Tags: frsc misc 


# PW API Stage 1
tags: misc | frsc

## Description

>Prof. Hackevoll always forgets his passwords. Thats why he wrote himself a password storage API...
He also used a self developed ticketing system.
It got so spammed that he doesn't use it anymore.
Maybe you can still find something useful in the [database dump](http://dl1.uni.hctf.fun/pwapi/tickets.zip) I found.

## Solution
The given dump is a zip that contains only the file `tickets.sql`, a big collection of SQL insert statements.
The first obvious attempt was to search in the file for the keyword "*flag*", but, as expected, the task is not so easy.

So looking at the sql statements the table *attachments* seems pretty interesting. It contains 60 rows formatted this way: `('id', 'ticket_id', 'attachment')`, where the attachment is a long hex value. Since trying to decode the first hex value result in a file, I decided to decode all af them, with a simple python script. To simplify the string processing in the string I just copied all the rows in a new file *input.txt*.
The script does some string processing to extract the id and the hex string of each files and convert it to a new binary file:

from binascii import unhexlify

with open('input.txt', 'r') as fd:
for line in fd:
index = line.split("(")[1].split(",")[0]
hex_str = line.split(" ")[2].split(")")[0].split("x")[1]

result = unhexlify(hex_str)
with open('files/file_' + index, 'wb') as new_file:

So after running it I can check out all the attachments, which turns out to be all memes images. The only different image is *file_30* and in fact it contains the flag:


*file_30* also contains some useful information for the task **PW API**.

Original writeup (https://github.com/draane/CTF/tree/master/PWN_CTF_2018/API%20stage%201).
swt02026Nov. 4, 2018, 8:30 a.m.

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