Application Whitelisting - Definition & Overview

What is Application Whitelisting?

Application whitelisting, also referred to as application allowlisting, is a security control used to regulate which software applications are permitted to run within a system or network. It is commonly used to enforce strict execution policies and maintain control over application usage across endpoints.

This approach is widely adopted in enterprise environments where preventing unauthorized software execution and maintaining consistent system behaviour are key security priorities.

How Does Application Whitelisting Work?

Application whitelisting works by allowing only explicitly approved applications to run on a system, while blocking all others by default. Administrators create and maintain a list of trusted software that is permitted to execute within the environment. Any application that does not match this approved list is automatically prevented from running.

Whitelisting policies can be defined using multiple attributes, such as file names, cryptographic hashes, digital signatures, or trusted publishers. In more advanced implementations, these policies may also include supporting components like libraries and configuration files to ensure legitimate applications function without interruption.

Application whitelisting can be enforced through native operating system controls or through centralized endpoint security platforms. Once enabled, the solution continuously validates applications at runtime, ensuring that only authorized software executes. This approach reduces exposure to malware, unauthorized tools, and accidental execution of unapproved code, while maintaining consistent control across endpoints.

Methods of Application Whitelisting

Application whitelisting relies on different methods to determine whether an application is authorized to run. These methods are based on identifying specific attributes of a file and are often combined to strengthen protection and reduce the risk of malware execution.

• File Name
• File Path
• File ize
• Digital Signature/Publisher
• Cryptographic Hash

File Name

File name whitelisting compares the executable’s name against an approved list. While simple to implement, this method is vulnerable to abuse, as malicious files can be renamed to match trusted applications.

File Path

File path whitelisting validates applications based on their location within the system. Policies may apply to a specific directory or a full file path. Although more restrictive than file name matching, this method can still be bypassed if malicious files are placed in trusted directories.

File Size

File size whitelisting checks whether an executable matches an approved size. Because file size can change easily and offers limited assurance on its own, it is typically used only as a supplementary control alongside other methods.

Digital Signature or Publisher

Digital signature-based whitelisting verifies whether an application is signed by a trusted publisher. If the publisher is approved, applications signed by them, including updates, are allowed to run. While scalable and efficient, this method assumes the publisher’s software has not been compromised.

Cryptographic Hash

Cryptographic hash whitelisting uses a unique hash value generated from an application file to confirm its integrity. Any change to the file results in a different hash, making this method highly precise. However, updates or modifications require the hash to be regenerated and reapproved.

Application Whitelisting vs Blacklisting

Application whitelisting and application blacklisting are two contrasting approaches used to control which software is allowed to run within an environment. Both aim to reduce security risks, but they differ significantly in how control is enforced.

Application whitelisting follows a deny-by-default model. Only applications that are explicitly approved are allowed to execute, while all others are blocked automatically. This approach offers stronger protection against malware, zero-day threats, and unauthorized software, as unknown or untrusted applications are prevented from running regardless of whether they are already identified as malicious.

Application blacklisting, in contrast, operates on an allow-by-default model. All applications are permitted to run except those that appear on a list of known malicious or unwanted software. While easier to deploy and manage initially, blacklisting depends heavily on continuous updates and signature databases, making it less effective against new or unknown threats.

From a security perspective, whitelisting provides tighter control and is commonly used in high-security or regulated environments. Blacklisting, while still useful as a complementary control, offers broader flexibility but lower assurance when used alone.