NaSCon'23

In this challenge, we have to bypass two preg_match functions to get the flag. The Given Code <?php #read flag.txt highlight_file(__FILE__); $code = $_GET['cmd']; $blocked_functions = '/(exec|shell_exec|system|`)/i'; if (preg_match($blocked_functions, $code)) { die("Hacking attempt detected"); } else { $blocked_functions = "/flag/i"; if (preg_match($blocked_functions, $code)) { die("Hacking attempt detected"); } else{ eval(urldecode($code)); } } ?> Initially, It highlights the code file. Then it stores the ‘cmd’ get parameter value in code variable, it blocks all the functions through which we can execute the shell commands....