Buuctf breakthrough diary --[mrctf2020]ez_ bypass1

The entry page is a little messy , Press view page source code , It is found that they are the same and relatively neat

I put something in F12 for you
include 'flag.php';
$flag='MRCTF{xxxxxxxxxxxxxxxxxxxxxxxxx}';
if(isset($_GET['gg'])&&isset($_GET['id'])) {
    $id=$_GET['id'];
    $gg=$_GET['gg'];
    if (md5($id) === md5($gg) && $id !== $gg) {
        echo 'You got the first step';
        if(isset($_POST['passwd'])) {
            $passwd=$_POST['passwd'];
            if (!is_numeric($passwd))
            {
                 if($passwd==1234567)
                 {
                     echo 'Good Job!';
                     highlight_file('flag.php');
                     die('By Retr_0');
                 }
                 else
                 {
                     echo "can you think twice??";
                 }
            }
            else{
                echo 'You can not get it !';
            }

        }
        else{
            die('only one way to get the flag');
        }
}
    else {
        echo "You are not a real hacker!";
    }
}
else{
    die('Please input first');
}
}Please input first

Code audit :

first if sentence :if(isset($_GET['gg'])&&isset($_GET['id']))

                    As long as the two parameters are not empty

the second if sentence :if (md5($id) === md5($gg) && $id !== $gg)

                    Simple ,md5 The encryption type is the same, the data is the same, and $id!==$gg, Bypass with empty array

Third if sentence :if(isset($_POST['passwd']))

                    post Ginseng passwd Not empty

The fourth one if sentence :if (!is_numeric($passwd))

                    passwd Not all numbers

The fifth one if sentence :if($passwd==1234567)

                    Because it can't be all numbers , But there is only == Judge , So there is a weak comparison bypass , Pass in 1234567aa

Meet the above five conditions and successfully get flag