ACL Enumeration

Enumerating ACLs with PowerView

Attacker có thể sử dụng PowerView để thực hiện enum ACLs, nhưng sẽ tốn thời gian và độ chính xác không cao. Nếu sử dụng command Find-InterestingDomainAcl thì rất nhiều output trả ra.

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>

Cách khác đó là thực hiện enum target bắt đầu với user mà ta có quyền kiểm soát. Để tìm kiếm hiệu quả, cần thực hiện lấy SID trước.

Import-Module .\PowerView.ps1
$sid = Convert-NameToSid <username>

Sử dụng function Get-DomainObjectACL để thực hiện tìm kiếm tất cả các domain objects có quyền bằng các map SID của user bằng cách sử dụng $sid với property là SecurityIdentifier.

Get-DomainObjectACL -Identity * | ? {$_.SecurityIdentifier -eq $sid}

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

Để map với GUID của ObjectAceFlags, tham khảo: https://learn.microsoft.com/en-us/windows/win32/adschema/control-access-rights

Reverse Search & Mapping to a GUID Value

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

S 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

-ResolveGUIDs Flag

Get-DomainObjectACL -ResolveGUIDs -Identity * | ? {$_.SecurityIdentifier -eq $sid}

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

Create a List of Domain Users

Get-ADUser -Filter * | Select-Object -ExpandProperty SamAccountName > ad_users.txt

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 Use

$sid2 = Convert-NameToSid <username>
Get-DomainObjectACL -ResolveGUIDs -Identity * | ? {$_.SecurityIdentifier -eq $sid2} -Verbose

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

Get-DomainGroup

Get-DomainGroup -Identity <group name> | select memberof

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

Với GenericAll ta có thể:

• Modify group membership

• Force change password

• Thực hiện Kerberoasting attack

Enumerating ACLs with BloodHound

Tìm attack path bằng BloodHound được đánh giá là mạnh hơn PowerView. Lấy các data đã thu thập trước đó từ SharpHound ingestor sau đó upload lên BloodHound. Sử dụng tab Node Info và scroll xuống Outbound Control Rights, option này chỉ show object mà ta có quyền kiểm soát trực tiếp, thông qua group membership và số lượng object mà user này có thể controll qua ACL attack Transitive Object Control.

View Node Info:

Viewing potential attack:

Viewing queries: