Check if all DC are well registered.

S-DCRegistration

The purpose is to ensure that DC are well registered.

To be registered as a domain controller, a computer must be a member of the domain controller group, but also has some specific settings.
The settings are a change of the userAccountControl attribute and a couple of objects in the configuration partition.
This rule is triggered when an inconsistency has been detected between the expected values and the real values.

The user account control value for Read/Write DC is:
SERVER_TRUST_ACCOUNT (0x00002000) | TRUSTED_FOR_DELEGATION (0x00080000) = 0x00082000
The user account control value for Read Only DC is:
PARTIAL_SECRETS_ACCOUNT (0x04000000) | TRUSTED_TO_AUTHENTICATE_FOR_DELEGATION (0x01000000) | WORKSTATION_TRUST_ACCOUNT (0x00001000) = 0x05001000

This rule result is either the result of a manual or software based misconfiguration. It can also be the sign of a compromise.
Depending on the anonamly reported, you have to perform the following actions:
- for InvalidUserAccount:
you have to check that the userAccountControl attribute of the AD object is either 0x00082000 for RW DC or 0x05001000 for RODC
- for NoConfiguration:
the DC registration in the Configuration partition is mising. The DC should not be active and need to be demoted.
- for NoNTDS:
the NTDS part of the DC Configuration is missing. Most probably the replication is not working. The DC should be demoted.

10 points if present

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-adts/9164e4e8-f892-4ca2-8067-059f6f9387a4
https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-adts/8ebf2419-1169-4413-88e2-12a5ad499cf5
[MITRE]T1207 Rogue Domain Controller
[FR]ANSSI - Domain controllers in inconsistent state (vuln1_dc_inconsistent_uac)1

The detail can be found in Domain controllers

Check for the ROCA vulnerability in certificates

A-CertROCA

The purpose is to ensure that there is no private key that can be recovered from a certificate

"ROCA" is an acronym for "Return of Coppersmith's attack" which enables an attacker to retrieve the private key from a public key.
It is due by a library named RSALib, provided by Infineon Technologies which is incorporated into many smart cards, Trusted Platform Module (TPM), and Hardware Security Modules (HSM) implementations, including YubiKey 4 tokens and used to generate public RSA keys.
This library was generating data in a limited number space, which decreased the number of values that an attacker has to guess.

If the certificates listed below are still valid, you have to revoke and re-issue them. If other certificates depends on them, they should be revoked and replaced too.
If the certificates have been expired, they should be removed.

15 points if present

https://crocs.fi.muni.cz/public/papers/rsa_ccs17
https://github.com/crocs-muni/roca
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV190026
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV170012
https://keychest.net/roca
[FR]ANSSI - Weak or vulnerable certificates (vuln1_certificates_vuln)1
[MITRE]T1600.001 Weaken Encryption: Reduce Key Space

The detail can be found in Certificates

Check if LDAPS is used with weak SSL protocol.

A-DCLdapsProtocol

The purpose is to ensure that all DC don't use weak SSL protocols when acting as server.

SSL version 2 and SSL version 3 are considered weak and it is strongly advised to disable them.
The SSL protocols in Windows is provided by the Schannel component.
The Schannel component needs to be tuned in order to not propose these weak protocols. Many guidelines to handle this problem issued by Microsoft do not talk about Schannel but rather IIS. These guidlines are quoted in the documentation section below.

PingCastle is able to check the SSL version if LDAPS is exposed. LDAPS is automatically exposed once a certificate is available for the DC and the service restarted.
Please note that PingCastle is using the native .Net SSL stack to perform this test. .Net begins to ignore these weak protocols starting the version 4.7 of the framework and as a consequence, PingCasle may miss some weak protocol detection.

To test these protocol, you can use openssl with the following commands:
openssl s_client -connect dc.domain.local:636 -ssl2
openssl s_client -connect dc.domain.local:636 -ssl3

Apply Windows updates and registry tweaks described in the documentation section to disable the weak SSL protocols.

10 points if present

https://social.technet.microsoft.com/wiki/contents/articles/2249.windows-server-20082008r2-how-to-disable-sslv2-on-domain-controller-dsforum2wiki.aspx
https://support.microsoft.com/en-us/help/187498/how-to-disable-pct-1-0-ssl-2-0-ssl-3-0-or-tls-1-0-in-internet-informat
https://adsecurity.org/?p=376
[MITRE]T1600.001 Weaken Encryption: Reduce Key Space

The detail can be found in Domain controllers

Check for Intermediate Certificates using unsafe hashing algorithm (SHA1)

A-SHA1IntermediateCert

The purpose is to ensure that there is no use of the SHA1 hashing algorithm in Intermediate Certificate

The SHA1 hashing algorithm is not considered as safe. There are design flaws inherent to the algorithm that allow an attacker to generate a hash collision in less than a brute-force time

To solve the matter, the certificate should be removed from the GPO and if needed, certificates depending on it should be reissued.

1 points if present

https://tools.ietf.org/html/rfc6194
[MITRE]T1600.001 Weaken Encryption: Reduce Key Space
[US]STIG V-14820 - PKI certificates (server and clients) must be issued by the DoD PKI or an approved External Certificate Authority (ECA).
[FR]ANSSI - Weak or vulnerable certificates (vuln3_certificates_vuln)3

The detail can be found in Certificates

Check for Certificates using a relatively weak signing algorithm (RSA between 1024 bits and 2048)

A-WeakRSARootCert2

The purpose is to ensure that there is no use of a certificate using a relatively weak RSA key

A RSA key certificate with a modulus under 1024 bits is considered as not safe. This is checked by the rule A-WeakRSARootCert.
This rule checks for certificates having a key under 2048 bits which is considered as having a lower level of security and under 3072 bits for certificates valid after 2030.

To solve the matter, the certificate should be removed from the GPO and if needed, certificates depending on it should be reissued.

Please note that this rule is the companion of the rule A-WeakRSARootCert which checks for unsecured certificates (key lower than 1024 bits).

1 points if present

https://www.iad.gov/iad/library/ia-guidance/ia-solutions-for-classified/algorithm-guidance/commercial-national-security-algorithm-suite-factsheet.cfm
https://www.ssi.gouv.fr/guide/cryptographie-les-regles-du-rgs/
[FR]ANSSI - Weak or vulnerable certificates (vuln3_certificates_vuln)3
[MITRE]T1600.001 Weaken Encryption: Reduce Key Space
[US]STIG V-14820 - PKI certificates (server and clients) must be issued by the DoD PKI or an approved External Certificate Authority (ECA).

The detail can be found in Certificates

Check for Root Certificates using unsafe hashing algorithm (SHA1)

A-SHA1RootCert

The purpose is to ensure that there is no use of the SHA1 hashing algorithm in Root Certificate

The SHA1 hashing algorithm is not considered as safe. There are design flaws inherent to the algorithm that allow an attacker to generate a hash collision in less than a brute-force time

To solve the matter, the certificate should be removed from the GPO and if needed, certificates depending on it should be reissued.

Informative rule (0 point)

https://tools.ietf.org/html/rfc6194
[MITRE]T1600.001 Weaken Encryption: Reduce Key Space
[FR]ANSSI - Weak or vulnerable certificates (vuln3_certificates_vuln)3
[US]STIG V-14820 - PKI certificates (server and clients) must be issued by the DoD PKI or an approved External Certificate Authority (ECA).

The detail can be found in Certificates

Check for Accounts using Smart Card with unchanged password for a long time

A-SmartCardRequired

The purpose is to make sure the requirement of Smart Cards doesn't degrade password rotation

Using Smart Card to protected sensitive account is a good thing. Nevertheless, when the "Smart Card required" flag is set, the password of the account is not changed anymore by default. Internally the hash of this password is used to sign the user's kerberos tickets, making this account vulnerable to Silver ticket attacks. The rule is triggered 90 days after the last change of the attribute unicodePwd. This value is collected using the replication metadata of the attribute 589914

There are 3 solutions to fix this issue, the most obvious being to change the user password on a regular basis. The fastest way is to check if the domain has the attribute msDS-ExpirePasswordsOnSmartCardOnlyAccounts, which is available for Windows 2016 and later versions and handle periodically hash change. Another possibility instead of changing the password is to disable the flag "this account requires a smart card" then re-enable it which will trigger internally a password hash change.

30 points if present

https://blogs.technet.microsoft.com/positivesecurity/2017/05/17/smartcard-and-pass-the-hash/
[MITRE]T1110.002 Brute Force: Password Cracking
[US]STIG V-72821 - All accounts, privileged and unprivileged, that require smart cards must have the underlying NT hash rotated at least every 60 days.
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R38 [paragraph.3.6.2.2]

The detail can be found in Smart Card and Password

Check for GPO which enable reversible passwords

A-ReversiblePwd

The purpose is to verify if a GPO alters the password policy of the domain to enable reversible passwords

The policy "Store passwords using reversible encryption" is enabled. In this case, it means that the password is actually stored in clear text in the supplementalCredential attribute of the account and that it can be retrieved using DCSync attack.

