SIDHistory check

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

S-1-5-18 [1 object(s)]

Check for hidden group membership for computer accounts

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

In Active Directory, group membersip 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.

Unless stronly 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

https://support.microsoft.com/en-us/help/297951/how-to-use-the-primarygroupid-attribute-to-find-the-primary-group-for

Check the procesuss of registration of computers to the domain

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 set up represents a security issue as basic users shouldn't be able to create such accounts, this task being handled by administrators

To solve the issue, the limit number of extra computers that can be registered by a basic user should 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

http://support.microsoft.com/?id=243327
http://prajwaldesai.com/allow-domain-user-to-add-computer-to-domain/
http://blog.backslasher.net/preventing-users-from-adding-computers-to-a-domain.html

Check for completeness of network declaration

The purpose is to ensure that the minimum set of subnet as been configured in the domain

When multiple sites are created in a domain, networks should be declared in the domain in order to optimize processes such as DC attribution. In addition, PingCastle can collect the information to be able to build a network map. This rule has been triggerd because at least one domain controller has an IP address which was not found in subnet declaration.

Locate the IP address which was found as not being part of declared subnet then add this subnet to the "Active Directory Sites" tool.

5 points if present

Domain Controller WIN-PGAHI2ECI8E ip address fe80::7da2:529:c55a:b931%11

DC Vulnerability (SMB v1)

The purpose is to verify if Domain Controller 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 functionnalities, 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 generates additionnal errors.

1 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
ttps://support.microsoft.com/en-us/help/2696547/how-to-enable-and-disable-smbv1,-smbv2,-and-smbv3-in-windows-vista,-windows-server-2008,-windows-7,-windows-server-2008-r2,-windows-8,-and-windows-server-2012

Domain controller: WIN-PGAHI2ECI8E

Check for Trusts whose security is not maximum

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 to an existing account to another account and can be use to propagage a compromission through trusts. SID Filtering for domain to domain trust is called 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 exisring 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 or equals than 4
then 80 points if the occurence is greater or equals than 2
then 50 points if present

https://msdn.microsoft.com/en-us/library/cc237940.aspx
STIG V-8538

trust without SID Filtering: mil

Check for local backdoor stored in SID History

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 compromission of the domain.

50 points if present

Check for inactive trusts

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 an 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

mil

At least one Administrator Account can be delegated

The purpose is to ensure that all Administrator Accounts have the configuration flag "this account is sensitive and cannot be delegated"

Whitout 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 checkbox "This account is sensitive and cannot be delegated" active.

20 points if present

STIG V-36435

Ensure that all login scripts cannot be modified by any user

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 potentically 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

Script: test.ps1 Account: Authenticated Users Right: Modify, Synchronize

Avoid unexpected schema modifications which could result in domain rebuild

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 pratice 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

STIG V-72835

Find Password GPO

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 password in the GPO 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

GPO: test nfc 2 login: administrator password: vletoux
GPO: test nfc 2 login: adiant password: vletoux
GPO: test nfc 2 login: test password: test

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

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, and 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 recommanded to change the krbtgt password every 40 days. If it not the case, every backups done until the last password change of the krbtgt account can be used to emit Goldent tickets, compromising the entiere 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 also be performed using the former password of the krbtgt account

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
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 essentialy 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 or equals than 732
then 40 points if the occurence is greater or equals than 366
then 30 points if the occurence is greater or equals than 180
then 20 points if the occurence is greater or equals than 70

https://gallery.technet.microsoft.com/Reset-the-krbtgt-account-581a9e51

Check if the LAPS tool to handle the native local administrator password is installed

The purpose is to make sure that there is a proper password policy in place for the native local administrator account.

LAPS (Local Administrator Password Solution) is the advised solution to handle passwords for the native local administrator account on all workstations, as it is a simple way to handle most of the subject.

If you don't have any provisionning process or password solution to manage local administrators, you should install the LAPS solution. If you mitigate the risk differently, you should add this rule as an exception, as the risk is covered.

