The Real Value of a Positive Control Model

During the last several years I’ve written a lot about the fact that Palo Alto Networks enables you to re-establish a network-based Positive Control Model from the network layer up through the application layer. But I never spent much time on why it’s important.

Today, I will reference a blog post by Jack Whitsitt, Avoiding Strategic Cyber Security Loss and the Unacceptable Offensive Advantage (Post 2/2), to help explain the value of implementing a Positive Control Model.

TL;DR: All information breaches result from human error. The human error rate per unit of information technology is fairly constant. However, because IT is always expanding (more applications and more functions per application), the actual number of human errors resulting in Vulnerabilities (used in the most general sense of the word) per time period is always increasing. Unfortunately, the information security team has limited resources (Defensive Capability) and cannot cope with the users’ ever increasing number of errors. This has created an ever growing “Offensive Advantage (Vulnerabilities – Defensive Capability).”  However, implementing a Positive Control Model to influence/control human behavior will reduce the number of user errors per time interval, which will reduce the Offensive Advantage to a manageable size.

On the network side Palo Alto Networks’ Next Generation Firewall monitors and controls traffic by user and application across all 65,535 TCP and UDP ports, all of the time, at specified speeds. Granular policies based on any combination of application, user, security zone, IP address, port, URL, and/or Threat Protection profiles are created with a single unified interface that enables the infosec team to respond quickly to new business requirements.

On the endpoint side, Trusteer provides a behavioral type of whitelisting that prevents device compromise and confidential data exfiltration. It requires little to no administrative configuration effort. Thousands of agents can be deployed in days. When implemented on already deployed Windows and Mac devices, Trusteer will detect compromised devices that traditional signature-based anti-virus products miss.

Let’s start with Jack’s basic truths about the relationships between technology, people’s behavior, and infosec resources. Cyber security is a problem that occurs over unbounded time. So it’s a rate problem driven by the ever increasing number of human errors per unit of time. While the number of human errors per unit of time per “unit of information technology” is steady, complexity, in the form of new applications and added functions to existing applications, is constantly increasing. Therefore the number of human errors per unit of time is constantly increasing.

Unfortunately, information security resources (technical and administrative controls) are limited. Therefore the organization’s Defense Capability cannot keep up with the increasing number of Vulnerabilities. Since the number of human errors increases at a faster rate than limited resource Defense Capacity, an Unacceptable Offensive Advantage is created. Here is a diagram that shows this.

offensiveadvantage1

What’s even worse, most Defensive controls cannot significantly shrink the gap between the Vulnerability curve and the Defense curve because they do not bend the vulnerability curve, as this graph shows.

offensiveadvantage2

So the only real hope of reducing organizational cyber security risk, i.e. the adversaries’ Offensive Advantage is to bend the Vulnerability curve as this graph shows.

offensiveadvantage3

Once you do that, you can apply additional controls to further shrink the gap between Vulnerability and Defense curves as this graph shows.

offensiveadvantage4

The question is how to do this. Perhaps Security Awareness Training can have some impact.

I recommend implementing network and host-based technical controls that can establish a Positive Control Model. In other words, only by defining what people are allowed to do and denying everything else can you actually bend the Vulnerability curve, i.e. reduce human errors, both unintentional and intentional.

Implementing a Positive Control Model does not happen instantly, i.e. it’s also is a rate problem. But if you don’t have the technical controls in place, no amount of process is going to improve the organization’s security posture.

This is why firewalls are such a critical network technical control. They are placed at critical choke points in the network, between subnets of different trust levels, with the express purpose of implementing a Positive Control Model.

Firewalls first became popular in the mid 1990s. At that time, when a new application was built, it was assigned a port number. For example, the mail protocol, SMTP was assigned port 25, and the HTTP protocol was assigned to port 80. At that time, (1) protocol and application meant the same thing, and (2) all applications “behaved,” i.e. they ran only on their assigned ports. Given this environment, all a firewall had to do was use the port numbers (and IP addresses) to control traffic. Hence the popularity of port-based stateful inspection firewalls.

Unfortunately, starting in the early 2000s, developers began writing applications to bypass the port-based stateful inspection firewall in order to get their applications deployed quickly in organizations without waiting for the security teams to make changes in policies. Also different applications were developed that could share a port like port 80 because it was always open to give people access to the Internet. Other techniques like port-hopping and encryption were used to bypass the port-based, stateful inspection firewall.

Security teams started deploying additional network security controls like URL Filtering to complement firewalls. This increase in complexity created new problems such as (1) policy coordination between URL Filtering and the firewalls, (2) performance issues, and (3) since URL Filtering products were mostly proxy based, they would break some of the newer applications frustrating users trying to do their jobs.

By 2005 it was obvious to some people that the application technology had obsoleted port-based firewalls and their helpers. A completely new approach to firewall architecture was needed that (1)  classified traffic by application first regardless of port, and (2) was backwardly compatible with port-based firewalls to enable the conversion process. This is exactly what the Palo Alto Networks team did, releasing their first “Next Generation” Firewall in 2007.

Palo Alto Networks classifies traffic at the beginning of the policy process by application. It monitors all 65,535 TCP and UDP for all applications, all of the time, at specified speeds. This enables organizations to re-establish the Positive Control Model which bends the “Vulnerability” curve and allows an infosec team with limited resources to reduce, what Jack Whitsitt calls, the adversaries’ “Offensive Advantage.”

On the endpoint side, Trusteer provides a type of Positive Control Model / whitelisting whereby highly targeted applications like browsers, Java, Adobe Flash, PDF, and Microsoft Office applications are automatically protected behaviorally. The Trusteer agent understands the memory state – file I/O relationship to the degree that it knows the difference between good I/O and malicious I/O behavior. Trusteer then blocks the malicious I/O before any damage can be done.

Thus human errors resulting from social engineering such as clicking on links to malicious web pages or opening documents containing malicious code are automatically blocked. This is all done with no policy configuration efforts on the part of the infosec team. The policies are updated by Trusteer periodically. There are no policies to configure. Furthermore, thousands of agents can be deployed in days. Finally, when implemented to deployed Windows and Mac endpoints, it will detect already compromised devices.

Trusteer, founded in 2006, has over 40 million agents deployed across the banking industry to protect online banking users. So their agent technology has been battle tested.

In closing then, only by implementing technical controls which establish a Positive Control Model to reduce human errors, can an organization bend the Vulnerability Curve sufficiently to reduce the adversaries’ Offensive Advantage to an acceptable level.

About Cymbel

Specialists in information security. Helping organizations secure their networks and mitigate the risks of modern threats.

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