Access Controls – CompTIA Security+ SY0-701 – 4.6

There are many different ways to provide authorization, rights, and permissions. In this video, you’ll learn about least privilege, access control types, time-of-day restrictions, and more.


Once someone authenticates to a network, we still need to provide them with access to the resources they need to be able to perform their job function. We refer to this as access control, and it’s a process of enforcing the policies that would allow or disallow someone access to data.

This access control can be associated with an individual or a group of individuals. There’s usually a process that defines the policy of what someone may need access to, and then the IT team needs to take that policy and change it into the process required by the operating system to allow or disallow rights to data.

There are very broad access control models, and we’ll look at those models in this video. There are slight differences between these different types of access controls, and different organizations can choose the access control that’s best for them.

We’ll first start with a security best practice that can be applied across any of these access controls, and that best practice is least privilege. Least privilege means that we will assign rights and permissions to a user that gives them exactly what they need to perform their job. We don’t give them additional rights and permissions, and we certainly wouldn’t provide them with administrator access.

This means, by default, every user will have limited privileges to the operating system. If a user does happen to run malicious software, that software would only have the rights and permissions associated with that user and would hopefully limit the scope of any damage.

If you’re working in a highly secure area, you may be working with an access control called a mandatory access control. Mandatory access control assigns a label to each resource that someone may need access to. So a particular file or folder may be tagged as confidential, secret, top secret, or a number of other types of mandatory access control labels.

One important aspect of a mandatory access control is that the administrator of the system is the one that defines what type of rights and permissions a user might have. So a user in the shipping and receiving department may have access to confidential data. But someone who’s higher up in the management chain might have access to top secret data.

One very common type of access control is a discretionary access control. With a discretionary control model, the user that creates the data has the control on who can access the data and how they can access that information. For example, if you create a spreadsheet, you get to decide who else has access to that spreadsheet. And you can also set different permissions to the users who may have access, where some people can modify the spreadsheet and others might only be read-only.

This allows the owner of the data to have complete control on who can access that information. This access control gives the owner of the data great deal of flexibility when determining who has access to that data. Unfortunately, this also means that this level of access is also less secure because you’re relying on each individual user to set the appropriate security controls for every piece of data they create.

A more centralized control model would be a role-based access control. This access control is based on your job function. So if you are a manager, you have a certain type of rights and permissions to data. If you’re a director, you have a different set of rights and permissions. And if you’re a team lead or project manager, there are different sets of permissions for those roles as well.

This starts with the administrator of the system creating a number of different groups. There might be a manager group, a director group, a team lead group, and a project manager group. They would then assign rights and permissions to the group itself, knowing that managers have a certain type of rights and permissions, director have a completely different set, and so on.

Once this group is created by the administrator and rights are assigned to the group, the administrator will add users to that group. Each user added to the group receives the rights and permissions associated with that group. So we don’t have to assign specific permissions directly to a user. We can simply add that user to the group, and they receive all of those permissions implicitly.

In Windows, this is referred to as groups, and you can associate a role-based access control to each group. For example, you might have a group for shipping and receiving, and you can associate rights and permissions to the shipping software for anyone who might be in that group. You might also have a group for managers of shipping and receiving, and managers might have additional access that allows them to view the shipping logs.

Some access control methods have a list of rules, and those rules are associated with rights and permissions. We refer to this as a rule-based access control because there are a number of system-enforced rules that are created by the system administrator. This means the user does not control any of the rights and permissions or create any of the rules. The administrator is responsible for configuring and assigning all of those permissions.

With a rule-based access control, we would first create a rule, and then we would associate that rule with a specific object. Each user that accesses that object is then checked in the rule base to see if any of those rules might apply to that individual. For example, there might be a user that needs to access data that’s located in a lab. But there is a rule associated with that data that says you can only gain access if the time is between 9:00 AM and 5:00 PM. And if somebody tries to access the data that’s outside of that schedule, that rule would not allow access.

Or the rule might be that a form on a web page can only be filled out by someone using the Chrome browser. This rule-based access control allows an administrator to set any type of criteria and associate that criteria with a specific object.

A more modern style of access control is the attribute-based access control. With an attribute-based access control, there are many different criteria that you can use to determine whether someone would have access to data or not. This allows administrators to create very complex rule sets that determine whether certain types of data are accessible or not. You can think of this as a next generation of an authorization model.

So a type of access control that takes into account a number of different criteria may be evaluating the IP address of the person making the request, the time of day, the desired action, whether they’re writing or reading information, and what relationship they might have to the data. The administrator can combine many different criteria together to determine exactly what type of control someone might have over any object.

One type of restriction that can be applied across many of these different control models is a time of day restriction. This means an administrator can allow or disallow access to a certain type of data or resource object based on what time of the day it happens to be. This may not be the only access control method, but it does provide the administrator with options when configuring access to data.

Of course, when you’re working with the time of day or the day of the week, this can become very complicated if you are a worldwide organization. So an administrator might include not just the time of day restriction but what time zone is native for that particular user. So a good example of some time of day restrictions might be that a training room network is inaccessible between the hours of midnight and 6:00 AM. Or it may be that conference room access is limited after 8:00 PM. And if you want to access certain types of data, the R&D databases are only available between the hours of 8:00 AM and 6:00 PM.