In order to remove the anonymous access, we advise to identify the GPO indicated by the program and change the setting "Store passwords using reversible encryption"

10 points if present

https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/store-passwords-using-reversible-encryption
[MITRE]T1110.002 Brute Force: Password Cracking
[FR]ANSSI - Accounts with passwords stored using reversible encryption (vuln3_reversible_password)3

The detail can be found in Security settings

Check for GPO enabling the unsafe algorithm LM hash

A-LMHashAuthorized

The authentication protocol NTLM v1 can use the LM password hash algorithm which is weak if enabled by a GPO.

LM hash, or LAN Manager hash is a hash algorithm developed by Microsoft since Windows 3.1. Due to flaw design, hashes retrieved from the network can be reverted to the clear text password in a matter of seconds.

A GPO explicitly disabled the default security policy LmCompatibilityLevel or NoLMHash. Using the information provided, identify the setting modified in the GPO and fix it.
All security settings should be modified in the Domain GPO Editor and are located in Computer Configuration / Policies / Windows Settings / Security Settings / Local Policies / Security Options
For NoLMHash the setting is located in: Network security: Do not store LAN Manager hash value on next password change
For LmCompatibilityLevel the setting is located in: Network security: LAN Manager authentication level

5 points if present

[MITRE]T1110.002 Brute Force: Password Cracking
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R37 [paragraph.3.6.2.1]
[US]STIG V-3379 - The system is configured to store the LAN Manager hash of the password in the SAM.

The detail can be found in Security settings

Check for Windows 2000 compatibility which allows access to the domain without any account

A-PreWin2000Anonymous

The purpose is to identify domains which allow access without any account because of a Pre-Windows 2000 compatibility

When a Windows 2003 DC is promoted, a pre-Windows 2000 compatibility setting can be enabled through the wizard. If it is enabled, the wizard will add "Everyone" and "Anonymous" to the pre-Windows 2000 compatible access group, and by doing so, it will authorize the domain to be queried without an account (null session)
It is possible to verify the results provided by the PingCastle solution by using a Kali distribution. You should run [rpcclient -U " target_ip_address] and press enter at the password prompt to finally type [enumdomusers].

Remove the "Everyone" and "Anonymous" from the PreWin2000 group while making sure that the group "Authenticated Users" is present, then reboot each DC

5 points if present

https://msdn.microsoft.com/en-us/library/cc223672.aspx
[MITRE]T1110.003 Brute Force: Password Spraying
[FR]ANSSI - The "Pre - Windows 2000 Compatible Access" group includes "Anonymous" (vuln2_compatible_2000_anonymous)2
[US]STIG V-8547 - The Anonymous Logon and Everyone groups must not be members of the Pre-Windows 2000 Compatible Access group.

Check that the "Pre-Windows 2000 Compatible Access" group has not being modified from its default

A-PreWin2000Other

The purpose is check that no additional account has been added to the "Pre-Windows 2000 Compatible Access" group

The pre-Windows 2000 compatible access group grants access to some RPC calls which should not be available to users or computers.

Remove the members from the PreWin2000 group while making sure that the group "Authenticated Users" is present. Then reboot each DC.

2 points if present

https://msdn.microsoft.com/en-us/library/cc223672.aspx
[MITRE]T1110.003 Brute Force: Password Spraying
[FR]ANSSI - Use of the "Pre-Windows 2000 Compatible Access" group (vuln3_compatible_2000_not_default)3

Check if all DC have no constrained delegation.

P-DelegationDCa2d2

The purpose is to ensure that no contrained delegations are applied to DC

A constrained delegation is a delegation with some limitation.
In this case, it is a limitation of the technical service a delegate can call (SPN).
But in practice, the specific service name is not checked and the delegate can impersonate anyone on all services of a computer.
For the case of a domain controller, that means that the delegate can take the control of the domain by impersonating a domain admin and doing modifications with the LDAP service.
This delegation is set via the attribute msDS-AllowedToDelegateTo and is limited to kerberos
Note: this rule is a companion of the rule P-DelegationDCt2a4d

You should edit the msDS-AllowedToDelegateTo attribute of the accounts listed below to remove the SPN of the domain controllers involved.

25 points per discovery

[FR]ANSSI - Constrained authentication delegation to a domain controller service (vuln1_delegation_a2d2)1
[MITRE]T1187 Forced Authentication
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

The detail can be found in Domain controllers

Check delegations for the recipient's existence

P-UnkownDelegation

The purpose is to verify that each delegation are linked to an account which exists

In the case where a delegation has been created where the account can't be translated to a NT account, it means that the delegation is actually from another domain or that the user has been deleted.

To reduce the risk, the easiest way is essentially to remove the delegation

15 points if present

[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]T1187 Forced Authentication

The detail can be found in Delegations

A Delegation is granted to Everyone

P-DelegationEveryone

The purpose is to verify that there is no delegation granted to "Everyone" and to "Authenticated Users"

To delegate control to a OU, access checks can be modified. In case of a misconfiguration, access can be granted to the group "Everyone" or "Authenticated Users".

Review the delegation to remove this permission and if needed, set a more targeted group as recipient of the delegation.

15 points per discovery

[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]
[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]T1187 Forced Authentication

The detail can be found in Delegations

Check if attributes unixUserPassword and userPassword are set

A-UnixPwd

The purpose is to check if password information may be stored in AD attributes

To perform Single Sign On (SSO) systems need to share secrets with Active Directory.
This is not the case for all systems such as Unix and Mainframe and designers have found a workaround by storing this secret into a user account attribute.
However not all systems did implement a proper and cryptographically safe protocol and they are checking the password submitted in their system with an AD attribute.
At that time, it was not known that these attributes can be queried by everyone and as consequence, they did not enforce a robust protection.
Looking at the attribute unixUserPassword, the password can be retrieved either in clear text (encoded as ASCII) or with a weak algorithm such as ROT 13.

In addition to that, the way to change a password in LDAP system is to modify the value of the special attribute userPassword.
This attribute is not supposed to be visible. However Active Directory is using another attribute named unicodePwd (unless the heuristic fUserPwdSupport is set).
That means that the attribute userPassword is not special anymore and that a change of its value is displayed in clear text, considered as a normal attribute.
A misconfigured application can change the user password using this old mechanism, and as a consequence, set the user password in clear text.

The attribute unixUserPassword and userPassword should be cleared from the mentionned user account, unless the remote system is known to have a strong cryptographic protocol.

Informative rule (0 point)

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-adts/f3adda9f-89e1-4340-a3f2-1f0a6249f1f8
https://www.blackhillsinfosec.com/domain-goodness-learned-love-ad-explorer/
[MITRE]T1552 Unsecured Credentials
[FR]ANSSI - Accounts with passwords stored using reversible encryption (vuln3_reversible_password)3

The detail can be found in Unix Passwords

Find Password GPO

A-PwdGPO

The purpose is to alert when a clear text password has been identified in the GPO. Regardless of whether the password is present or not, both the account and password should be considered compromised

A check is performed to identify passwords in the GPO. If a password is identified through the PingCastle solution, it means that it can be identified through many other means by attackers, and that the account should be considered compromised.
Do note that the AES key used to encrypt passwords in GPOs has been made public for interoperability reasons, which is why even an encrypted password is compromised. It has been revealed in this page

In order to solve this issue, you should manually change the password to a new one. If this password is shared on many systems, each system should have a different password. If the GPO was used to define the native local administrator account, it is recommended to install a password solution manager such as the LAPS solution.

20 points per discovery

https://msdn.microsoft.com/en-us/library/cc422924.aspx
[MITRE]T1552.006 Unsecured Credentials: Group Policy Preferences
[FR]ANSSI CERTFR-2015-ACT-046

The detail can be found in the Obfuscated Passwords

Check if LAPS passwords can be retrieved from computers that has been added manually by users.

A-LAPS-Joined-Computers

The purpose of this rule is to ensure that there is no LAPS permission problems with computers that have been added manually to the domain by a user

By default, every domain user can add up to 10 computers to the domain (see the rule S-ADRegistration for more information).
When a computer is added to the domain, the owner of the computer object is the user who joined the computer.
To trace this insertion, a special attribute mS-DS-CreatorSID is added, whose value is the SID of its creator.
When LAPS is installed, the local admin account has its password stored in a special attribute named, by default, ms-mcs-AdmPwd. Its access is retricted.
Because the user who created it is the owner of the underlying object, it can retrieve the LAPS attribute and get the local admin password.

In addition to check if the owner of the computer object is the user which added it, this program checks also if this user have an explicit permission on this object to write the owner, write the security descriptor, or "all extended rights".
Indeed, the right "all extended rights" allows to read the LAPS password and write access to these attributes can cancel the security hardening of changing the owner.

Review the security of the computer objects listed in the LAPS section below to change their ownership (you can give it to the domain admins group).
Check if the creator has also write permissions to change the owner or the security descriptor and if he has the right "all extended rights" on this object.
If it is the case, remove the permissions granted to this user.

