ACL Enumeration

Enumerating ACLs with PowerView

Using Find-InterestingDomainAcl

Don't do it this way becase the info is so big, we might not finish a time boxed assessment

PS C:\htb> Find-InterestingDomainAcl

ObjectDN                : DC=INLANEFREIGHT,DC=LOCAL
AceQualifier            : AccessAllowed
ActiveDirectoryRights   : ExtendedRight
ObjectAceType           : ab721a53-1e2f-11d0-9819-00aa0040529b
AceFlags                : ContainerInherit
AceType                 : AccessAllowedObject
InheritanceFlags        : ContainerInherit
SecurityIdentifier      : S-1-5-21-3842939050-3880317879-2865463114-5189
IdentityReferenceName   : Exchange Windows Permissions
IdentityReferenceDomain : INLANEFREIGHT.LOCAL
IdentityReferenceDN     : CN=Exchange Windows Permissions,OU=Microsoft Exchange Security 
                          Groups,DC=INLANEFREIGHT,DC=LOCAL
IdentityReferenceClass  : group

ObjectDN                : DC=INLANEFREIGHT,DC=LOCAL
AceQualifier            : AccessAllowed
ActiveDirectoryRights   : ExtendedRight
ObjectAceType           : 00299570-246d-11d0-a768-00aa006e0529
AceFlags                : ContainerInherit
AceType                 : AccessAllowedObject
InheritanceFlags        : ContainerInherit
SecurityIdentifier      : S-1-5-21-3842939050-3880317879-2865463114-5189
IdentityReferenceName   : Exchange Windows Permissions
IdentityReferenceDomain : INLANEFREIGHT.LOCAL
IdentityReferenceDN     : CN=Exchange Windows Permissions,OU=Microsoft Exchange Security 
                          Groups,DC=INLANEFREIGHT,DC=LOCAL
IdentityReferenceClass  : group

<SNIP>

Performing a targeted Enumeration

PS C:\htb> Import-Module .\PowerView.ps1
PS C:\htb> $sid = Convert-NameToSid wley

Using Get-DomainObjectACL

Find all domain objects that our user hash rights over

PS C:\htb> Get-DomainObjectACL -Identity * | ? {$_.SecurityIdentifier -eq $sid}

ObjectDN               : CN=Dana Amundsen,OU=DevOps,OU=IT,OU=HQ-NYC,OU=Employees,OU=Corp,DC=INLANEFREIGHT,DC=LOCAL
ObjectSID              : S-1-5-21-3842939050-3880317879-2865463114-1176
ActiveDirectoryRights  : ExtendedRight
ObjectAceFlags         : ObjectAceTypePresent
ObjectAceType          : 00299570-246d-11d0-a768-00aa006e0529
InheritedObjectAceType : 00000000-0000-0000-0000-000000000000
BinaryLength           : 56
AceQualifier           : AccessAllowed
IsCallback             : False
OpaqueLength           : 0
AccessMask             : 256
SecurityIdentifier     : S-1-5-21-3842939050-3880317879-2865463114-1181
AceType                : AccessAllowedObject
AceFlags               : ContainerInherit
IsInherited            : False
InheritanceFlags       : ContainerInherit
PropagationFlags       : None
AuditFlags             : None

Based on the GUID above, we can google or use this command

PS C:\htb> $guid= "00299570-246d-11d0-a768-00aa006e0529"
PS C:\htb> Get-ADObject -SearchBase "CN=Extended-Rights,$((Get-ADRootDSE).ConfigurationNamingContext)" -Filter {ObjectClass -like 'ControlAccessRight'} -Properties * |Select Name,DisplayName,DistinguishedName,rightsGuid| ?{$_.rightsGuid -eq $guid} | fl

Name              : User-Force-Change-Password
DisplayName       : Reset Password
DistinguishedName : CN=User-Force-Change-Password,CN=Extended-Rights,CN=Configuration,DC=INLANEFREIGHT,DC=LOCAL
rightsGuid        : 00299570-246d-11d0-a768-00aa006e0529

Using the steps above is inefficient so we use this command below that has the -ResolveGUIDs flag

Using the -ResolveGUIDs Flag

PS C:\htb> Get-DomainObjectACL -ResolveGUIDs -Identity * | ? {$_.SecurityIdentifier -eq $sid} 

