Web Filtering Configuration

Web filtering restricts user access to external websites based on specific criteria to protect systems. DNS filtering blocks requests at the domain resolution level, while URL filtering inspects the full web address path for more granular control.

Common security control expectations require organizations to manage access to external websites to reduce exposure to malicious content. This typically involves implementing technical controls to filter, monitor, and block harmful domains and categories, while keeping evidence that controls are operating as intended.

Deploy DNS filtering, URL blocklists, secure web gateways, web proxies, or endpoint security tools that enforce access policies across your organization. Ensure the configuration is applied consistently to in-scope users and devices, and retain configuration exports and logs that demonstrate enforcement.

The policy should define acceptable use rules, specify categorically blocked sites like malware or phishing, outline the exception request process, and detail how filtering rules are technically enforced and periodically reviewed by management.

For strict security compliance, organizations must block known malware distributors, phishing sites, botnet command-and-control servers, illegal content repositories, and anonymizer services that bypass network security monitoring.

Exceptions must follow a documented approval workflow requiring clear business justification, managerial sign-off, a strictly defined expiration date, and periodic access reviews to ensure the temporary access is still necessary and justified.

While SSL/TLS inspection allows deeper visibility into encrypted traffic, it introduces significant privacy risks and performance overhead. DNS filtering and endpoint-level categorization serve as highly effective alternatives without breaking native encryption.

Enforce remote filtering using cloud-based secure web gateways, endpoint security agents installed directly on the device, or always-on VPNs that route external internet traffic through your web filtering infrastructure when appropriate.

Retain system block logs, threat prevention dashboard reports, configuration exports showing active blocked categories, and exception approval tickets. Auditors review these to verify the technical controls are actively functioning.

Conduct regular tests by attempting to access safe test resources such as EICAR or standardized blocking URLs, capturing screenshots of the resulting block pages, and verifying the associated alert generation in your centralized logging system.