5 points if present

https://azurecloudai.blog/2019/10/01/laps-security-concern-computers-joiners-are-able-to-see-laps-password/
https://www.securityinsider-wavestone.com/2020/01/taking-over-windows-workstations-pxe-laps.html
[MITRE]T1555.005 Credentials from Password Stores: Password Managers

The detail can be found in LAPS

Check for inactive trusts

T-Inactive

The purpose is to verify that every trust has a remote domain which is active.

When a trust is active, it is using a shared secret to communicate to a domain. This secret is hold in a special account whose name is the remote domain name. This password is changed every month and as consequence the whenChanged attribute of this account is changed. When there is no modification of the whenChanged attribute, it can be guessed that the secret has not being changed and that there was either a problem with the remote domain or that the remote domain does not exist anymore.

Check for network connectivity issues from the remote domain or if the remote domain still exists. If it doesn't exist anymore, the trust should be removed. Indeed the secret used by the trust can be used to issue fake kerberos tickets and be used as a backdoor.

20 points if present

https://msdn.microsoft.com/fr-fr/library/ms680921(v=vs.85).aspx
[MITRE]T1557 Man-in-the-Middle
[FR]ANSSI - Trust account passwords unchanged for more than a year (vuln2_trusts_accounts)2

The detail can be found in Trusts section

Check if DNS Zones are configured with unsecure update.

A-DnsZoneUpdate1

The purpose is to ensure that the DNS Zones are configured to accept only secure update.

When the unsecure update mechanism is enabled, an attacker can update a DNS record anonymously.
He can then use this feature to add new entries or perform a man in the middle attack to capture credentials.

Please note that the rule A-DnsZoneUpdate1 is the companion of A-DnsZoneUpdate2 and it is used to report anomalies related to the local domain zone or the main _msdcs zone. A-DnsZoneUpdate2 reports all the other zones.

You have to enable secure updates.
Identify the faulty zone in the details below.
Go to the DNS console and select a zone in the "Forward Lookup Zones".
Right click on it and switch to the "General" tab.
Then change Dynamic updates from "Nonsecure and secure" to "Secure only".
You can also run: dnscmd servername /Config zone /AllowUpdate 2

15 points if present

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dnsp/f97756c9-3783-428b-9451-b376f877319a
https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/dnscmd
[MITRE]T1557 Man-in-the-Middle
[FR]ANSSI - Misconfigured DNS zones (vuln1_dnszone_bad_prop)1

Ensure LDAP signing requirements is not set to None

A-LDAPSigningDisabled

The purpose is to check that the integrity of the network protocol LDAP as not been explicitly disabled.

The LDAP signature feature enables the integrity of the network communication between the computer and the domain controller.
Hackers aim at intercepting the communication at the network layer and modify the network dialog to grant themselves admin privileges.
The goal of this feature is to defeat these attacks.
Unfortunately, not all devices support LDAP signature. That's why the best practice is to Require Signature if possible or to, at least, try to negotiate it.
In this case, the LDAP signature feature is configured to None (no negotiation), which can enable hackers to perform their attacks.

Locate the GPO specified in Details and change the setting in "Network security: LDAP client signing requirements".
Disable this setting, or set it to "Negotiate signing" or "Require Signature".
The setting is located in :
Computer configuration -> Policies -> Windows Settings ->Security Settings -> Local Policies -> Security Options.
As an alternative, the file GptTmpl.inf can be manually edited.

5 points if present

https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/network-security-ldap-client-signing-requirements
[MITRE]T1557 Man-in-the-Middle

The detail can be found in Security settings

DC Vulnerability (SMB v1)

S-SMB-v1

The purpose is to verify if Domain Controller(s) are vulnerable to the SMB v1 vulnerability

The SMB downgrade attack is used to obtain credentials or executing commands on behalf of a user by using SMB v1 as protocol. Indeed, because SMB v1 supports old authentication protocol, the integrity can be bypassed

It is highly recommended by Microsoft to disable SMB v1 whenever it is possible on both client and server side. Do note that if you are still not following best practices regarding the usage of deprecated OS (Windows 2000, 2003, XP, CE), regarding Network printer using SMBv1 scan2shares functionalities, or regarding software accessing Windows share with a custom implementation relying on SMB v1, you should consider fixing this issues before disabling SMB v1, as it will generate additional errors.

10 points if present

https://github.com/lgandx/Responder-Windows
https://blogs.technet.microsoft.com/josebda/2015/04/21/the-deprecation-of-smb1-you-should-be-planning-to-get-rid-of-this-old-smb-dialect
https://docs.microsoft.com/windows-server/storage/file-server/troubleshoot/detect-enable-and-disable-smbv1-v2-v3
[FR]ANSSI CERTFR-2017-ACT-019
[FR]ANSSI CERTFR-2016-ACT-039
[MITRE]T1557.001 Man-in-the-Middle: LLMNR/NBT-NS Poisoning and SMB Relay

The detail can be found in Domain controllers

Hardened Paths weakness

A-HardenedPaths

The purpose is to ensure that there is no weakness related to hardened paths

Two vulnerabilities have been reported in 2015 (MS15-011 and MS15-014) which allows a domain takeover via GPO modifications done with a man-in-the-middle attack.
To mitigate these vulnerabilites, Microsoft has designed a workaround named "Hardened Paths". It forces connection settings to enforce Integrity, Mutual Authentication or Privacy.
By default if this policy is empty, if will enforce Integrity and Mutual Authentication on the SYSVOL or NETLOGON shares.
This rule checks if there have been any overwrite to disable this protection.

You have to edit the Hardened Path section in the GPO.
This section is located in Computer Configuration/Policies/Administrative Templates/Network/Network Provider
Check each value reported here and make sure that entries containing SYSVOL or NETLOGON have RequireIntegrity and RequireMutualAuthentication set to 1.
In addition to that, check entries having the pattern \\DCName\* and apply the same solution.

5 points if present

https://labs.f-secure.com/archive/how-to-own-any-windows-network-with-group-policy-hijacking-attacks/
https://talubu.wordpress.com/2018/02/28/configuring-unc-hardened-access-through-group-policy/
https://adsecurity.org/?p=1405
https://support.microsoft.com/en-us/topic/ms15-011-vulnerability-in-group-policy-could-allow-remote-code-execution-february-10-2015-91b4bda2-945d-455b-ebbb-01d1ec191328
[US]STIG V-63577 - Hardened UNC Paths must be defined to require mutual authentication and integrity for at least the \\*\SYSVOL and \\*\NETLOGON shares.
[MITRE]T1557.001 Man-in-the-Middle: LLMNR/NBT-NS Poisoning and SMB Relay

The detail can be found in the Hardened Paths configuration section.

Check the purpose provided by certificate templates

A-CertTempAnyPurpose

The purpose of this rule is to ensure that there is no certificate template with any purpose that can be requested by anyone

A certificate should define restrictions of its use. It is done via extensions known as EKU (extended key usage).
Without a proper purpose or with the global purpose "Any Purpose" it can be used to enroll certificates on behalf other users and impersonate them using it.

Review the permissions that allow a wide enrollement of this certificate template automatically or specify a specific purpose (EKU)

15 points if present

https://posts.specterops.io/certified-pre-owned-d95910965cd2
https://www.riskinsight-wavestone.com/en/2021/06/microsoft-adcs-abusing-pki-in-active-directory-environment/
[MITRE]T1558 Steal or Forge Kerberos Tickets

The detail can be found in Certificate Templates

Check the if a custom subject can be pushed on an authentication certificate templates

A-CertTempCustomSubject

The purpose of this rule is to ensure that there is no certificate request having an authentication purpose whose subject can be modified

Usually, the subject of a certificate is generated automatically by the certification authority.
By allowing its manual edition before its issuance, a malicious user can set the subject to match an administrator account, and thus get a certificate representing them.
This certificate can be abuse later to impersonate them.

On the certificate template properties, uncheck in the property sheet "Subject Name" the field "Supply in the request".
Or in alternative, restrict this template to a restricted group.

15 points if present

https://posts.specterops.io/certified-pre-owned-d95910965cd2
https://www.riskinsight-wavestone.com/en/2021/06/microsoft-adcs-abusing-pki-in-active-directory-environment/
[MITRE]T1558 Steal or Forge Kerberos Tickets

The detail can be found in Certificate Templates

Check if certificate templates can be edited by everyone.

A-CertTempAnyone

The purpose of this rule is to ensure that there is no certificate template that can be edited by anyone

A certificate template is an object whose definition serves as a base to issue certificates.
If a user has the right to edit it, it can manually change obscure attributes such as msPKI-Certificate-Name-Flag.
Doing so will enable him to provide the subject of the certificate and thus having a certificate on behalf other users such as admins.
It can be used to impersonate them and take control of the domain

Review the security permissions of this certificate template and remove the write access to everyone-like group such as domain user, domain computers, everyone, authenticated users, ...

15 points if present

https://posts.specterops.io/certified-pre-owned-d95910965cd2
https://www.riskinsight-wavestone.com/en/2021/06/microsoft-adcs-abusing-pki-in-active-directory-environment/
[MITRE]T1558 Steal or Forge Kerberos Tickets

The detail can be found in Certificate Templates

Check the permission of agent certificate templates

A-CertTempAgent

The purpose of this rule is to ensure that there is no agent certificate that can be requested by anyone

An Agent certificate is a special certificate used to request certificate on behalf other users.
A template has been detected with the agent EKU and that can be enrolled by a large number of users.

