.net开放多用SQL Server，在应用时，应该注意那些防止黑客注入攻击？
例如：
         select * from admin where username='XXX' and password='YYY' 的语句,若在正式运行此句之前,如果没有进行必要的字符过滤,则很容易实施SQL注入.

　　如在用户名文本框内输入：abc’ or 1=1-- 在密码框内输入：123 则SQL语句变成：

　　select * from admin where username='abc’ or 1=1 and password='123’ 不管用户输入任何用户名与密码,此语句永远都能正确执行,用户轻易骗过系统,获取合法身份

第一种：
squery=lcase(Request.ServerVariables("QUERY_STRING"))
sURL=lcase(Request.ServerVariables("HTTP_HOST"))

SQL_injdata =":|;|>|<|--|sp_|xp_|\|dir|cmd|^|(|)|+|$|'|copy|format|and|exec|insert|select|delete|update|count|*|%|chr|mid|master|truncate|char|declare"

SQL_inj = split(SQL_Injdata,"|")

For SQL_Data=0 To Ubound(SQL_inj)
if instr(squery&sURL,Sql_Inj(Sql_DATA))>0 Then
Response.Write "SQL通用防注入系统"
Response.end
end if
next


第二种：
SQL_injdata =":|;|>|<|--|sp_|xp_|\|dir|cmd|^|(|)|+|$|'|copy|format|and|exec|insert|select|delete|update|count|*|%|chr|mid|master|truncate|char|declare"

SQL_inj = split(SQL_Injdata,"|")

If Request.QueryString<>"" Then
For Each SQL_Get In Request.QueryString
For SQL_Data=0 To Ubound(SQL_inj)
if instr(Request.QueryString(SQL_Get),Sql_Inj(Sql_DATA))>0 Then
Response.Write "SQL通用防注入系统"
Response.end
end if
next
Next
End If

If Request.Form<>"" Then
For Each Sql_Post In Request.Form
For SQL_Data=0 To Ubound(SQL_inj)
if instr(Request.Form(Sql_Post),Sql_Inj(Sql_DATA))>0 Then
Response.Write "SQL通用防注入系统"
Response.end
end if
next
next
end if

第三种
<%
'--------定义部份------------------
Dim Str_Post,Str_Get,Str_In,Str_Inf,Str_Xh,Str_db,Str_dbstr
'自定义需要过滤的字串,用 "■"分离
Str_In = "'■;■and■exec■insert■select■delete■update■count■*■%■chr■mid■master■truncate■char■declare"
'----------------------------------
%>

<%
Str_Inf = split(Str_In,"■")
'--------POST部份------------------
If Request.Form<>"" Then
For Each Str_Post In Request.Form

For Str_Xh=0 To Ubound(Str_Inf)
If Instr(LCase(Request.Form(Str_Post)),Str_Inf(Str_Xh))<>0 Then
'--------写入数据库----------头-----
Str_dbstr="DBQ="+server.mappath("SqlIn.mdb")+";DefaultDir=;DRIVER={Microsoft Access Driver (*.mdb)};"
Set Str_db=Server.CreateObject("ADODB.CONNECTION")
Str_db.open Str_dbstr
Str_db.Execute("insert into SqlIn(Sqlin_IP,SqlIn_Web,SqlIn_FS,SqlIn_CS,SqlIn_SJ) values('"&Request.ServerVariables("REMOTE_ADDR")&"','"&Request.ServerVariables("URL")&"','POST','"&Str_Post&"','"&replace(Request.Form(Str_Post),"'","''")&"')")
Str_db.close
Set Str_db = Nothing
'--------写入数据库----------尾-----
Response.Write "<Script Language=JavaScript>alert('请不要在参数中包含非法字符尝试注入！');</Script>"
Response.Write "非法操作！系统做了如下记录:<br>"
Response.Write "操作IP："&Request.ServerVariables("REMOTE_ADDR")&"<br>"
Response.Write "操作时间："&Now&"<br>"
Response.Write "操作页面："&Request.ServerVariables("URL")&"<br>"
Response.Write "提交方式：POST<br>"
Response.Write "提交参数："&Str_Post&"<br>"
Response.Write "提交数据："&Request.Form(Str_Post)
Response.End
End If
Next

Next
End If
'----------------------------------

'--------GET部份-------------------
If Request.QueryString<>"" Then
For Each Str_Get In Request.QueryString

For Str_Xh=0 To Ubound(Str_Inf)
If Instr(LCase(Request.QueryString(Str_Get)),Str_Inf(Str_Xh))<>0 Then
'--------写入数据库----------头-----
Str_dbstr="DBQ="+server.mappath("SqlIn.mdb")+";DefaultDir=;DRIVER={Microsoft Access Driver (*.mdb)};"
Set Str_db=Server.CreateObject("ADODB.CONNECTION")
Str_db.open Str_dbstr
Str_db.Execute("insert into SqlIn(Sqlin_IP,SqlIn_Web,SqlIn_FS,SqlIn_CS,SqlIn_SJ) values('"&Request.ServerVariables("REMOTE_ADDR")&"','"&Request.ServerVariables("URL")&"','GET','"&Str_Get&"','"&replace(Request.QueryString(Str_Get),"'","''")&"')")
Str_db.close
Set Str_db = Nothing
'--------写入数据库----------尾-----

Response.Write "<Script Language=JavaScript>alert('请不要在参数中包含非法字符尝试注入！);</Script>"
Response.Write "非法操作！系统做了如下记录:<br>"
Response.Write "操作IP："&Request.ServerVariables("REMOTE_ADDR")&"<br>"
Response.Write "操作时间："&Now&"<br>"
Response.Write "操作页面："&Request.ServerVariables("URL")&"<br>"
Response.Write "提交方式：GET<br>"
Response.Write "提交参数："&Str_Get&"<br>"
Response.Write "提交数据："&Request.QueryString(Str_Get)
Response.End
End If
Next
Next
End If
%>


本篇文章来源于 黑基网-中国最大的网络安全站点 原文链接：http://www.hackbase.com/tech/2011-08-25/65125.html