15 points if present

https://www.microsoft.com/en-us/download/details.aspx?id=46899
STIG V-36438

Check for the last backup date according to Microsoft standard

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 back up using non recommended methods

A verification is done on the backups, ensuring that the backup is performed according to Microsoft standard. 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 *.

Planify backups based on Microsoft standard. These standards depends on the Operating System. Example with the wbadmin utility: wbadmin start systemstatebackup -backuptarget:d:

15 points if the occurence is greater or equals than 7

https://technet.microsoft.com/en-us/library/jj130668(v=ws.10).aspx
STIG V-25385

Check for Short password length in password policy

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 perfomed 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/

Found in GPO Default Domain Policy
Found in GPO Default Domain Controllers Policy
Found in GPO test nfc 2
Found in GPO PSO:test

Retrieve data from the domain without any account

The purpose is to access without any account, aka NULL Sessions, within the Active Directory. A NULL Session is a session opened anonymously to access the AD, often used by attackers to perform a reckon operation on the AD, to identify weaknesses

Unless other rules which check for known cause of anonymous access, this rule try to enumerate accounts from the domain without any account. The program use two methods: MS-SAMR with a NULL connection and MS-LSAT which forces SID resolution with well known SID.
NULL sessions are deactivated by default since Windows 2003 and Windows XP. But for compatibility reasons, a setting enabling them may be still active years after.
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].

Locate other PingCastle rules such as A-PreWin2000Anonymous or A-DsHeuristicsAnonymous which triggered and apply the solutions. You can use the PingCastle scanner mode to do a manual check and proove the extraction of the data.

10 points if present

https://www.sans.org/reading-room/whitepapers/windows/null-sessions-nt-2000-286

DC involved: WIN-PGAHI2ECI8E

Check for Intermediate Certificates using unsafe hashing algorithm (SHA1)

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

Found in GPO NTLMStore Subject is CN=COMODO Code Signing CA 2, O=COMODO CA Limited, L=Salford, S=Greater Manchester, C=GB
Found in GPO NTLMStore Subject is CN=UTN-USERFirst-Object, OU=http://www.usertrust.com, O=The USERTRUST Network, L=Salt Lake City, S=UT, C=US
Found in GPO NTLMStore Subject is CN=COMODO Code Signing CA, O=COMODO CA Limited, L=Salford, S=Greater Manchester, C=GB
Found in GPO GPO:Default Domain Policy;Machine Subject is SERIALNUMBER=200804, CN=Foreigner CA, C=BE
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=UTN-USERFirst-Object, OU=http://www.usertrust.com, O=The USERTRUST Network, L=Salt Lake City, S=UT, C=US
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=COMODO Code Signing CA 2, O=COMODO CA Limited, L=Salford, S=Greater Manchester, C=GB

Check for presence of the Protected users group

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 a Windows 2012 R2 domain controller is installed and upgraded it as PDC (primary DC). The group is then be automatically created and replicated.
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
STIG V-78131

Check for Root Certificates using unsafe hashing algorithm (SHA1)

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

Found in GPO NTLMStore Subject is CN=CA, DC=test, DC=mysmartlogon, DC=com
Found in GPO NTLMStore Subject is CN=MaskTech CSCA, OU=Test Division, O=MaskTech GmbH, C=DE
Found in GPO NTLMStore Subject is CN=Belgium Root CA2, C=BE
Found in GPO NTLMStore Subject is CN=DOD EMAIL CA-29, C=US, O=U.S. Government, OU=DoD, OU=PKI
Found in GPO NTLMStore Subject is CN=AddTrust External CA Root, OU=AddTrust External TTP Network, O=AddTrust AB, C=SE
Found in GPO NTLMStore Subject is CN=CA, DC=test, DC=mysmartlogon, DC=com
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=AddTrust External CA Root, OU=AddTrust External TTP Network, O=AddTrust AB, C=SE
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=Belgium Root CA2, C=BE
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=MaskTech CSCA, OU=Test Division, O=MaskTech GmbH, C=DE
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=CA, DC=test, DC=mysmartlogon, DC=com
Found in GPO GPO:Default Domain Policy;Machine Subject is CN=DOD EMAIL CA-29, C=US, O=U.S. Government, OU=DoD, OU=PKI