Review the permissions that allow a wide enrollement of this certificate template

15 points if present

https://posts.specterops.io/certified-pre-owned-d95910965cd2
https://www.riskinsight-wavestone.com/en/2021/06/microsoft-adcs-abusing-pki-in-active-directory-environment/
[MITRE]T1558 Steal or Forge Kerberos Tickets

The detail can be found in Certificate Templates

Mitigate golden ticket attack via a regular change of the krbtgt password

A-Krbtgt

The purpose is to alert when the password for the krbtgt account can be used to compromise the whole domain. This password can be used to sign every kerberos ticket. Monitoring it closely often mitigates the risk of golden ticket attacks greatly.

Kerberos is an authentication protocol. It is using to sign its tickets a secret stored as the password of the krbtgt account. If the hash of the password of the krbtgt account is retrieved, it can be use to generate authentication tickets at will.
To mitigate this attack, it is recommended to change the krbtgt password between 40 days and 6 months. If it not the case, every backup done until the last password change of the krbtgt account can be used to emit Golden tickets, compromising the entire domain.
Retrieval of this secret is one of the highest priority in an attack, as this password is rarely changed and offer a long term backdoor.
Also this attack can be performed using the former password of the krbtgt account. That's why the krbtgt password should be changed twice to invalidate its leak.

The password of the krbtgt account should be changed twice to invalidate the golden ticket attack.
Beware: two changes of the krbtgt password not replicated to domain controllers can break these domain controllers You should wait at least 10 hours between each krbtgt password change.

There are several possibilities to change the krbtgt password.
First, a Microsoft script can be run in order to guarantee the correct replication of these secrets. Unfortunately this script supports only English operating systems.
Second, a more manual way is to essentially reset the password manually once, then to wait 3 days, then to reset it again. This is the safest way as it ensures the password is no longer usable by the Golden ticket attack.

50 points if the occurence is greater than or equals than 1464
then 40 points if the occurence is greater than or equals than 1098
then 30 points if the occurence is greater than or equals than 732
then 20 points if the occurence is greater than or equals than 366

https://techcommunity.microsoft.com/t5/core-infrastructure-and-security/faqs-from-the-field-on-krbtgt-reset/ba-p/2367838
https://github.com/microsoft/New-KrbtgtKeys.ps1
https://github.com/PSSecTools/Krbtgt
[MITRE]T1558.001 Steal or Forge Kerberos Tickets: Golden Ticket
[FR]ANSSI CERTFR-2014-ACT-032
[FR]ANSSI - Krbtgt account password unchanged for more than a year (vuln2_krbtgt)2

The detail can be found in Krbtgt

Check if admin accounts are vulnerable to the kerberoast attack.

P-Kerberoasting

The purpose is to ensure that the password of admin accounts cannot be retrieved using the kerberoast attack.

To access a service using kerberos, a user does request a ticket (named TGS) to the DC specific to the service.
However this ticket is encrypted using a derivative of the service password. This ticket can then be brute-forced to retrieve the original password.
Any account having the attribute SPN populated is considered as a service account.
Given the fact that any user can request a ticket for service account, these accounts can have their password retrieved.
In addition, services are known to have their password not changed at a regular basis and to use well-known words.

Please note that this program skips service accounts having their password changed for less than 40 days ago to allow a mitigation using a password change process.

If the account is a service account, the service should be removed from the privileged group or have a process to change it at a regular basis.
If the user is a person, the SPN attribute of the account should be removed.

5 points per discovery

https://adsecurity.org/?p=3466
[FR]ANSSI - Privileged accounts with SPN (vuln1_spn_priv)1
[MITRE]T1558.003 Steal or Forge Kerberos Tickets: Kerberoasting

The detail can be found in Admin Groups

Check the use of Kerberos with weak encryption (DES algorithm)

S-DesEnabled

The purpose is to verify that no weak encryption algorithm such as DES is used as crypto algorithm.

DES is very weak algorithm and once assigned to an account, it can be used in Kerberos ticket requests, even though it is easily breakable. It represents a security risk for the kerberos ticket, therefore for the whole AD.

It is recommended to disable DES as an encyrption algorithm in the user configuration dialog or in the "msDSSupportedEncryptionTypes" attribute at LDAP level. It has to be disabled in the property of an account by unchecking the box "Use Kerberos DES encryption for this account"

15 points if present

https://docs.microsoft.com/en-us/archive/blogs/openspecification/msds-supportedencryptiontypes-episode-1-computer-accounts
[FR]ANSSI - Use of Kerberos with weak encryption (vuln2_kerberos_properties_deskey)2
[MITRE]T1558.004 Steal or Forge Kerberos Tickets: AS-REP Roasting

The detail can be found in User information and Computer information

Check if all admin accounts do support kerberos pre-authentication

S-NoPreAuthAdmin

The purpose is to ensure that all admin accounts do support kerberos pre-authentication

Without kerberos pre-authentication, an attacker can request kerberos data from the domain controller and use this data to brute-force the account password. You can search accounts using the ldap query (userAccountControl:1.2.840.113556.1.4.803:=4194304)

Edit the property of the involved accounts and select the Account tab. Uncheck "Do not require Kerberos preauthentication". For computers which doesn't have the Account tab, you have to manually edit the attribute useraccountcontrol. Subtract from the attribute the value 4194304.

5 points per discovery

http://www.harmj0y.net/blog/activedirectory/roasting-as-reps/
[MITRE]T1558.004 Steal or Forge Kerberos Tickets: AS-REP Roasting
[FR]ANSSI - Kerberos pre-authentication disabled for privileged accounts (vuln1_kerberos_properties_preauth_priv)1

The detail can be found in User information and Computer information

Check if DNS Zones are configured with Zone Transfers.

A-DnsZoneTransfert

The purpose is to ensure that no DNS Zones are configured with Zone Transfers.

When the Zone Transfers mechanims is enabled, an attacker can retrieve all DNS records anonymously.
He can then use this feature to generate network noise to trigger a man in the middle attack and capture credentials.

This setting is domain wide, meaning that all servers share the same setting.
Please note that PingCastle does this check to only one DNS Server of the zone.

To test if the Zone Transfers is enabled, issue the following command:
on Linux:

host -t axfr domain.name dns-server

dig axfr @dns-server domain.name

nslookup

server dns-server

set type=any

ls -d domain.name

You have to disable Zone Transfers.
Identify the faulty zone in the details below.
Go to the DNS console and select a zone in the "Forward Lookup Zones".
Right click on it and switch to the "Zone Transfers" tab.
Then ensure "Allow zone transfers" is not enabled "To any server".
You can also run: dnscmd /zoneresetsecondaries zone /noxfr

5 points if present

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dnsp/f97756c9-3783-428b-9451-b376f877319a
https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/dnscmd
[MITRE]T1018 Remote System Discovery

Check if there is a control path involving everyone-like groups.

P-ControlPathIndirectEveryone

The purpose is to ensure that there is no control path involving everyone.

If you have access to a key server and the helpdesk can reset your password, then the helpdesk has access to the key server.
This is the kind of logic used by hackers to take control of the domain using key infrastructure objects (domain root, ...) or groups (domain administrators, ...).
Permissions are collected and analyzed to produce a control paths analysis.
Only write permissions (and specific ones) are used for this analysis.
Then the program identifies which users or computers, that are not members of known groups, can take control of this object.
To be fast, some tradeoffs have been selected. For example, logged on users on servers are ignored.
The program may also select paths which are not exploitable and ignore paths if it cannot read every permissions.
[Everyone] includes the anonymous, everyone, authenticated users, domain users, domain computers and builtin-users groups.

You should analyze the chart and determine which underlying object is involved and grants write permissions to everyone.
Then edit the permissions and locate the write permission involved.
Then delete it or replace it according to your delegation model.

25 points if present

https://github.com/BloodHoundAD/BloodHound
https://github.com/ANSSI-FR/AD-control-paths
[MITRE]T1069.002 Permission Groups Discovery: Domain Groups

The detail can be found in Control Paths Analysis

Check if NetCease has been put in place to mitigate Bloodhound

A-NoNetSessionHardening

The purpose is to ensure that mitigations are in place against the Bloodhound tool

By default, Windows computers allow any authenticated user to enumerate network sessions to it.
This means an attacker could enumerate network sessions to a file share hosting home directories or a Domain Controller to see who’s connected to SYSVOL (to apply Group Policy) and determine which workstations each user and admin account is logged into.
Bloodhound uses this capability extensively to map out credentials in the network.

Disabling Net Session Enumeration removes the capability for any user to enumerate net session info (Recon).

