ISO 27001 Controls

Control 8.23 its effectiveness is enhanced when aligned with other ISO 27001 controls.

Control 5.7 Threat Intelligence
Incorporate intelligence on malicious websites and domains to refine your filtering measures and stay ahead of evolving threats.
Control 5.22 Monitoring and Review
Continuously evaluate your web filtering system to ensure it remains effective. Monitor usage trends and identify areas for improvement.
Control 5.8 Information Security in Project Management
Address web-based risks in the context of project environments, particularly for team members accessing online resources.
Control 6.3 Awareness and Training
Reinforce secure browsing habits and increase awareness of online threats through targeted training programs.
Control 8.28 Secure Coding
Maintain optimal configurations for browsers and systems to support web filtering efforts effectively.

Templates Useful for Implementing Control 8.23

When implementing web filtering as part of your ISO 27001 compliance, having the right templates can simplify the process and ensure consistency across your organization. Below are templates that can support this control effectively:

Web Filtering Policy Template
This template outlines the rules and procedures for managing access to external websites. It includes sections for acceptable use, blocked categories, exception processes, and enforcement methods.
Training and Awareness Plan Template
Use this template to design a comprehensive training program for employees. It includes details on session topics, delivery methods, scheduling, and feedback mechanisms to ensure all personnel understand and adhere to web filtering policies.
Exception Request Form Template
This form helps users request access to restricted websites for legitimate business needs. It includes fields for website details, justification, department approval, and IT/security review.
Monitoring and Review Checklist
A checklist template to ensure regular monitoring of web filtering effectiveness. It includes items such as reviewing logs, updating blacklists/whitelists, and evaluating filtering tool configurations.
Threat Intelligence Integration Template
This template assists with integrating threat intelligence sources into your web filtering solution. It covers how to gather, review, and apply intelligence data to refine filtering measures.
Incident Management Template
If a web filtering failure leads to a security incident, this template provides a clear action plan for mitigating the impact. It includes response procedures, roles, and communication protocols.
User Acknowledgment Form
Use this template to document employee acknowledgment of web filtering policies and training completion. It demonstrates that personnel are informed about the rules and responsibilities regarding online resource usage.