减少xp_sendmail安全漏洞

的用户有权限通过sql mail使用sql server的文件吗？sql mail和 sql代理帐号一样运行在相同安全条件下。默认情况下，sql代理运行在本地系统帐号下。如果用户能存取sql server数据库里的系统扩展存储过程xp_sendmail,那么就会有安全漏洞了。

 
通过给系统扩展存储过程xp_sendmail附加参数，用户就可以获得存取服务器上的文件的权限。通过一个方法你就可以保护xp_sendmail：把它封装倒一个存储过程中去，使附加参数非public。许可受这个存储过程的保护，把许可从xp_sendmail中取消。

下面基本的工作模板，你用它就可以保护xp_sendmail：

use master
go
-- =============================================
-- create procedure basic template
-- =============================================
-- creating the store procedure
if exists (select name
         from     sysobjects
         where    name = n'sp_sendmail'
         and      type = 'p')
    drop procedure sp_sendmail
go

create procedure sp_sendmail
     @in_recipients varchar(8000) = '<default email address>'
    ,@in_message varchar(8000)= 'test'
    ,@in_query varchar(8000)= ''
    ,@in_copy_recipients varchar(8000)= null
    ,@in_blind_copy_recipients varchar(8000)= null
    ,@in_subject varchar(80)= 'test'
    ,@in_type varchar(80)= null
    ,@in_attach_results varchar(80)= null
    ,@in_no_output varchar(8)= null
    ,@in_no_header varchar(8)= null
    ,@in_width int = 10
    ,@in_separator varchar(8)= null
    ,@in_echo_error varchar(8000)= null
    ,@in_set_user varchar(256) = null
    ,@in_dbuse varchar(256) = null
as

declare @attachments varchar(8000)

set @in_recipients = '<default dba email address>;' + @in_recipients
exec master..xp_sendmail
     @recipients = @in_recipients
    ,@message = @in_message
    ,@query = @in_query
    ,@attachments =  ' '
    ,@copy_recipients = @in_copy_recipients
    ,@blind_copy_recipients = @in_blind_copy_recipients
    ,@subject = @in_subject
    ,@type = @in_type
    ,@attach_results = @in_attach_results
    ,@no_output = @in_no_output
    ,@no_header = @in_no_header
    ,@width = @in_width
    ,@separator = @in_separator
    ,@echo_error = @in_echo_error
    ,@set_user = @in_set_user
    ,@dbuse = @in_dbuse
go

-- example to execute the store procedure

execute sp_sendmail
go

-- example to grant permissions to the store procedure

grant execute on sp_sendmail to public
go
revoke execute on xp_sendmail to public
go