If this mitigation is not part of the computer image, apply the following recommandations:
Run the NetCease PowerShell script (referenced below) on a reference workstation.
Open the Group Policy Management Console. Right-click the Group Policy object (GPO) that should contain the new preference item, and then click Edit .
In the console tree under Computer Configuration, expand the Preferences folder, and then expand the Windows Settings folder.
Right-click the Registry node, point to New, and select Registry Wizard.
Select the reference workstation on which the desired registry settings exist, then click Next .
Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\DefaultSecurity\
and select the check box for “SrvsvcSessionInfo” from which you want to create a Registry preference item. Select the check box for a key only if you want to create a Registry item for the key rather than for a value within the key.
Click Finish.
The settings that you selected appear as preference items in the Registry Wizard Values collection

Informative rule (0 point)

https://github.com/p0w3rsh3ll/NetCease
https://adsecurity.org/?p=3299
[MITRE]T1087.001 Account Discovery: Local Account

The detail can be found in Security settings

Check for Short password length in password policy

A-MinPwdLen

The purpose is to verify if the password policy of the domain enforces users to have at least 8 characters in their password

A check is performed to identify if the GPO regarding password policy allows less than 8 characters password. Short passwords represents a high risk because they can fairly easily be brute-forced. Most CERT and agencies advises for at least 8 characters (and often this number goes up to 12)

To solve the issue, the best way is to either remove the GPO enabling short password, or to modify it in order to increase the password length to at least 8 characters

10 points if present

https://www.microsoft.com/en-us/research/publication/password-guidance/
[MITRE]T1201 Password Policy Discovery
[FR]ANSSI - Privileged group members with weak password policy (vuln2_privileged_members_password)2

The detail can be found in Password policies

Check the Password Policy for Service Accounts (Information)

A-NoServicePolicy

The purpose is to give information regarding a best practice for the Service Account password policy. Indeed, having a 20+ characters password for this account greatly helps reducing the risk behind Kerberoast attack (offline crack of the TGS tickets)
Note: PSO (Password Settings Objects) will be visible only if the user which collected the information has the permission to view it.

The rule is purely informative, as it gives insights regarding a best practice. It verifies if there is a GPO or PSO enforcing a 20+ characters password for the Service Account.

The recommended way to handle service accounts is to use "Managed service accounts" introduced since Windows 2008 R2 (search for "msDS-ManagedServiceAccount").
To solve the anomaly, you should implement a PSO or GPO password guarantying a 20+ length password.

Informative rule (0 point)

https://www.microsoft.com/en-us/research/publication/password-guidance/
[MITRE]T1201 Password Policy Discovery

The detail can be found in Password Policies

Check that the "Pre-Windows 2000 Compatible Access" group does not contain "Authenticated Users"

A-PreWin2000AuthenticatedUsers

The purpose is check if the "Pre-Windows 2000 Compatible Access" group contains authenticated users

The pre-Windows 2000 compatible access group grants access to some RPC calls.
Its default and secure value is the "Authenticated Users" group which allows users to perform group look up using legacy protocols.

If this group contains "Authenticated Users", it increases the impact on the exploitation vulnerability on legacy protocols such as the printer spooler.
Indeed, in the #PrintNightmare attack, it enables a patch bypass on domain controllers because the property Elevated Token is on when establishing a session to the DC.
Removing the group can have side impacts and as a consequence, this is reported here as a special hardening measure.

Remove "authenticated users" from the PreWin2000 group.

Informative rule (0 point)

https://msdn.microsoft.com/en-us/library/cc223672.aspx
https://www.gradenegger.eu/?p=1132
[MITRE]T1210 Exploitation of Remote Services

Ensure that dangerous privileges are not granted to everyone by GPO

P-PrivilegeEveryone

The purpose is to ensure that standard users are not granted dangerous privileges

To perform special operations, the operating system relies on privileges. They can be displayed by running the command: whoami /all.
SeLoadDriverPrivilege can be used to take control of the system by loading a specifically designed driver. This procedure can be performed by low privileged users as the driver can be defined in HKCU.
SeTcbPrivilege is the privilege used to "Act on behalf the operating system". This is the privilege reserved to the SYSTEM user. This procedure allow any users to act as SYSTEM.
SeDebugPrivilege is the privilege used to debug program and to access any program's memory. It can be used to create a new process and set the parent process to a privileged one.
SeRestorePrivilege can be used to modify a service running as local system and startable by all users to a chosen one.
SeBackupPrivilege can be used to backup Windows registry and use third party tools for extracting local NTLM hashes.
SeTakeOwnershipPrivilege can be used to take ownership of any secureable object in the system including a service registry key. Then to change its ACL to define its own service running as LocalSystem.
SeCreateTokenPrivilege can be used to create a custom token with all privileges and thus be abused like SeTcbPrivilege
SeImpersonatePrivilege and SeAssignPrimaryTokenPrivilege can be abused to impersonate privileged tokens. These tokens can be retrieved by establishing security context such as Local DCOM DCE/RPC reflexion.
SeSecurityPrivilege can be use to clear the security event log and shrink it to make events flushed soon. Also read security log and view events where the user inverted the login and its password.
SeManageVolumePrivilege can be use to reset the security descriptor on the C volume and thus, change the inherited permissions to critical files

Locate the GPO specified in Details and remove the privilege.
Most of the settings are located in :
Computer configuration -> Policies -> Windows Settings ->Security Settings -> Local Policies -> User Rights Assignment.
As an alternative, the file GptTmpl.inf can be manually edited.

15 points per discovery

https://www.romhack.io/slides/RomHack%202018%20-%20Andrea%20Pierini%20-%20whoami%20priv%20-%20show%20me%20your%20Windows%20privileges%20and%20I%20will%20lead%20you%20to%20SYSTEM.pdf
https://www.tarlogic.com/en/blog/abusing-seloaddriverprivilege-for-privilege-escalation/
https://github.com/decoder-it/psgetsystem
https://twitter.com/0gtweet/status/1303427935647531018?s=20
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

The detail can be found in Privileges

Check for Trusts whose security is not maximum

T-SIDFiltering

The purpose is to check if all trusts are protected using the functionality named SID Filtering

SID Filtering is a mechanism used to block account presenting a SID History property. SID History is used to link an existing account to another account and can be use to propagate a compromise through trusts. SID Filtering for domain to domain trust is called a quarantine and is disabled by default. SID Filtering to a forest is enabled by default and disabling it is called "enabling SID History".

The algorithm to compute the SID Filtering is:
get the attribute trustDirection and TrustAttributes of the trust object.
if the direction is 0 or 1 or if the trust is intra forest (trustattributes & 32 != 0) then SID Filtering is not applicable.
Then, if the trust is a forest trust (trusattributes & 8 != 0) then
check if /enablesidhistory has been enabled - trustattributes & 64 != 0.
If enabled: SID Filtering is deactivated.
Else if not a forest trust (trustattributes & 8 == 0) then check for the quarantined attribute (trustattributes & 4 != 0).
If the quarantine flag is set, SID Filtering is enabled.

You can use the PowerShell command to get its status:
[System.DirectoryServices.ActiveDirectory.Domain]::GetCurrentDomain().GetSidFilteringStatus('my.domain.to.test.local')

A trust without SID Filtering means either that a migration is in progress or that the domain can be compromised instantly via the trust.
The solution is to complete existing migration ASAP and enable the SID Filtering feature

If the trust is a domain trust, you should use netdom /quarantine and set it to yes
If the trust is a forest trust, you should use netdom /enablesidhistory and set it to no
Do not apply /quarantine on a forest trust: you will break the transitivity of the trust.

100 points if the occurence is greater than or equals than 4
then 80 points if the occurence is greater than or equals than 2
then 50 points if present

https://msdn.microsoft.com/en-us/library/cc237940.aspx
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R16 [paragraph.3.3.1.6]
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[MITRE]T1134.005 Access Token Manipulation: SID-History Injection
[US]STIG V-8538 - Security identifiers (SIDs) must be configured to use only authentication data of directly trusted external or forest trust.
[FR]ANSSI - Unfiltered outbound domain trust relationship (vuln1_trusts_domain_notfiltered)1
[FR]ANSSI - Outbound forest trust relationships with sID History enabled (vuln1_trusts_forest_sidhistory)1

The detail can be found in Trusts section

Check for local backdoor stored in SID History

T-SIDHistorySameDomain

The purpose is to ensure that accounts are not linked for more privileged accounts in the same domain

SID History is an attribute used in migration to link with a former account. It is not possible to have an account linked with an account belonging to the same domain. This can be analyzed by comparing the domain part of the SID History with the domain SID.

It is not possible to have this occurrence except if a user from domain A has been migrated to domain B and then migrated again to domain A. This should be strongly investigated as it may be linked to a compromise of the domain.

50 points if present

[MITRE]T1134.005 Access Token Manipulation: SID-History Injection
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R15 [paragraph.3.3.1.5]
[FR]ANSSI - Accounts or groups with SID history set (vuln3_sidhistory_present)3
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

Ensure that GPO items cannot be modified by any user

P-DelegationGPOData

The purpose is to ensure that standard users cannot modify GPO

When the group Authenticated Users, Everyone or any similar groups have permission to modify a GPO, it can be abused to take control of the accounts where this GPO applies. It can potentially lead to the compromise of the domain

Edit the Access Control List (ACL) of the GPO object or the directory where the items is located. Then remove any write permission given to the group.

