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。特别式一些特殊字符,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 % |
下面是我写的两种关于解决注入式攻击的防范代码,供大家学习参考!
js版的防范SQL注入式攻击代码~:
[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> [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 Response.Write "<script language=@#javascript@#>" Response.Write "alert(@#非法地址!!@#);" Response.Write "location.href=@#error.asp@#;" Response.Write "<script>" End If %> [CODE END] |
C# 检查字符串,防SQL注入攻击
这个例子里暂定为=号和@#号
bool CheckParams(params object[] args) { string[] Lawlesses={"=","@#"}; if(Lawlesses==null||Lawlesses.Length<=0)return true; //构造正则表达式,例:Lawlesses是=号和@#号,则正则表达式为 .*[=}@#].* (正则表达式相关内容请见MSDN) //另外,由于我是想做通用而且容易修改的函数,所以多了一步由字符数组到正则表达式,实际使用中,直接写正则表达式亦可; String str_Regex=".*["; for(int i=0;i< Lawlesses.Length-1;i++) str_Regex+=Lawlesses[i]+"|"; str_Regex+=Lawlesses[Lawlesses.Length-1]+"].*"; // foreach(object arg in args) { if(arg is string)//如果是字符串,直接检查 { if(Regex.Matches(arg.ToString(),str_Regex).Count>0) return false; } else if(arg is ICollection) //如果是一个集合,则检查集合内元素是否字符串,是字符串,就进行检查 { foreach(object obj in (ICollection)arg) { if(obj is string) { if(Regex.Matches(obj.ToString(),str_Regex).Count>0) return false; } } } } return true; |
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