Block Listing

Definitions

1. A security approach that denies a known set of bad items such as IPs, domains, files, or commands while allowing everything else by default. Block listing is easier to maintain than allowlisting in dynamic environments, but it is also easier for attackers to evade.

   In plain English: Blocking known bad items while allowing everything else.

   Example: "The mail gateway relied on block listing malicious domains, but the attackers kept rotating infrastructure faster than rules were updated."

Related Terms

• Administrative Privilege
• Allowlist
• Application Control
• Application Whitelisting
• BYOD Security
• Data Governance Security
• Database Firewall
• Deny by Default
• Emergency Access
• Geofencing Security
• Object Storage Security
• Port Security
• Proxy Security
• Restriction
• Authorization Policy