AceQualifier           : AccessAllowed
ObjectDN               : CN=Dana Amundsen,OU=DevOps,OU=IT,OU=HQ-NYC,OU=Employees,OU=Corp,DC=INLANEFREIGHT,DC=LOCAL
ActiveDirectoryRights  : ExtendedRight
ObjectAceType          : User-Force-Change-Password
ObjectSID              : S-1-5-21-3842939050-3880317879-2865463114-1176
InheritanceFlags       : ContainerInherit
BinaryLength           : 56
AceType                : AccessAllowedObject
ObjectAceFlags         : ObjectAceTypePresent
IsCallback             : False
PropagationFlags       : None
SecurityIdentifier     : S-1-5-21-3842939050-3880317879-2865463114-1181
AccessMask             : 256
AuditFlags             : None
IsInherited            : False
AceFlags               : ContainerInherit
InheritedObjectAceType : All
OpaqueLength           : 0

We can do the steps above using Get-Acl and GetADUser cmdlets

Creating a List of Domain Users

PS C:\htb> Get-ADUser -Filter * | Select-Object -ExpandProperty SamAccountName > ad_users.txt

A Useful foreach Loop

PS C:\htb> foreach($line in [System.IO.File]::ReadLines("C:\Users\htb-student\Desktop\ad_users.txt")) {get-acl  "AD:\$(Get-ADUser $line)" | Select-Object Path -ExpandProperty Access | Where-Object {$_.IdentityReference -match 'INLANEFREIGHT\\wley'}}

Path                  : Microsoft.ActiveDirectory.Management.dll\ActiveDirectory:://RootDSE/CN=Dana 
                        Amundsen,OU=DevOps,OU=IT,OU=HQ-NYC,OU=Employees,OU=Corp,DC=INLANEFREIGHT,DC=LOCAL
ActiveDirectoryRights : ExtendedRight
InheritanceType       : All
ObjectType            : 00299570-246d-11d0-a768-00aa006e0529
InheritedObjectType   : 00000000-0000-0000-0000-000000000000
ObjectFlags           : ObjectAceTypePresent
AccessControlType     : Allow
IdentityReference     : INLANEFREIGHT\wley
IsInherited           : False
InheritanceFlags      : ContainerInherit
PropagationFlags      : None

Further Enumeration of Rights Using damundsen

PS C:\htb> $sid2 = Convert-NameToSid damundsen
PS C:\htb> Get-DomainObjectACL -ResolveGUIDs -Identity * | ? {$_.SecurityIdentifier -eq $sid2} -Verbose

AceType               : AccessAllowed
ObjectDN              : CN=Help Desk Level 1,OU=Security Groups,OU=Corp,DC=INLANEFREIGHT,DC=LOCAL
ActiveDirectoryRights : ListChildren, ReadProperty, GenericWrite
OpaqueLength          : 0
ObjectSID             : S-1-5-21-3842939050-3880317879-2865463114-4022
InheritanceFlags      : ContainerInherit
BinaryLength          : 36
IsInherited           : False
IsCallback            : False
PropagationFlags      : None
SecurityIdentifier    : S-1-5-21-3842939050-3880317879-2865463114-1176
AccessMask            : 131132
AuditFlags            : None
AceFlags              : ContainerInherit
AceQualifier          : AccessAllowed

Now we can see that our user damundsen has GenericWrite privileges over the Help Desk Level 1 group. This means, among other things, that we can add any user (or ourselves) to this group and inherit any rights that this group has applied to it. A search for rights conferred upon this group does not return anything interesting.

Let's look and see if this group is nested into any other groups, remembering that nested group membership will mean that any users in group A will inherit all rights of any group that group A is nested into (a member of). A quick search shows us that the Help Desk Level 1 group is nested into the Information Technology group, meaning that we can obtain any rights that the Information Technology group grants to its members if we just add ourselves to the Help Desk Level 1 group where our user damundsen has GenericWrite privileges.

Investigating the Help Desk Level 1 Group with Get-DomainGroup

PS C:\htb> Get-DomainGroup -Identity "Help Desk Level 1" | select memberof

memberof                                                                      
--------                                                                      
CN=Information Technology,OU=Security Groups,OU=Corp,DC=INLANEFREIGHT,DC=LOCAL

Let's recap where we're at:

• We have control over the user wley whose hash we retrieved earlier in the module (assessment) using Responder and cracked offline using Hashcat to reveal the cleartext password value

• We enumerated objects that the user wley has control over and found that we could force change the password of the user damundsen

• From here, we found that the damundsen user can add a member to the Help Desk Level 1 group using GenericWrite privileges

• The Help Desk Level 1 group is nested into the Information Technology group, which grants members of that group any rights provisioned to the Information Technology group

Now let's look around and see if members of Information Technology can do anything interesting. Once again, doing our search using Get-DomainObjectACL shows us that members of the Information Technology group have GenericAll rights over the user adunn, which means we could:

