Home > Articles > Security > General Security and Privacy

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

Identifying Control Nodes

Now that we have a new way of approaching the problem using closed-loop process control, all we have to do is identify those parts of our network that can assist with the basic control modes associated with proportional, integral, and derivative controls.

Map Technology to Control Nodes

A control node is a place where we can enforce a condition or extract data for the purposes of managing the process. In our networks, we have multiple devices that we can easily consider control nodes, including the following:

  • Switches
  • Routers
  • VPN gateways
  • DHCP servers

These are great examples of control nodes because they all have the capability to decide what happens to the traffic that passes through them. In addition, they all can report data that enables us to make other decisions in support of either derivative or integral control functions.

From a basic security perspective, we also have the following:

  • Firewalls
  • IDSs (intrusion detection systems)
  • IPSs (intrusion prevention systems)
  • AV systems (antivirus systems)

Map Control Nodes to Control Modes

When we consider their roles in our PID-based solution, we can see that most of these systems, with a few exceptions, fall under the category of derivative controls. Their purpose is to help us understand just how fast things are changing and to give us notice that we might have to deal with an overshoot of our expected status quo. I say "overshoot" because it's not often that our systems notify us that nothing is happening.

As mentioned previously, we can use some log information to provide an integration function. Three failed login attempts and the endpoint is locked out for a period of ten minutes is a good example of this function.

The exceptions I was referring to earlier are firewalls and VPN concentrators. Firewalls and VPN concentrators can also function as proportional controls if their operation is tied to some action such as limiting traffic loads rather than the simple bimodal yes or no. However, some people are not comfortable with the idea that an automated system can change the configuration of the network. Failures have occurred, and money has been lost, so now there is usually a human in the loop.

In Table 3-1, you can see how the different types of technology map to the four control modes. Devices can be classified as proportional, derivative, or integral. Some devices are simple bimodal on or off and are called bang-bang controls.

Table 3-1. Devices Mapped to Control Modes

Device

Function

Proportional

Integral

Derivative

Bang-Bang

Firewall

Perimeter control

Not alone

No

No

Yes

HIDS

Intrusion trigger

No

No

Yes

Yes

NIDS

IRP trigger

No

No

Yes

Yes

HIPS

Attack prevention

No

No

No

Yes

NIPS

Network protection

No

No

No

Yes

SAV

Server AV

No

No

No

Yes

EAV

Endpoint AV

No

No

No

Yes

Router

Traffic control

No

No

No

Yes

Switch

Traffic control

No

No

No

Yes

VPN

Privacy enforcement

Not alone

No

No

Yes

DHCP

Network provisioning

No

No

No

Yes

Probes

Vulnerability assessment

No

Yes

No

No

Logs

Due diligence

No

Yes

Yes

Yes

Alerts

IRP trigger

No

No

Yes

Yes

Correlation (SIM)

Policy management

No

Yes

Yes

No

Now, just to confuse things a little, all these systems also function as bang-bang controls, because they make binary decisions about what to do with traffic. Either it passes traffic or it doesn't. I think it's this dual-mode operation has masked their possible contribution as control systems.

Quantify Time Constants

A time constant is just the amount of time it takes to complete any specific part of the process. If it takes one minute to fill the toilet bowl prior to a reflush, the time constant for that process is one minute. If you try to recycle the process before the time constant completes, you wind up with less than satisfactory results. To have an effective process control system, you must understand these time constants; otherwise, you risk creating a system that oscillates wildly around the set-point.

The hard part is identifying them in your process and accurately measuring them. This is part of what the metrics people are trying to do. The problem is that each enterprise has a different set of requirements and dependencies, and therefore the same process in a different environment has different time constants associated with it.

Let's look at the incident response cycle again. Every enterprise that has a decent security program has an incident response plan. It's triggered when something evil happens and an alert is sent "somewhere." Maybe the IDS has seen a suspicious packet stream and has sent out an alert, or perhaps the help desk has too many trouble tickets complaining of slow systems. In many cases, this alert is sent to the security group. Someone with a pager gets the alert and either runs to a computer or, if that person is off-site, makes a phone call. That call can be to someone close to the system or it can be to the data center. After the call has been made, the process of evaluating the event kicks into gear, and the decision process takes over:

  • Is it a false positive?
  • Is it a truly evil event?
  • Is it internal or external?
  • Are we hemorrhaging data?
  • Can we recover?
  • Do we need to call law enforcement?
  • How much time has elapsed since the initial alert?

For most organizations, this time constant will probably be on the order of minutes.

By deconstructing the processes, you can discover how long each individual part of it takes, and thus identify where you should put your effort to improve it. Each breakpoint in the process is an opportunity to gather some information about the state of the process.

We can move from the alerting entity to the notification channel, through the analysis process, and into the resolution process, tracking the time it takes for each. For example, we examine our analysis portion of our hypothetical process and discover that the notification process takes more than 15 minutes. Clearly, 15 minutes is not a reasonable time to be notified that a critical condition exists on your network.

Another benefit of this effort is to identify exactly where the various control nodes in your network are, be they technological or human based. You now have a list that you can use or pass on to someone else. What you've done is move from a talent-based response to a role-based response that doesn't pigeonhole you as a resource. You'll also discover that the human-based process components are the ones with the long time constants and, by the way, the ones with the lowest level of repeatability and reliability.

Control Paths and the Business Processes

You might be wondering what exactly a control path is. A control path is the path that the control and feedback signals take to change the set-point of the system. I believe that you need to map your control paths to the business processes to understand where the cracks in the security process are. Understanding how control signals are generated and understanding where they go, and possibly don't go, can prove critical to your success. This can also help you understand where a little bit of automation can make your life a lot easier (and identify some important metrics).

Let's start by looking at some of the information that passes through a control path. We'll call this our control signal. Perhaps that will help us understand how the business process affects our control process. Because we're talking about security, let's define a control signal as anything that is security relevant, such as the following:

  • Failed login attempts
  • Firewall rule violations
  • IDS alerts
  • New user requests
  • User termination
  • New software requests
  • New protocol requests
  • Software decommissioning
  • Network access requests

Next, we have to ask ourselves how much of this information is made available to us by our control nodes as they were defined in the previous section, and how much is made available to us by the business process. As you can see, things such as firewall rule violations and IDS alerts are more like spam, because they're "made available" to us all the time in large numbers. However, the rest of them are made available to us through a business process that may or may not include the security group in the notification path.

The other sad part of this story is that all these processes are open loop—that is, there is no notification that they were completed, denied, or simply disregarded. How do you manage network access requests? Does a verification process occur prior to the decision to allow access? In most cases, the answer is yes, but only for that particular moment. After access has been granted, there is little follow-up to ensure that the system remains compliant with policy, so our control process breaks at the point where we hand the user his or her system.

Another good example starts with a question: Where do login errors go, and how are they processed? A large number of failed logins can indicate that someone is trying to break into your network. If that's the case, the behavior of the network should change in a way that attempts to eliminate those login attempts. In many cases, low-frequency failures are not noticed because they don't trigger the "three failed attempts per hour" rule. This kind of low and slow attack can easily be automated, but is difficult to detect. An interesting metric that you can use as a control signal is the number of failed login attempts compared to the number of successful attempts per user over a longer period of time (for example, a day). You can then compare that number to the preceding day and look for trends.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020