In this article by David Steadman and Jeff Ingalls, the authors of Microsoft Identity Manager 2016 Handbook, we will look at certificate management in brief.
Microsoft Identity Management (MIM)—certificate management (CM)—is deemed the outcast in many discussions. We are here to tell you that this is not the case. We see many scenarios where CM makes the management of user-based certificates possible and improved. If you are currently using FIM certificate management or considering a new certificate management deployment with MIM, we think you will find that CM is a component to consider.
CM is not a requirement for using smart cards, but it adds a lot of functionality and security to the process of managing the complete life cycle of your smart cards and software-based certificates in a single forest or multiforest scenario.
In this article, we will look at the following topics:
What is CM?
Certificate management components
Certificate management agents
The certificate management permission model
(For more resources related to this topic, see here.)
What is certificate management?
Certificate management extends MIM functionality by adding management policy to a driven workflow that enables the complete life cycle of initial enrollment, duplication, and the revocation of user-based certificates. Some smart card features include offline unblocking, duplicating cards, and recovering a certificate from a lost card.
The concept of this policy is driven by a profile template within the CM application. Profile templates are stored in Active Directory, which means the application already has a built-in redundancy. CM is based on the idea that the product will proxy, or be the middle man, to make a request to and get one from CA. CM performs its functions with user agents that encrypt and decrypt its communications.
When discussing PKI (Public Key Infrastructure) and smart cards, you usually need to have some discussion about the level of assurance you would like for the identities secured by your PKI. For basic insight on PKI and assurance, take a look at http://bit.ly/CorePKI.
In typical scenarios, many PKI designers argue that you should use Hardware Security Module (HSM) to secure your PKI in order to get the assurance level to use smart cards. Our personal opinion is that HSMs are great if you need high assurance on your PKI, but smart cards increase your security even if your PKI has medium or low assurance. Using MIM CM with HSM will not be covered in this article, but if you take a look at http://bit.ly/CMandLunSA, you will find some guidelines on how to use MIM CM and HSM Luna SA.
The Financial Company has a low-assurance PKI with only one enterprise root CA issuing the certificates. The Financial Company does not use a HSM with their PKI or their MIM CM. If you are running a medium- or high-assurance PKI within your company, policies on how to issue smart cards may differ from the example. More details on PKI design can be found at http://bit.ly/PKIDesign.
Certificate management components
Before we talk about certificate management, we need to understand the underlying components and architecture:
As depicted before, we have several components at play. We will start from the left to the right. From a high level, we have the Enterprise CA. The Enterprise CA can be multiple CAs in the environment. Communication from the CM application server to the CA is over the DCOM/RPC channel. End user communication can be with the CM web page or with a new REST API via a modern client to enable the requesting of smart cards and the management of these cards.
From the CM perspective, the two mandatory components are the CM server and the CA modules. Looking at the logical architecture, we have the CA, and underneath this, we have the modules. The policy and exit module, once installed, control the communication and behavior of the CA based on your CM's needs.
Moving down the stack, we have Active Directory integration. AD integration is the nuts and bolts of the operation. Integration into AD can be very complex in some environments, so understanding this area and how CM interacts with it is very important. We will cover the permission model later in this article, but it is worth mentioning that most of the configuration is done and stored in AD along with the database. CM uses its own SQL database, and the default name is FIMCertificateManagement. The CM application uses its own dedicated IIS application pool account to gain access to the CM database in order to record transactions on behalf of users. By default, the application pool account is granted the clmApp role during the installation of the database, as shown in the following screenshot:
In CM, we have a concept called the profile template. The profile template is stored in the configuration partition of AD, and the security permissions on this container and its contents determine what a user is authorized to see. As depicted in the following screenshot, CM stores the data in the Public Key Services (1) and the Profile Templates container. CM then reads all the stored templates and the permissions to determine what a user has the right to do (2):
Profile templates are at the core of the CM logic. The three components comprising profile templates are certificate templates, profile details, and management policies. The first area of the profile template is certificate templates. Certificate templates define the extensions and data point that can be included in the certificate being requested.
