◆在ASP编程中，身份认证可以说是常要用到......
在ASP编程中，身份认证可以说是常要用到的。但怎么样才能做到认证的安全呢？
举例：
表单提交页面：sub.htm
管理员登陆＜/title> <br><body> <br><form name="form1" method="post" action="sub.asp"> <br><p> 管理员: <br><input type="text" name="UserID" size="25" maxlength="20"><br>密 码: <br><input type="text" name="Pass" size="12" maxlength="20"> <br><input type="submit" name="Submit" value="提交"> <br></p> <br></form> <br></body> <br></html> <br><br>SUB.asp程序 <br><% <br>接收表单中的数据 <br>user=request.from("UserID") <br>检察表单提交的数据是否为空(表单页面可能你用JAVASCRIPT OR VBSCRIPT控制了，但这里也不要忘记控制！ <br>if user="" then <br>转到出错提示页面！ <br>response.redirect "err1.htm" <br>这一句可能没用，但加上为好！ <br>response.end <br>end if <br>pass=request.from("Pass") <br>if pass="" then <br>response.redirect "err2.htm" <br>response.end <br>end if <br>联接数据库 <br>file=server.mappath("你的数据库") <br>set conn=server.createobject("adodb.connection") <br>dr="driver={microsoft access driver (*.mdb)};dbq="&file <br>conn.open dr <br>set rs=server.createobject("adodb.recordset") <br>关键是这里的SQL语言 <br>sql="select * from 表 where user= "&user&" and pass= "&pass&" " <br>rs.open sql <br>if not rs.eof then <br>找到的话就进入管理页面 <br>reponse.redirect "login.asp" <br>else <br>没找到就进入错误页面 <br>response.write "err3.htm" <br>end if <br>%> <br>大家感觉以上代码应该没问题啊，但是这里有一个严重的安全隐患：<br>我如果想登录管理员的话可以在SUb.htm表单输入框中输入： <br>第一个文本框中输入：a or 1 = 1 或 OR = <br>第二个文本框中输入：a or 1 = 1 或 OR = <br>提交，大家会看到...“呜，听我说完好不好，砖头一会再丢过来..." <br>"a " 和“1”为任意字符 <br>有人会问为什么你输入这些字符会以管理员身份进入呢？？ <br>其实这些字符是对你程序中SQL语言的欺骗，而成功进入的 <br>大家看：开始程序SQL中是对表进行查询满足user= "&user&" and pass= "&pass&" "条件的记录 <br>sql="select * from 表 where user= "&user&" and pass= "&pass&" " <br>我而输入上面的代码后就成了： <br>sql="select * from 表 where user= a or 1 = 1 and pass= a or 1 = 1 " <br>大家看看，能有不进入的理由吗？？给我一个不进入的理由，先！ <br>以上USER PASS字段为字符型 如果是数字型也一样的道理！ <br><br>解决方法： <br>一、函数替代法： <br>用REPLACE将用户端输入的内容中含有特殊字符进行替换，达到控制目的啊！：） <br>sql="select * from 表 where user= "&replace(user," "," ")&" and pass= "&replace(pass," "," ")&" " <br>这种方法每次只能替换一个字符，其实危险的字符不只是" "，还有如">"、"<"、"&"、"%"等字符应该全控制起来。但用REPLACE函数好象不太胜任那怎么办呢？？ <br>二、程序控制法 <br>用程序来对客户端输入的内容全部控制起来，这样能全面控制用户端输入的任何可能的危险字符或代码，我就的这个方法！：） <br>举例说明： <br><% <br>捕捉用户端提交的表单内容 <br>user=request.from("user") <br>pass=request.from("pass") <br>... <br>循环控制开始 <br>for i=1 to len(user) <br>用MID函数读出变量user中i 位置的一个字符 <br>us=mid(user,i,1) <br>将读出的字符进行比较 <br>if us=" " or us="%" or us="<" or us=">" or us="&" then <br>如果含有以上字符将出错提示，不能含有以上特殊字符 <br>response.redirect "err2.htm" <br>response.end <br>end if <br>next <br>... <br>%> <br></td></tr></table>
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