15 points per discovery

[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]

Ensure that all login scripts cannot be modified by any user

P-DelegationLoginScript

The purpose is to ensure that standard users cannot modify login scripts

When the group Authenticated Users, Everyone or any similar groups have permission to modify a login script, it can be abused to take control of the accounts using this script. It can potentially lead to the compromise of the domain

Edit the Access Control List (ACL) of the script object or the directory where the file is located. Then remove any write permission given to the group.

15 points per discovery

[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]
[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

The detail can be found in GPO Login script

Check if all DC have no constrained delegation.

P-DelegationDCa2d2

The purpose is to ensure that no contrained delegations are applied to DC

A constrained delegation is a delegation with some limitation.
In this case, it is a limitation of the technical service a delegate can call (SPN).
But in practice, the specific service name is not checked and the delegate can impersonate anyone on all services of a computer.
For the case of a domain controller, that means that the delegate can take the control of the domain by impersonating a domain admin and doing modifications with the LDAP service.
This delegation is set via the attribute msDS-AllowedToDelegateTo and is limited to kerberos
Note: this rule is a companion of the rule P-DelegationDCt2a4d

You should edit the msDS-AllowedToDelegateTo attribute of the accounts listed below to remove the SPN of the domain controllers involved.

25 points per discovery

[FR]ANSSI - Constrained authentication delegation to a domain controller service (vuln1_delegation_a2d2)1
[MITRE]T1187 Forced Authentication
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

The detail can be found in Domain controllers

At least one Administrator Account can be delegated

P-Delegated

The purpose is to ensure that all Administrator Accounts have the configuration flag "this account is sensitive and cannot be delegated" (and are not member of the built-in group "Protected Users" when your domain functional level is at least Windows Server 2012 R2).

Without the flag "This account is sensitive and cannot be delegated" any account can be impersonated by some service account. It is a best practice to enforce this flag on administrators accounts.

To correct the situation, you should make sure that all your Administrator Accounts has the check-box "This account is sensitive and cannot be delegated" active or add your Administrator Accounts to the built-in group "Protected Users" if your domain functional level is at least Windows Server 2012 R2 (some functionalities may not work properly afterwards, you should check the official documentation). Please note that there is a section below in this report named "Admin Groups" which give more information.

20 points if present

[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[US]STIG V-36435 - Delegation of privileged accounts must be prohibited.

The detail can be found in Admin Groups

Check delegations for the recipient's existence

P-UnkownDelegation

The purpose is to verify that each delegation are linked to an account which exists

In the case where a delegation has been created where the account can't be translated to a NT account, it means that the delegation is actually from another domain or that the user has been deleted.

To reduce the risk, the easiest way is essentially to remove the delegation

15 points if present

[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]T1187 Forced Authentication

The detail can be found in Delegations

SIDHistory check

S-SIDHistory

The purpose is to ensure that a migration has been completed correctly and that the SIDHistory attribute has been cleared out from user and computer accounts. This attribute is indeed set when migrating a user or a computer from one domain to another

The SIDHistory attribute is useful when doing a migration because it allows to keep the reference to the former account. On the other hand, once the migration is over, it is mandatory that this attribute is removed to evaluate the permissions in regards with the new account and not the former one.

To solve the security issue, you should remove all the SIDHistory attributes. To do so, you can list the objects having an SIDHistory attribute using the command: get-ADObject -ldapfilter "(sidhistory=*)" -properties sidhistory.
Each security descriptor of the domain (including file shares for example) should be reviewed to be rewritten with the new SID of the account. Then, the attribute can be removed of these accounts using the migration tool or a PowerShell snippet Remove-SIDHistory once the migration is completed. Please note that once the SID History has been removed, it cannot be added back again without doing a real migration. Hopefully hacking tools such as mimikatz can be used to undo a deletion with for example the lsadump::dcshadow attack.

5 points per discovery with a minimal of 15 points

[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[MITRE]T1134.005 Access Token Manipulation: SID-History Injection
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R15 [paragraph.3.3.1.5]

The SIDHistory detail can be found in User information and Computer information and a quick summary in SID History

Check that every account requires a password

S-PwdNotRequired

The purpose is to ensure that every account requires a password

An account can be set without a password if it has the flag "PASSWD_NOTREQD" set as "True" in the "useraccountcontrol" attribute. This represents a high security risk as the account is not protected at all without a password

The best solution to solve the problem is to change the "useraccountcontrol" attribute of all the accounts that have it and that are not used in trusts. If the flag is removed while there is no password set, you will have an error. You can use this to detect accounts without any passwords. Do note that you can manually check all the accounts that need to be worked on using the following PowerShell command: get-adobject -ldapfilter "(&(objectCategory=person)(objectClass=user)(userAccountControl:1.2.840.113556.1.4.803:=32))" -properties useraccountcontrol

15 points if present

https://docs.microsoft.com/troubleshoot/windows-server/identity/useraccountcontrol-manipulate-account-properties
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R36 [subsection.3.6]

The detail can be found in User information and Computer information

Ensure that file deployed by a GPO cannot be modified by everyone.

P-DelegationFileDeployed

The purpose is to check that files deployed to computers cannot be changed by everyone.

Application provided in a msi form or general files can be deployed by a GPO. If an attacker can modify one of this file, it can take control of the user account.

Locate the file mentionned by the GPO specified in Details and change its permissions.

5 points per discovery

[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]

The detail can be found in GPO Deployed Files

A Delegation is granted to Everyone

P-DelegationEveryone

The purpose is to verify that there is no delegation granted to "Everyone" and to "Authenticated Users"

To delegate control to a OU, access checks can be modified. In case of a misconfiguration, access can be granted to the group "Everyone" or "Authenticated Users".

Review the delegation to remove this permission and if needed, set a more targeted group as recipient of the delegation.

15 points per discovery

[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]
[US]STIG V-2370 - The access control permissions for the directory service site group policy must be configured to use the required access permissions.
[MITRE]T1187 Forced Authentication

The detail can be found in Delegations

Check for hidden group membership for computer accounts

S-C-PrimaryGroup

The purpose is to check for unusual value in the primarygroupid attribute used to store group membership

In Active Directory, group membership is stored on the "members" attribute and on the "primarygroupid" attribute.
The default primary group value is "Domain Users" for the users, "Domain Computers" for the computers and "Domain Controllers" for the domain controllers.
The primarygroupid contains the RID (last digits of a SID) of the group targeted. It can be used to store hidden membership as this attribute is not often analyzed.
This rule can also be triggered if one domain controller is not in the default container (named "Domain Controllers" and located at the root) which is not a recommended practice.

Unless strongly justified, change the primary group id to its default. 513 or 514 for users, 516 or 521 for domain controllers, 514 or 515 for computers. The primary group can be edited in a friendly manner by editing the account with the "Active Directory Users and Computers" and after selecting the "Member Of" tab, "set primary group".

15 points if present

[FR]ANSSI - Accounts with modified PrimaryGroupID (vuln3_primary_group_id_nochange)3
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

The detail can be found in User information and Computer information

Check the Allowed RODC Password Replication Group group

P-RODCAllowedGroup

The purpose is to ensure that the Allowed RODC Password Replication Group group is empty.

Accounts belonging to the Allowed RODC Password Replication Group group have their password hashes revealed on all RODCs.

This group should be emptied, and dedicated groups should only be added to the Password Replication Policy of each relevant RODC.

5 points if present

[FR]ANSSI - Dangerous configuration of replication groups for read-only domain controllers (RODCs) (allow) (vuln3_rodc_allowed_group)3
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration

Check the Denied RODC Password Replication Group group

P-RODCDeniedGroup

The purpose is to ensure that the Denied RODC Password Replication Group group has at least its default members.

A set of critical objects are being forbidden to replicate in RODC for security reasons.
This permission is set using the Denied RODC Password Replication Group group.
Removing one of the default members of this group remove this protection, and thus, the isolation of RODC.

Add the items which have been identified as missing to the Denied RODC Password Replication Group group.

5 points if present

https://docs.microsoft.com/en-us/services-hub/health/remediation-steps-ad/review-the-removal-of-default-members-from-the-denied-rodc-password-replication-group
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Dangerous configuration of replication groups for read-only domain controllers (RODCs) (denied) (vuln3_rodc_denied_group)3

Check that there is no account with never-expiring passwords

S-PwdNeverExpires

The purpose is to ensure that every account has a password which is compliant with password expiration policies

Some accounts have passwords which never expire. Should an attacker compromise one of these accounts, he would be able to maintain long-term access to the Active Directory domain.

We have noted that some Linux servers, domain joined, are configured with a password which never expires.
This is a misconfiguration because a password change can be configured. It was however not the default on some plateform.
See one of the link below for more information.

In order to make Active Directory enforce periodic password change, accounts must not have the "Password never expires" flag set in the "Account" tab of the user properties. Their passwords should then be rolled immediately.
For services accounts, Windows provide the "managed service accounts" and "group managed service accounts" features to facilite the automatic change of passwords.
Please note that there is a document in the section below which references solutions for service accounts of well known products.
Also Linux servers should be configured with automatic machine account change.