The next item is profile details, which determines the type of request (either a smart card or a software user-based certificate), where we will generate the certificates (either on the server or on the client side of the operations), and which certificate templates will be included in the request.
The final area of a profile template is known as management policies. Management policies are the workflow engine of the process and contain the manager, the subscriber functions, and any data collection items. The e-mail function is initiated here and commonly referred to as the One Time Password (OTP) activity. Note the word "One". A trigger will only happen once here; therefore, multiple alerts using e-mail would have to be engineered through alternate means, such as using the MIM service and expiration activities.
The permission model is a bit complex, but you'll soon see the flexibility it provides. Keep in mind that Service Connection Point (SCP) also has permissions applied to it to determine who can log in to the portal and what rights the user has within the portal.
SCP is created upon installation during the wizard configuration. You will want to be aware of the SCP location in case you run into configuration issues with administrators not being able to perform particular functions. The SCP location is in the System container, within Microsoft, and within Certificate Lifecycle Manager, as shown here:
Typical location CN=Certificate Lifecycle Manager,CN=Microsoft,CN=System,DC=THEFINANCIALCOMPANY,DC=NET
Certificate management agents
We covered several key components of the profile templates and where some of the permission model is stored. We now need to understand how the separation of duties is defined within the agent role. The permission model provides granular control, which promotes the separation of duties. CM uses six agent accounts, and they can be named to fit your organization's requiremensts. We will walk through the initial setup again later in this article so that you can use our setup or alter it based on your need. The Financial Company only requires the typical setup. We precreated the following accounts for TFC, but the wizard will create them for you if you do not use them. During the installation and configuration of CM, we will use the following accounts:
Besides the separation of duty, CM offers enrollment by proxy. Proxy enrollment of a request refers to providing a middle man to provide the end user with a fluid workflow during enrollment. Most of this proxy is accomplished via the agent accounts in one way or another. The first account is MIM CM Agent (MIMCMAgent), which is used by the CM server to encrypt data from the smart card admin PINs to the data collection stored in the database. So, the agent account has an important role to protect data and communication to and from the certificate authorities. The last user agent role CMAgent has is the capability to revoke certificates. The agent certificate thumbprint is very important, and you need to make sure the correct value is updated in the three areas: CM, web.config, and the certificate policy module under the Signing Certificates tab on the CA. We have identified these areas in the following.
For web.config:
<add key="Clm.SigningCertificate.Hash" value
<add key="Clm.Encryption.Certificate.Hash" value
<add key="Clm.SmartCard.ExchangeCertificate.Hash" value
The Signing Certificates tab is as shown in the following screenshot:
Now, when you run through the configuration wizard, these items are already updated, but it is good to know which locations need to be updated if you need to troubleshoot agent issues or even update/renew this certificate.
The second account we want to look at is Key Recovery Agent (MIMCMKRAgent); this agent account is needed for CM to recover any archived private keys certificates.
Now, let's look at Enrollment Agent (MIMCMEnrollAgent); the main purpose of this agent account is to provide the enrollment of smart cards. Enrollment Agent, as we call it, is responsible for signing all smart card requests before they are submitted to the CA. Typical permission for this account on the CA is read and request.
Authorization Agent (MIMCMAuthAgent)—or as some folks call this, the authentication agent—is responsible for determining access rights for all objects from a DACL perspective. When you log in to the CM site, it is the authorization account's job to determine what you have the right to do based on all the core components that ACL has applied. We will go over all the agents accounts and rights needed later in this article during our setup.
CA Manager Agent (MIMCMManagerAgent) is used to perform core CA functions. More importantly, its job is to issue Certificate Revocation Lists (CRLs). This happens when a smart card or certificate is retired or revoked. It is up to this account to make sure the CRL is updated with this critical information.
We saved the best for last: Web Pool Agent (MIMCMWebAgent). This agent is used to run the CM web application. The agent is the account that contacts the SQL server to record all user and admin transactions.
The following is a good depiction of all the accounts together and the high-level functions:
The certificate management permission model
In CM, we think this part is the most complex because with the implementation, you can be as granular as possible. For this reason, this area is the most difficult to understand. We will uncover the permission model so that we can begin to understand how the permission model works within CM.
