PHP Writeup - 35C3 CTF

In this challenge, we are given a PHP file with contents as shown below:

Challenge is running at: nc 35.242.207.13 1

So, we need to craft an input and send it in order to retrieve the flag.

Observations:

1. Our input will be unserialized.
2. There is a Class called "B" with a __destruct() method.
3. The __destruct() method will echo $flag.
4. $flag contains the contents of the file called flag.

We can send the serialized input as shown below to retrieve the flag:

Flag is: 35C3_php_is_fun_php_is_fun

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