减少xp

2022-07-15 80酷酷网 80kuku.com

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