When looking at CM, you need to formulate the type of management model you will be deploying. What we mean by this is will you have a centralized or delegated model? This plays a key part in deployment planning for CM and the permission you will need to apply.
In the centralized model, a specific set of managers are assigned all the rights for the management policy. This includes permissions on the users. Most environments use this method as it is less complex for environments. Now, within this model, we have manager-initiated permission, and this is where CM permissions are assigned to groups containing the subscribers. Subscribers are the actual users doing the enrollment or participating in the workflow. This is the model that The Financial Company will use in its configuration.
The delegated model is created by updating two flags in web.config called clm.RequestSecurity.Flags and clm.RequestSecurity.Groups.
These two flags work hand in hand as if you have UseGroups, then it will evaluate all the groups within the forests to include universal/global security. Now, if you use UseGroups and define clm.RequestSecurity.Groups, then it will only look for these specific groups and evaluate via the Authorization Agent . The user will tell the Authorization Agent to only read the permission on the user and ignore any group membership permissions:
When we continue to look at the permission, there are five locations that permissions can be applied in. In the preceding figure is an outline of these locations, but we will go in more depth in the subsections in a bit. The basis of the figure is to understand the location and what permission can be applied. The following are the areas and the permissions that can be set:
Service Connection Point: Extended Permissions
Users or Groups: Extended Permissions
Profile Template Objects:
Container: Read or Write
Template Object: Read/Write or Enroll
Certificate Template: Read or Enroll
CM Management Policy within the Web application: We have multiple options based on the need, such as Initiate Request
Now, let's begin to discuss the core areas to understand what they can do. So, The Financial Company can design the enrollment option they want. In the example, we will use the main scenario we encounter, such as the helpdesk, manager, and user-(subscriber) based scenarios. For example, certain functions are delegated to the helpdesk to allow them to assist the user base without giving them full control over the environment (delegated model). Remember this as we look at the five core permission areas.
Creating service accounts
So far, in our MIM deployment, we have created quite a few service accounts. MIM CM, however, requires that we create a few more. During the configuration wizard, we will get the option of having the wizard create them for us, but we always recommend creating them manually in FIM/MIM CM deployments.
One reason is that a few of these need to be assigned some certificates. If we use an HSM, we have to create it manually in order to make sure the certificates are indeed using the HSM.
The wizard will ask for six different service accounts (agents), but we actually need seven.
In The Financial Company, we created the following seven accounts to be used by FIM/MIM CM:
MIMCMAgent
MIMCMAuthAgent
MIMCMCAManagerAgent
MIMCMEnrollAgent
MIMCMKRAgent
MIMCMWebAgent
MIMCMService
The last one, MIMCMService, will not be used during the configuration wizard, but it will be used to run the MIM CM Update service.
We also created the following security groups to help us out in the scenarios we will go over:
MIMCM-Helpdesk: This is the next step in OTP for subscribers
MIMCM-Managers: These are the managers of the CM environment
MIMCM-Subscribers: This is group of users that will enroll
Service Connection Point
Service Connection Point (SCP)is located under the Systems folder within Active Directory. This location, as discussed in the earlier parts of the article, defines who functions as the user as it relates to logging in to the web application. As an example, if we just wanted every user to only log in, we would give them read rights. Again, authenticated users, have this by default, but if you only wanted a subset of users to access, you should remove authenticated users and add your group.
When you run the configuration wizard, SCP is decided, but the default is the one shown in the following screenshot:
If a user is assigned to any of the MIM CM permissions available on SCP, the administrative view of the MIM CM portal will be shown.
The MIM CM permissions are defined in a Microsoft TechNet article at http://bit.ly/MIMCMPermission. For your convenience, we have copied parts of the information here:
MIM CM Audit: This generates and displays MIM CM policy templates, defines management policies within a profile template, and generates MIM CM reports.
MIM CM Enrollment Agent: This performs certificate requests for the user or group on behalf of another user. The issued certificate's subject contains the target user's name and not the requester's name.
MIM CM Request Enroll: This initiates, executes, or completes an enrollment request.
MIM CM Request Recover: This initiates encryption key recovery from the CA database.
