Posts Tagged ‘day 1’

HACKvent 2015: Day 1

09 Dec 2015
CTF: Hackvent 2015
Link to challenge:
Date Completed: 09 December 2015



I decode the string above using a Vigenere Cipher solver with the key ‘geek‘ (deduced from frequency analysis).

The message I get is:

The message is pretty clear. First spot I check as a webmaster is /robots.txt (psss go check my websites robots.txt :p). I find 1 disallowed resource which is: /MeMyselfAndI-surfingInTheSky/hacker.jpg

I visit this webpage in my browser and find the picture Santa was hiding, here it is:
Santas Hidden Picture

Following Santa’s clues, I use Google reverse image search to find other images like this on the web.
I find one website with a similar image, namely at:

This is what the webpage looks like:
Hacking-Lab Club Webpage

Drat! We are too late, luckily cache is a thing.
You can either check WayBackMachine or Google cache to find a previous state for the webpage.
We inspect the source of the website in Google cache and discover a reference to: /work.jpg
Unfortunately that image is not on the live website but work.png was! (Finding this was just guesswork based on the format of the ‘too late’ Christmas ball).

This is what work.png looks like:

Day 1 Solution QR Code

We scan it to get our flag:  HV15-Tz9K-4JIJ-EowK-oXP1-NUYL

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Posted in Hackvent 2015


Advent Of Code: Day 1

02 Dec 2015
CTF: Advent Of Code
Link to challenge:
Date Completed: 01/12/2015

The Challenge



Before part 2 of the problem was revealed I decided to tackle the problem using the command line. I cam up with the following command:

We echo the input and remove the ) symbol which leaves only ( and we use wc to count the number of  ( symbols which tells us how many times we went to a higher floor. We then subtract his number from the number of times we went to a lower floor (using bash arithmetic) which gives us our answer.

Part 2 of the problem would be annoying to do on the command line so I decided to write a quick python script to solve it. The solution also solves the first part of the problem (lol).


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Posted in Advent Of Code