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  • SQL Server手注之延时型时间盲注

    近来处理安全问题遇到的sql注入:

    延时函数 WAITFOR DELAY

    WAITFOR是SQL Server中Transact-SQL提供的⼀个流程控制语句。它的作⽤就是等待特定时间,然后继续执⾏后 续的语句。它包含⼀个参数DELAY,⽤来指定等待的时间。

    如果将该语句成功注⼊后,会造成数据库返回记录和 Web请求也会响应延迟特定的时间。由于该语句不涉及条件判断等情况,所以容易注⼊成功。根据Web请求是否有延迟,渗透测试⼈员就可以判断⽹站是否存在注⼊漏洞。同时,由于该语句并不返回特定内容,所以它也是盲注的重要检测⽅法。

    语法:

    WAITFOR DELAY '0:0:n'

    ⽰例:

    WAITFOR DELAY '0:0:4' --  表⽰延迟4秒

    IF exists ()⼦句

    语法:

    IF exists () WAITFOR DELAY '0:0:5'

    手工延时注入

    1.判断是否存在注⼊

    WAITFOR DELAY '0:0:4'

    2.猜测数据库名

    猜测数据库名是否存在

    if ((select count(*) from master.dbo.sysdatabases where dbid=5)=1) waitfor delay '0:0:3'--

    这条语句的意思呢是判断dibd=6的数据库是否存在!如果存在那么就延迟3秒返回!

    根据dbid猜库名,先猜出长度

    if ((select count(*) from master.dbo.sysdatabases where dbid=5 and len(name)=4)=1) waitfor delay '0:0:3'--

    为了避免用户进行这个注入攻击系统,c#可以采用如下方法将参数过滤即可

    public static string ReplaceSQLChar(string str)
    {
    if (str == String.Empty)
    return String.Empty;
    str = str.Replace("'", "");
    str = str.Replace(";", "");
    str = str.Replace(",", "");
    str = str.Replace("?", "");
    str = str.Replace("<", "");
    str = str.Replace(">", "");
    str = str.Replace("(", "");
    str = str.Replace(")", "");
    str = str.Replace("@", "");
    str = str.Replace("=", "");
    str = str.Replace("+", "");
    str = str.Replace("*", "");
    str = str.Replace("&", "");
    str = str.Replace("#", "");
    str = str.Replace("%", "");
    str = str.Replace("$", "");

    //删除与数据库相关的词
    str = Regex.Replace(str, "select", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "insert", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "delete from", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "count", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "drop table", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "truncate", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "asc", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "mid", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "char", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "xp_cmdshell", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "exec master", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "net localgroup administrators", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "and", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "net user", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "or", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "net", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "-", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "delete", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "drop", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "script", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "update", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "and", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "chr", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "master", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "truncate", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "declare", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "mid", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "waitfor", "", RegexOptions.IgnoreCase);
    str = Regex.Replace(str, "delay", "", RegexOptions.IgnoreCase);
    return str;
    }

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  • 原文地址:https://www.cnblogs.com/a2502971/p/13410537.html
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