MIM CM Request Renew: This initiates, executes, or completes an enrollment request. The renewal request replaces a user's certificate that is near its expiration date with a new certificate that has a new validity period.
MIM CM Request Revoke: This revokes a certificate before the expiration of the certificate's validity period. This may be necessary, for example, if a user's computer or smart card is stolen.
MIM CM Request Unblock Smart Card: This resets a smart card's user Personal Identification Number (PIN) so that he/she can access the key material on a smart card.
The Active Directory extended permissions
So, even if you have the SCP defined, we still need to set up the permissions on the user or group of users that we want to manage. As in our helpdesk example, if we want to perform certain functions, the most common one is offline unblock. This would require the MIMCM-HelpDesk group. We will create this group later in this article. It would contain all help desk users then on SCP; we would give them CM Request Unblock Smart Card and CM Enrollment Agent. Then, you need to assign the permission to the extended permission on MIMCM-Subscribers, which contains all the users we plan to manage with the helpdesk and offline unblock:
So, as you can see, we are getting into redundant permissions, but depending on the location, it means what the user can do. So, planning of the model is very important. Also, it is important to document what you have as with some slight tweak, things can and will break.
The certificate templates permission
In order for any of this to be possible, we still need to give permission to the manager of the user to enroll or read the certificate template, as this will be added to the profile template. For anyone to manage this certificate, everyone will need read and enroll permissions. This is pretty basic, but that is it, as shown in the following screenshot:
The profile template permission
The profile template determines what a user can read within the template. To get to the profile template, we need to use Active Directory sites and services to manage profile templates. We need to activate the services node as this is not shown by default, and to do this, we will click on View | Show Services Node:
As an example if you want a user to enroll in the cert, he/she would need CM Enroll on the profile template, as shown in the following screenshot:
Now, this is for users, but let's say you want to delegate the creation of profile templates. For this, all you need to do is give the MIMCM-Managers delegate the right to create all child items on the profile template container, as follows:
The management policy permission
For the management policy, we will break it down into two sections: a software-based policy and a smart card management policy. As we have different capabilities within CM based on the type, by default, CM comes with two sample policies (take a look at the following screenshot), which we use for duplication to create a new one. When configuring, it is good to know that you cannot combine software and smart card-based certificates in a policy:
The software management policy
The software-based certificate policy has the following policies available through the CM life cycle:
The Duplicate Policy panel creates a duplicate of all the certificates in the current profile. Now, if the first profile is created for the user, all the other profiles created afterwards will be considered duplicate, and the first generated policy will be primary.
The Enroll Policy panel defines the initial enrollment steps for certificates such as initiate enroll request and data collection during enroll initiation.
The Online Update Policy panel is part of the automatic policy function when key items in the policy change. This includes certificates about to expire, when a certificate is added to the existing profile template or even removed.
The Recover Policy panel allows for the recovery of the profile in the event that the user was deleted. This includes the cases where certs are deleted by accident. One thing to point out is if the certificate was a signing cert, the recovery policy would issue a new replacement cert. However, if the cert was used for encryption, you can recover the original using this policy.
The Recover On Behalf Policy panel allows managers or helpdesk operations to be recovered on behalf the user in the event that they need any of the certificates.
The Renew Policy panel is the workflow that defines the renew setting, such as revocation and who can initiate a request.
The Suspend and Reinstate Policy panel enables a temporary revocation of the profile and puts a "certificate hold" status. More information about the CRL status can be found at http://bit.ly/MIMCMCertificateStatus.
The Revoke Policy panel maintains the revocation policy and setting around being able to set the revocation reason and delay. Also, it allows the system to push a delta CRL. You also can define the initiators for this policy workflow.
The smart card management policy
The smart card policy has some similarities to the software-based policy, but it also has a few new workflows to manage the full life cycle of the smart card:
The Profile Details panel is by far the most commonly used part in this section of the policy as it defines all the smart card certificates that will be loaded in the policy along with the type of provider. One key item is creating and destroying virtual smart cards. One final key part is diversifying the admin key. This is best practice as this secures the admin PIN using diversification. So, before we continue, we want to go over this setting as we think it is an important topic.