• Modify group membership

• Force change a password

• Perform a targeted Kerberoasting attack and attempt to crack the user's password if it is weak

Investigating the Information Technology Group

PS C:\htb> $itgroupsid = Convert-NameToSid "Information Technology"
PS C:\htb> Get-DomainObjectACL -ResolveGUIDs -Identity * | ? {$_.SecurityIdentifier -eq $itgroupsid} -Verbose

AceType               : AccessAllowed
ObjectDN              : CN=Angela Dunn,OU=Server Admin,OU=IT,OU=HQ-NYC,OU=Employees,OU=Corp,DC=INLANEFREIGHT,DC=LOCAL
ActiveDirectoryRights : GenericAll
OpaqueLength          : 0
ObjectSID             : S-1-5-21-3842939050-3880317879-2865463114-1164
InheritanceFlags      : ContainerInherit
BinaryLength          : 36
IsInherited           : False
IsCallback            : False
PropagationFlags      : None
SecurityIdentifier    : S-1-5-21-3842939050-3880317879-2865463114-4016
AccessMask            : 983551
AuditFlags            : None
AceFlags              : ContainerInherit
AceQualifier          : AccessAllowed

Finally, let's see if the adunn user has any type of interesting access that we may be able to leverage to get closer to our goal.

Looking for Interesting Access

PS C:\htb> $adunnsid = Convert-NameToSid adunn 
PS C:\htb> Get-DomainObjectACL -ResolveGUIDs -Identity * | ? {$_.SecurityIdentifier -eq $adunnsid} -Verbose

AceQualifier           : AccessAllowed
ObjectDN               : DC=INLANEFREIGHT,DC=LOCAL
ActiveDirectoryRights  : ExtendedRight
ObjectAceType          : DS-Replication-Get-Changes-In-Filtered-Set
ObjectSID              : S-1-5-21-3842939050-3880317879-2865463114
InheritanceFlags       : ContainerInherit
BinaryLength           : 56
AceType                : AccessAllowedObject
ObjectAceFlags         : ObjectAceTypePresent
IsCallback             : False
PropagationFlags       : None
SecurityIdentifier     : S-1-5-21-3842939050-3880317879-2865463114-1164
AccessMask             : 256
AuditFlags             : None
IsInherited            : False
AceFlags               : ContainerInherit
InheritedObjectAceType : All
OpaqueLength           : 0

AceQualifier           : AccessAllowed
ObjectDN               : DC=INLANEFREIGHT,DC=LOCAL
ActiveDirectoryRights  : ExtendedRight
ObjectAceType          : DS-Replication-Get-Changes
ObjectSID              : S-1-5-21-3842939050-3880317879-2865463114
InheritanceFlags       : ContainerInherit
BinaryLength           : 56
AceType                : AccessAllowedObject
ObjectAceFlags         : ObjectAceTypePresent
IsCallback             : False
PropagationFlags       : None
SecurityIdentifier     : S-1-5-21-3842939050-3880317879-2865463114-1164
AccessMask             : 256
AuditFlags             : None
IsInherited            : False
AceFlags               : ContainerInherit
InheritedObjectAceType : All
OpaqueLength           : 0

<SNIP>

The output above shows that our adunn user has DS-Replication-Get-Changes and DS-Replication-Get-Changes-In-Filtered-Set rights over the domain object. This means that this user can be leveraged to perform a DCSync attack

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Enumerating ACLs with Bloodhound

Set the wley user as our starting node, select the Node Info tab and scroll down to Outbound Control Rights. This option will show us objects we have control over directly, via group membership, and the number of objects that our user could lead to us controlling via ACL attack paths under Transitive Object Control.

If we click on the 1 next to First Degree Object Control, we see the first set of rights that we enumerated, ForceChangePassword over the damundsen user.

Viewing Node Info through BloodHound

image

If we right-click on the line between the two objects, a menu will pop up. If we select Help, we will be presented with help around abusing this ACE, including:

• More info on the specific right, tools, and commands that can be used to pull off this attack

• Operational Security (Opsec) considerations

• External references.

Investigating ForceChangePassword Further

image

If we click on the 16 next to Transitive Object Control, we will see the entire path that we painstakingly enumerated above. From here, we could leverage the help menus for each edge to find ways to best pull off each attack.

Viewing Potential Attack Paths through BloodHound

image

Finally, we can use the pre-built queries in BloodHound to confirm that the adunn user has DCSync rights.

Viewing Pre-Build queries through BloodHound

image