如果你的查询语句是select * from admin where username=''''"&user&"'''' and password=''''"&pwd&"''''"
那么,如果我的用户名是:1'''' or ''''1''''=''''1
那么,你的查询语句将会变成:
select * from admin where username=''''1 or ''''1''''=''''1'''' and password=''''"&pwd&"''''"
这样你的查询语句就通过了,从而就可以进入你的管理界面。
所以防范的时候需要对用户的输入进行检查。特别是一些特殊字符,比如单引号,双引号,分号,逗号,冒号,连接号等进行转换或者过滤。
需要过滤的特殊字符及字符串有:
net user
xp_cmdshell
/add
exec master.dbo.xp_cmdshell
net localgroup administrators
select
count
Asc
char
mid
''''
:
"
insert
delete from
drop table
update
truncate
from
%
js版的防范SQL注入式攻击的两段代码~:
[CODE START]
<script language="javascript">
<!--
var url = location-.search;
var re=/^\?(.*)(select%20|insert%20|delete%20from%20|count\(|drop%20table|update%20truncate%20|asc\(|mid\(|char\(|xp_cmdshell|exec%20master|net%20localgroup%20administrators|\"|:|net%20user|\''''|%20or%20)(.*)$/gi;
var e = re.test(url);
if(e) {
alert("地址中含有非法字符~");
location-href="error.asp";
}
//-->
<script>
登陆和密码输入判断
//防止非法字符串注入
function checkuseravoid(str){
var inj_str="‘|and|exec|insert|select|delete|update|count|*|%|chr|mid|master|truncate|char|declare|;|or|-|+|,";
var sarray=new Array();
sarray=inj_str.split('|');
for (var i=0 ;i <inj_stra.length ;i++ ) {
if (str.indexOf(inj_stra)>=0)
return true;
}
return false;
}
[CODE END]
asp版的防范SQL注入式攻击代码~:
[CODE START]
<%
On Error Resume Next
Dim strTemp
If LCase(Request.ServerVariables("HTTPS")) = "off" Then
strTemp = "http://"
Else
strTemp = "https://"
End If
strTemp = strTemp & Request.ServerVariables("SERVER_NAME")
If Request.ServerVariables("SERVER_PORT") <> 80 Then strTemp = strTemp & ":" & Request.ServerVariables("SERVER_PORT")
strTemp = strTemp & Request.ServerVariables("URL")
If Trim(Request.QueryString) <> "" Then strTemp = strTemp & "?" & Trim(Request.QueryString)
strTemp = LCase(strTemp)
If Instr(strTemp,"select%20") or Instr(strTemp,"insert%20") or Instr(strTemp,"delete%20from") or Instr(strTemp,"count(") or Instr(strTemp,"drop%20table") or Instr(strTemp,"update%20") or Instr(strTemp,"truncate%20") or Instr(strTemp,"asc(") or Instr(strTemp,"mid(") or Instr(strTemp,"char(") or Instr(strTemp,"xp_cmdshell") or Instr(strTemp,"exec%20master") or Instr(strTemp,"net%20localgroup%20administrators") or Instr(strTemp,":") or Instr(strTemp,"net%20user") or Instr(strTemp,"''''") or Instr(strTemp,"%20or%20") then
JS和C#分别防注入代码
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