1 points if present

https://adsecurity.org/?p=4115
https://access.redhat.com/discussions/1283873
[MITRE]Mitre Att&ck - Mitigation - Active Directory Configuration
[FR]ANSSI - Accounts with never-expiring passwords (vuln2_dont_expire)2

The detail can be found in User information

Check for the last backup date according to Microsoft standard

A-BackupMetadata

The purpose is check if the backups are actually up to date in case they are needed. The alert can be triggered when a domain is backed up using non-recommended methods

A verification is done on the backups, ensuring that the backup is performed according to Microsoft standards. Indeed at each backup the DIT Database Partition Backup Signature is updated.  If for any reasons, backups are needed to perform a rollback (rebuild a domain) or to track past changes, the backups will actually be up to date. This check is equivalent to a REPADMIN /showbackup *.

Plan AD backups based on Microsoft standards. These standards depend on the Operating System. For example with the wbadmin utility: wbadmin start systemstatebackup -backuptarget:d:

15 points if the occurence is greater than or equals than 7

https://technet.microsoft.com/en-us/library/jj130668(v=ws.10).aspx
[MITRE]Mitre Att&ck - Mitigation - Data Backup
[US]STIG V-25385 - Active Directory data must be backed up daily for systems with a Risk Management Framework categorization for Availability of moderate or high. Systems with a categorization of low must be backed up weekly.

The detail can be found in Backup

Ensure that the privilege to log on Domain Controllers are not granted to everyone by GPO

P-LoginDCEveryone

The purpose is to ensure that standard users cannot login to Domain Controllers

Domain Controllers are critical components of the Active Directory. If an attacker is able to open a session, he will be able to discover unsecure backup media or perform a local privilege escalation to become the DC admin and thus the AD admin.
Local logon requires usually physical interaction, which explains why network seggregation is a best practice, but this can be bypassed. Indeed VNC or remote server management software is a way to perform local logon remotely.
In addition, remote server management software have been the subject of many vulnerabilites, some of them can be exploited even if this software is disabled.

Locate the GPO specified in Details and remove the privilege "Allow log on locally" or "Allow log on through Remote Desktop Services" to "Everyone", "Authenticated Users", "Domain Users" or "Domain Computers".
The settings are located in :
Computer configuration -> Policies -> Windows Settings ->Security Settings -> Local Policies -> User Rights Assignment.
As an alternative, the file GptTmpl.inf can be manually edited.

15 points per discovery

https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/allow-log-on-locally
https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/allow-log-on-through-remote-desktop-services
https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04197764-1
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R18 [subsubsection.3.3.2]
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The detail can be found in Privileges

Ensure the "automatic administrative logon" feature of the recovery mode is not enabled

P-RecoveryModeUnprotected

The purpose is to check that it is not possible to go into recovery mode without the administrator password

The recovery mode is a special mode allowing an admin to fix an issue preventing the computer to boot. By pressing F8 in the short time span allowed, the computer boots with just a simple command line.
Usually, the administrator password is requested to avoid that people having physical access get control of it. It can typically be done by creating a new user account and add this account as member of the administrators group. This rule checks if there are any GPO which disable this password prompt.

Locate the GPO specified in Details and turn off the setting "Recovery console: Allow automatic administrative logon"
The setting is located in :
Computer configuration -> Policies -> Windows Settings ->Security Settings -> Local Policies -> Security Options.
As an alternative, the file GptTmpl.inf can be manually edited.

15 points if present

https://docs.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/recovery-console-allow-automatic-administrative-logon
[US]STIG V-1159 - The Recovery Console option is set to permit automatic logon to the system.
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The detail can be found in Security settings

Check for suspicious account(s) used in administrator activities

A-AdminSDHolder

The purpose is to ensure that there is no rogue admin accounts in the Active Directory

A check is performed on non-admin accounts in order to identify if they have an attribute admincount set. If they have this attribute, it means that this account, which is not supposed to be admin, has been granted administrator rights in the past. This typically happens when an administrator gives temporary rights to a normal account, off process.

These accounts should be reviewed, especially in regards with their past activities and have the admincount attribute removed. In order to identify which accounts are detected by this rule, we advise to run a PowerShell command that will show you all users having this flag set: get-adobject -ldapfilter "(admincount=1)"
Do not forget to look at the section AdminSDHolder below.

50 points if the occurence is greater than or equals than 50
then 45 points if the occurence is greater than or equals than 45
then 40 points if the occurence is greater than or equals than 40
then 35 points if the occurence is greater than or equals than 35
then 30 points if the occurence is greater than or equals than 30
then 25 points if the occurence is greater than or equals than 25
then 20 points if the occurence is greater than or equals than 20
then 15 points if present

https://msdn.microsoft.com/en-us/library/ms675212(v=vs.85).aspx
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R40 [paragraph.3.6.3.1]

The detail can be found in the AdminSDHolder User List

Avoid unexpected schema modifications which could result in domain rebuild

P-SchemaAdmin

The purpose is to ensure that no account can make unexpected modifications to the schema

The group "Schema Admins" is used to give permissions to alter the schema. Once a modification is performed on the schema such as new objects, it cannot be undone. This can result in a rebuild of the domain. The best practice is to have this group empty and to add an administrator when a schema update is required then to remove this group membership.

Remove the accounts or groups belonging to the "schema administrators" group.

10 points if present

[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R13 [subsection.3.2]
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management
[US]STIG V-72835 - Membership to the Schema Admins group must be limited

The detail can be found in Admin Groups

Check if all admin passwords are changed on the field.

P-AdminPwdTooOld

The purpose is to ensure that all admins are changing their passwords at least every 3 years

This rule ensure that passwords of administrator are well managed.

We advised to read the ANSSI guidelines about this, which is quoted in the documentation section below.

10 points if present

[FR]ANSSI - Privileged account passwords age too old (vuln1_password_change_priv)1
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The detail can be found in Admin Groups

At least one Domain controller is not owned correctly

P-DCOwner

The purpose is to perform a review of which accounts have ownership rights on a domain controller and can then modify their permissions

By default, the "Domain Administrators" group or the "Enterprise Administrators" group are set as owners for "Domain Controllers". Nonetheless, in some cases (for instance when the server has been promoted from an existing server), the owner can be a non-admin person which joined the server to the domain. If this person has still rights over this account, it can be used to take ownership over the whole domain. A chain of compromising events can be designed to take control of the domain by including this account.

To solve this security issue, you should change the ownership of the domain controller to match the "Domain Administrators" group.
To control the ownership of domain controller objects, you can use the following PowerShell command:
Get-ADComputer -server my.domain.to.check -LDAPFilter "(&(objectCategory=computer)(|(primarygroupid=521)(primarygroupid=516)))" -properties name, ntsecuritydescriptor | select name,{$_.ntsecuritydescriptor.Owner}.
To change it you can edit the owner of an object using adexplorer.exe. First, locate the DC object then right click to select properties. Open the security tab and press the advanced button. You then have a new dialog with an owner tab. Select the owner and change it for the domain administrators group. You’re done (no reboot needed).

10 points if present

[FR]ANSSI - Incorrect object owners (vuln3_owner)3
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The detail can be found in Domain controllers

Check if the Dns Admins group is not empty

P-DNSAdmin

The purpose is to ensure that the Dns Admin group is not used

Administrators of the DNS Service have the possibility to inject a DLL in this service.
However this service is hosted most of the time in the domain controller and is running as system.
That means that DNS Admins are potentially domain admins.

The security descriptor used to grant admin rights is located on the nTSecurityDescriptor attribute of the object CN=MicrosoftDNS,CN=System.
The "Write All Prop" access right induces the vulnerability.

In this case, the DnsAdmins group is not empty and grant to its user, the possibility to interact with the DNS Service.

You should remove the members of the DNS admin group and do a proper delegation to the specific DNS Zones.

First, grant only "Read Property", "List", "List object" and "Read permssions" to CN=MicrosoftDNS,CN=System to enable access to the RPC service.

Then on each zone (the object in the tree below with the class dnsZone), grant "Read Property", "List", "List object", "Read permissions", "Create Child", "Delete Child", "Delete", "Delete Tree".

5 points if present

https://medium.com/@esnesenon/feature-not-bug-dnsadmin-to-dc-compromise-in-one-line-a0f779b8dc83
https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dnsp/007efcd2-2955-46dd-a59e-f83ae88f4678
[FR]ANSSI - DnsAdmins group members (vuln1_dnsadmins)1
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The detail can be found in Admin Groups

Check if a migration is in progress

S-Domain$$$

The purpose is to ensure that the SID History creation is not enabled

To migrate accounts to another domain, the attribute SID History should be added to the new account. Despite the fact that numerous hacking tools such as mimikatz allows the creation of the SID History attribute, its official creation requires the presence of a special auditing group named DOMAIN-$$$ such as TEST-$$$ for the TEST domain.

