Application allowlisting and application blocklisting are two methods of application control that organizations can use to enhance their security posture. Each method has its benefits and challenges, and the decision to implement one or both of these strategies depends on an enterprise’s specific needs and use cases.
Application allowlisting is a security control that only permits preapproved applications and processes to run. It also allows these applications to access only pre-identified files. In addition to managing which applications can run, allowlists also manage which users and devices have permission to access a given service or application. This approach minimizes the attack surface by only allowing authorized applications to execute.
However, creating and maintaining an optimal allowlist can be challenging. An overly permissive or simplistic allowlist without sufficient oversight can expand the attack surface and introduce undue risk. On the other hand, an excessively strict or faulty allowlist can prevent users from accessing legitimate applications they need for their jobs, which can hurt productivity. Despite these challenges, application allowlisting has direct applicability in unique or special-purpose systems, such as ATMs or smart meters, where devices have specific functions. In such cases, allowlisting allows only relevant apps and processes to execute.
Application allowlisting offers operational benefits beyond threat protection. These include application inventory, which helps identify unauthorized applications and incorrect versions of approved applications. It also includes file integrity monitoring, which involves periodically checking for changes to application files on disk. Finally, application allowlisting can aid in malware detection during incident response by scanning for attributes of malicious files across the entire enterprise.
To maximize the benefits of allowlisting, organizations often follow NIST Special Publication 800-167, “Guide to Application Whitelisting.” This guidance recommends using multiple attributes in conjunction with each other to allowlist applications. These attributes include file path, file name, file size, digital signature, and cryptographic hash.
On the other hand, application blocklisting takes the opposite approach to application control. It prevents anything known to be malicious from running on endpoints or servers in a network. Instead of allowing specific applications, a blocklist bans specific devices from accessing a service or application. This approach has been widely used as a staple of the cybersecurity arsenal for years in tools like antimalware, intrusion prevention and detection systems, and email filtering systems.
However, blocklisting has its challenges. The list of threats to block is constantly growing and evolving, making it difficult to keep track of all known malicious programs and potentially unwanted applications. Moreover, a blocklist cannot account for unknown threats, leaving the organization vulnerable to zero-day attacks.
In practice, many organizations find it most pragmatic to combine both application allowlisting and blocklisting. By using both strategies, organizations can selectively allow applications, processes, and files while also blocking known malicious applications and files. This combination provides a comprehensive approach to application control that is adaptable to the ever-changing security attack landscape.
In response to increasing awareness around diversity, equity, and social justice, the terms “whitelisting” and “blacklisting” have been reassessed to adopt more inclusive language. The terms “allowlisting” and “blocklisting” have been adopted to remove racial and cultural connotations and better describe the functionalities of these strategies. TechTarget, as a media outlet and part of the tech industry, is actively responding to readers’ concerns and cultural changes by adopting more inclusive language whenever possible.
In conclusion, application allowlisting and application blocklisting are two methods of application control that organizations can use to enhance their security posture. Each method has its benefits and challenges, and a combination of both strategies is often the most pragmatic approach. Implementation decisions should be based on an enterprise’s specific needs and use cases, with a focus on minimizing the attack surface and protecting against known threats while also accounting for unknown threats.