Diversifying the admin key is important because each card or batch of cards comes with a default admin key. Smart cards may have several PINs, an admin PIN, a PINunlock key (PUK), and a user PIN. This admin key, as CM refers to it, is also known as the administrator PIN. This PIN differs from the user's PIN. When personalizing the smart card, you configure the admin key, the PUK, and the user's PIN. The admin key and the PUK are used to reset the virtual smart card's PIN. However, you cannot configure both. You must use the PUK to unlock the PIN if you assign one during the virtual smart card's creation.
It is important to note that you must use the PUK to reset the PIN if you provide both a PUK and an admin key.
During the configuration of the profile template, you will be asked to enter this key as follows:
The admin key is typically used by smart card management solutions that enable a challenge response approach to PIN unlocking. The card provides a set of random data that the user reads (after the verification of identity) to the deployment admin. The admin then encrypts the data with the admin key (obtained as mentioned before) and gives the encrypted data back to the user. If the encrypted data matches that produced by the card during verification, the card will allow PIN resetting. As the admin key is never in the hands of anyone other than the deployment administrator, it cannot be intercepted or recorded by any other party (including the employee) and thus has significant security benefits beyond those in using a PUK—an important consideration during the personalization process.
When enabled, the admin key is set to a card-unique value when the card is assigned to the user. The option to diversify admin keys with the default initialization provider allows MIM CM to use an algorithm to uniquely generate a new key on the card. The key is encrypted and securely transmitted to the client. It is not stored in the database or anywhere else. MIM CM recalculates the key as needed to manage the card:
The CM profile template contains a thumbprint for the certificate to be used in admin key diversification. CM looks in the personal store of the CM agent service account for the private key of the certificate in the profile template. Once located, the private key is used to calculate the admin key for the smart card. The admin key allows CM to manage the smart card (issuing, revoking, retiring, renewing, and so on). Loss of the private key prevents the management of cards diversified using this certificate.
More detail on the control can be found at http://bit.ly/MIMCMDiversifyAdminKey.
Continuing on, the Disable Policy panel defines the termination of the smart card before expiration, you can define the reason if you choose. Once disabled, it cannot be reused in the environment.
The Duplicate Policy panel, similarly to the software-based one, produces a duplicate of all the certificates that will be on the smart card.
The Enroll Policy panel, similarly to the software policy, defines who can initiate the workflow and printing options.
The Online Update Policy panel, similarly to the software-based cert, allows for the updating of certificates if the profile template is updated. The update is triggered when a renewal happens or, similarly to the software policy, a cert is added or removed.
The Offline Unblock Policy panel is the configuration of a process to allow offline unblocking. This is used when a user is not connected to the network. This process only supports Microsoft-based smart cards with challenge questions and answers via, in most cases, the user calling the helpdesk.
The Recovery On Behalf Policy panel allows the recovery of certificates for the management or the business to recover if the cert is needed to decrypt information from a user whose contract was terminated or who left the company.
The Replace Policy panel is utilized by being able to replace a user's certificate in the event of a them losing their card. If the card they had had a signing cert, then a new signing cert would be issued on this new card. Like with software certs, if the certificate type is encryption, then it would need to be restored on the replace policy.
The Renew Policy panel will be used when the profile/certificate is in the renewal period and defines revocation details and options and initiates permission.
The Suspend and Reinstate Policy panel is the same as the software-based policy for putting the certificate on hold.
The Retire Policy panel is similar to the disable policy, but a key difference is that this policy allows the card to be reused within the environment.
The Unblock Policy panel defines the users that can perform an actual unblocking of a smart card.
More in-depth detail of these policies can be found at http://bit.ly/MIMCMProfiletempates.
Summary
In this article, we uncovered the basics of certificate management and the management components that are required to successfully deploy a CM solution. Then, we discussed and outlined, agent accounts and the roles they play. Finally, we looked into the management permission model from the policy template to the permissions and the workflow.
Resources for Article:
Further resources on this subject:
Managing Network Devices [article]
Logging and Monitoring [article]
Creating Horizon Desktop Pools [article]
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