If a migration is in progress, declare it in PingCastle so this rule won't be triggered. Else, remove this auditing group. You can locate it by using the LDAP query (sAMAccountName=*$$$)

5 points if present

[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R15 [paragraph.3.3.1.5]
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

Check if there is an explicit delegation on DNS servers.

P-DNSDelegation

The purpose is to ensure that no specific delegation has been setup to manage the Microsoft DNS.

Administrators of the DNS Service have the possibility to inject a DLL in this service.
However this service is hosted most of the time in the domain controller and is running as system.
That means that DNS Admins are potentially domain admins.

The security descriptor used to grant admin rights is located on the nTSecurityDescriptor attribute of the object CN=MicrosoftDNS,CN=System.
The "Write All Prop" access right induces the vulnerability.

In this case, an explicit delegation has been setup and this delegation is not using the existing DnsAdmins group.

Rule update:
The Path Tuesday of October 2021 fixed this vulnerability and assigned it the identifier CVE-2021-40469.
If the patch has been applied, there is no additional mitigation to perform.

This rule is transformed into an informative rule in PingCastle 2.10.1 and will be removed in future version of PingCastle.

You should remove the explicit write delegation located in the CN=MicrosoftDNS,CN=System container and do a proper delegation.
First, grant only "Read Property", "List", "List object" and "Read permssions" to CN=MicrosoftDNS,CN=System to enable access to the RPC service.
Then on each zone (the object in the tree below with the class dnsZone), grant "Read Property", "List", "List object", "Read permissions", "Create Child", "Delete Child", "Delete", "Delete Tree".



After the Patch day the Key does exist.

Informative rule (0 point)

https://medium.com/@esnesenon/feature-not-bug-dnsadmin-to-dc-compromise-in-one-line-a0f779b8dc83
https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dnsp/007efcd2-2955-46dd-a59e-f83ae88f4678
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40469
https://blog.0patch.com/2021/11/micropatch-for-remote-code-execution-by.html
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The detail can be found in Delegations

Check for presence of the Protected users group

A-ProtectedUsers

The purpose is to ensure that the schema has been updated for the creation of Protected Users group.

The Protected Users group is a special group which is a very effective mitigation solution to counter attacks using Credential theft starting with Windows 8.1. Older Operating System must be updated to take this protection in account such as the Windows 7 KB2871997 patch.

The Protected Users group is automatically created when the PDC (primary DC) emulator role is transferred to Windows 2012 R2 or newer domain controller. The group is then automatically replicated to all other domain controllers.
Warning: Do not add service account into this group as this will result in "authentication failure" messages. Use "protected accounts" instead

Informative rule (0 point)

https://docs.microsoft.com/en-us/windows-server/security/credentials-protection-and-management/protected-users-security-group
[US]STIG V-78131 - Accounts with domain level administrative privileges must be members of the Protected Users group in domains with a domain functional level of Windows 2012 R2 or higher.
[FR]ANSSI CERTFR-2017-ALE-012
[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management

The schema version is indicated in Domain Information

Check that operators group are empty

P-OperatorsEmpty

The purpose is to ensure that the operator groups, which can have indirect control to the domain, are empty

Operator groups (account operators, server operators, ...) can take indirect control of the domain. Indeed these groups have write access to critical resources of the domain.

It is recommended to have these groups empty. Assign administrators into administrators group. Other accounts should have proper delegation rights in an OU or in the scope they are managing.

Informative rule (0 point)

[MITRE]Mitre Att&ck - Mitigation - Privileged Account Management
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R27 [subsection.3.5]

The detail can be found in Admin Groups

Domain Controller Update

S-DC-NotUpdated

The purpose is to ensure that all the Domain Controllers are updated regularly. This is done by checking if a DC has been rebooted in the past 6 months. If not, it means it has not be patched as well in these 6 monthes

Domain Controller needs to be updated regularly because threats to the AD evolve all the time, so assets in the AD should evolve accordingly. The date of last update is computed by getting the StatisticsStartTime from [net statistics workstation]. If not available, the PingCastle solution will use the lastLogonTimestamp attribute which is refreshed based on the LastLogon attribute. Do note that there is a maximum delay for refresh: 14 days.

Frequently updating the DC should be part of the AD policies, as there should be a dedicated time-slot for the servers to reboot and apply security patches

15 points if present

[MITRE]Mitre Att&ck - Mitigation - Update Software

The detail can be found in Domain controllers

Obsolete OS (Windows 2008)

S-OS-2008

The purpose is to ensure that there is no use of the obsolete and vulnerable OS Windows 2008 for the workstations within the domain

The Windows 2008 OS is not supported any longer, as it is vulnerable to many publicly known exploits: Administrator's credentials can be captured, security protocols are weak, etc.

In order to solve this security issue, you should upgrade all the servers to a more recent version of Windows, starting from Windows 2012. Do note that you can get the full details regarding the OS used with the following PowerShell command: Get-ADComputer -Filter * -Property * | Format-Table Name,OperatingSystem,OperatingSystemServicePack,OperatingSystemVersion -Wrap -Auto You can replace [-Filter *] by [-Filter {OperatingSystem -Like "Windows Server*"}

15 points if the occurence is greater than or equals than 15
then 10 points if the occurence is greater than or equals than 6
then 5 points if present

https://support.microsoft.com/en-us/help/4456235/end-of-support-for-windows-server-2008-and-windows-server-2008-r2
[MITRE]Mitre Att&ck - Mitigation - Update Software
[FR]ANSSI CERTFR-2005-INF-003

The detail can be found in Operating Systems

Obsolete OS (Windows 10)

S-OS-W10

The purpose is to ensure that there is no use of non supported version of Windows 10 within the domain

Some versions of Windows 10 OS is not supported any longer, and may be vulnerable to exploits that are not patched anymore.

In order to solve this security issue, you should upgrade all the Windows 10 to a more recent version.
Do note that you can get the full details regarding the OS used with the following PowerShell command: Get-ADComputer -Filter * -Property * | Format-Table Name,OperatingSystem,OperatingSystemServicePack,OperatingSystemVersion -Wrap -Auto You can replace [-Filter *] by [-Filter {OperatingSystem -Like "Windows 10*"}

15 points if the occurence is greater than or equals than 15
then 10 points if the occurence is greater than or equals than 6
then 5 points if present

https://docs.microsoft.com/en-us/windows/release-health/release-information
[FR]ANSSI CERTFR-2005-INF-003
[MITRE]Mitre Att&ck - Mitigation - Update Software

The detail can be found in Operating Systems

Obsolete Domain Controller (Windows 2008)

S-DC-2008

The purpose is to ensure that there is no use of the obsolete and vulnerable OS Windows 2008 as Domain Controller within the domain

The OS Windows 2008 is not supported anymore by Microsoft (except when migrated to Azure) and any vulnerability found will not be patched unless an expensive support contrat has been purchased.

To resolve this security risk, the only way is to decommission DC running Windows 2008 OS, in order to use new versions that are more secured and that are still being patched regarding new security threats

5 points if present

https://support.microsoft.com/en-us/help/4456235/end-of-support-for-windows-server-2008-and-windows-server-2008-r2
[MITRE]Mitre Att&ck - Mitigation - Update Software
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R12 [subsection.3.1]
[US]STIG V-8551 - The domain functional level must be at a Windows Server version still supported by Microsoft.

The operating system of domain controllers can be found in Domain controllers

Check the process of registration of computers to the domain

S-ADRegistration

The purpose is to ensure that basic users cannot register extra computers in the domain

By default, a basic user can register up to 10 computers within the domain. This default configuration represents a security issue as basic users shouldn't be able to create such accounts and this task should be handled by administrators.

To solve the issue, limit the number of extra computers that can be registered by a basic user. It can be reduced by modifying the value of ms-DS-MachineAccountQuota to zero (0). Another solution can be to remove altogether the authenticated users group in the domain controllers policy. Do note that if you need to set delegation to an account so it can add computers to the domain, it can be done through 2 methods: Delegation in the OU or by assigning the SeMachineAccountPrivilege to a special group

10 points if present

https://docs.microsoft.com/troubleshoot/windows-server/identity/default-workstation-numbers-join-domain
http://prajwaldesai.com/allow-domain-user-to-add-computer-to-domain/
http://blog.backslasher.net/preventing-users-from-adding-computers-to-a-domain.html
[MITRE]Mitre Att&ck - Mitigation - User Account Management

Check if all DC are active.

S-DC-Inactive

The purpose is to ensure that every DC is active.

Domain Controllers are user accounts with powerfull privileges.
While an active Domain Controller change its password every 30 days, an inactive account can be involved in a domain compromise.
Indeed, another account, which have rights over this object, may reset the password of this account without being noticed.

You have to demote the DC object using the procedure referenced in the documentation section.

5 points per discovery

https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/deploy/demoting-domain-controllers-and-domains--level-200-
[FR]ANSSI - Inactive domain controllers (vuln1_password_change_inactive_dc)1
[MITRE]Mitre Att&ck - Mitigation - User Account Management
[FR]ANSSI - Recommandations de sécurité relatives à Active Directory - R45 [paragraph.3.6.6.2]

The detail can be found in Domain controllers