What is Application Whitelisting (Safelisting)

Learning objectives
  • Learn the way application safelisting works
  • Explore the benefits of application safelisting
  • Understand the difference between safelisting and blocklisting

When you have several users with business computers, it’s important for the security of your organization to allow only approved applications to be installed on corporate machines. Using an application safelist, users can determine if their software of choice can be installed on their business machine and install it freely, but all others are blocked. Security professionals, network administrators, and other operations people determine the software added to the safelist to improve security on corporate machines. The purpose of an application safelist is to secure the network and corporate machines, and protect your data from being breached.

How does application safelisting work?

For personal computers, individuals can install any application without affecting other computers. In a corporate environment, any computer or device connected to the network could cause serious cybersecurity problems for other devices and infrastructure. Malware running on the device could copy itself to the corporate network, ransomware could scan the network and encrypt sensitive files, or a hijacked device could allow an attacker to access private resources. When users can install any application on their computers, it opens risks that could be exploited by threat actors.

Small businesses usually allow users to install any application, but eventually network administrators experience difficulties with bugs and issues from malware. They then form an application safelist used to control applications installed on a computer. Desktops and laptops can be locked down so that only administrators can install software, and a safelist provides guidance to administrators when they need to know if a user installation request can be satisfied.

Modern operating systems such as Windows have tools built in that allow administrators to safelist application installations. For example, Windows AppLocker can be used to allow only specific applications approved by network administrators. Administrators can also lock computers down based on version, file names, installation paths and file size.

The application safelist is kept in a centralized location where administrators and users can look up the list of approved applications and request that administrators install a specific one. In some environments, users can install applications on their computers themselves provided the application is on the centralized safelist.

Safelisting software controls much more than just applications. Users need access to scripts, browser plugins, macros, libraries, configuration files, and registry settings and safelisting software will handle all these factors for administrators. The list must also be updated whenever a new version must be installed on desktops, and administrators can clear applications for approval after they are thoroughly tested for any bugs or vulnerabilities.

What is the difference between application safelisting and blocklisting?

Safelisting is the preferred way to block applications from being installed on corporate machines. It allows only applications on the list, but a safelist requires a lot of overhead from administrators who must constantly keep the list updated. You might consider a blocklisting approach instead. 

A blocklisting approach is less overhead for administrators, but it isn’t as secure as safelisting. Blocklisting lets users install any application provided it’s not on the central block list. To properly set up a blocklist, administrators would need to know of every malicious application, file, configuration and registry value that could negatively impact the computer and network. If administrators miss an application, it can be installed on the computer and leaves it vulnerable to the latest malware.

For the best security, safelisting is preferred even if it requires more staff overhead. It ensures that only secure applications can be installed, and anything outside of the list cannot be installed. Safaelisting has the best defense against malware, malicious settings and macros, and incorrect configurations, so it’s the preferred approach. 

What are the benefits of application safelisting?

The best benefit of application safelisting is its defense against malware including ransomware. Should users accidentally execute a malicious file or run a malicious macro, any copying or installation of files would be rejected by the operating system. You could use AppLocker in Windows, but third-party software has additional features such as notifications that can be sent to administrators when a malicious application is blocked from running on the desktop.

Cybersecurity best practices require antivirus software installed on all network devices. Antivirus software must be constantly updated and patched to detect the latest malware. Many antivirus applications use artificial intelligence (AI), but even the best antivirus occasionally has false negatives. A false negative will allow malware to access the operating system and install itself on the user’s device.

To add to your cybersecurity, application safelisting takes over for an antivirus false negative. If the antivirus application does not stop malware from being installed, the safelist will stop it instead. If you use a third-party application to perform your safelisting, administrators can run reports, get alerts when malware is blocked, identify computers that could be compromised, and identify common software blocked by the safelisting software. The result is that administrators have a better understanding of the applications and malware run by users, and these users can be better educated on cybersecurity and common malware.

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