The Top 20 Critical Controls for Effective Cyber Defense have been around for half a decade now, and are constantly gaining more praise and acceptance among information security groups and government organizations across the globe. One of the main reasons for this is that all of these controls have been shown to stop or mitigate known, real-world attacks. Another reason for their success is that they are constantly being updated and adjusted to fit the changing threat picture as it emerges. 

One of these recent updates is the delineation of the “First Five” from the other “Quick Wins” category of sub-controls included in the guidance (Quick Wins security controls are those that provide solid risk reduction without major procedural, architectural or technical changes to an environment, or that provide substantial and immediate risk reduction against very common attacks – in other words, these are the controls that give you the most bang for the buck). The First Five Quick Wins controls are those that have been shown to be the most effective means yet to stop the targeted intrusions that are doing the greatest damage to many organizations. They include:

1. Application white listing: Application white listing technology only allows systems to run software applications that are included in the white list. This control prevents both external and internal attackers from implementing malicious and unwanted applications on the system. One caveat that should be kept in mind is that the organization must strictly control access to and modifications of the white list itself. New software applications should be approved by a change control committee and access/changes to the white list should be strictly monitored.
2. Secure standard images: Organizations should employ secure standard images for configuring their systems. These standard images should utilize hardened versions of underlying operating systems and applications. It is important to keep in mind that these standard images need to be updated and validated on a regular basis in order to meet the changing threat picture.
3. Automated patching tools and processes: Automated patching tools, along with appropriate policies and procedures, allow organizations to close vulnerabilities in their systems in a timely manner. The standard for this control is patching of both application and operating system software within 48 hours of release.
4. Removal or replacement of outdated software applications: Many computer networks we test have outdated or legacy software applications present on the system. Dated software applications may have both known and previously undiscovered vulnerabilities associated with them, and are consequently very useful to cyber attackers. Organizations should have mechanisms in place to identify then remove or replace such vulnerable applications in a timely manner just as is done with the patching process above.
5. Control of administrative privileges and accounts: One of the most useful mechanisms employed by cyber attackers is elevation of privileges. Attackers can turn simple compromise of one client machine to full domain compromise by this means, simply because administrative access is not well controlled. To thwart this, administrative access should be given to as few users as possible, and administrative privileged functions should be monitored for anomalous behavior. MSI also recommends that administrators use separate credentials for simple network access and administrative access to the system. In addition, multi-part authentication for administrative access should be considered. Attackers can’t do that much damage if they are limited to isolated client machines!

Certainly, the controls detailed above are not the only security controls that organizations should implement to protect their information assets. However, these are the controls that are currently being implemented first by the most security-aware and skilled organizations out there. Perhaps your organization can also benefit from the lessons they have learned.

Thanks to John Davis for writing this post.