A whitelist is a list of email addresses, IP addresses, or applications that are deemed safe and allowed to run or be seen on a device or network. Where blacklists only block items on the list, whitelists are similar to a VIP list and only allow entry to the items on that list. They are both often used as cybersecurity measures.
Common uses of whitelisting
- Email: Perhaps the most popular use for whitelisting is for blocking spam and phishing attempts from an email inbox by creating a safe senders list. This ensures that emails from senders you want to see don t end up in a spam folder, and spam emails don t show up in your inbox.
- IP Addresses: IP whitelisting is used to grant network access only to certain IP addresses. While this has been used as a security measure, it does have its drawbacks. First of all, IP addresses are not constant and can change often. Second, IP addresses can be spoofed using a VPN and can cause your network to become less secure.
- Applications: Application whitelisting refers to whitelisting only trusted and secure applications on a device. The ability to whitelist applications is usually added onto an OS. This practice is often used on employee computers that are monitored by an administrator to keep the network safe and employees from downloading apps that might inhibit productivity. Application whitelisting also poses the risk of an attacker replacing a whitelisted application with a malicious one by ensuring they have the same specifications. You can take additional security steps by applying cryptographic hashing.
Note: In recent years, prominent members of the computing industry have started to shift away from using the terms whitelist and blacklist because of their negative connotation and have instead shifted to allowlist/denylist or passlist/blocklist.