~$ Digital Overdose CTF Official Writeup #1 - Outage
Posted on Oct. 11th, 2021.
This is the official developer writeup for the challenge 'Outage - The usual suspect' that was created for the Digital Overdose Autumn 2021 CTF.
The two other writeups published for this event are:
Challenge description and statistics
The text reads:
Digital Overdose has a website, and you can access some information about it without really needing to visit, a bit like a phone book of sorts.
Find the flag :)
Out of the 63 correct submissions (First blood by pidnull), this challenge was rated 100% by all contestants.
There is a quite a common meme nowadays when it comes to availability outages on the Internet, because it usually comes down to the same exact type of failure, most accurately summed up by:
As such, the title was already enough for most people to solve the challenge. If the player was unaware of this though, that is where the description comes in: What data can you get about a website, without visiting it. Bonus points if it is "Like an address book".
This question has a few simple answers:
- WHOIS data
- Page metadata
- DNS records
When considering DNS, one needs to think about what type of records could be used to store information. The obvious response would be TXT records:
Huh, what's that in line 15? It is a flag!
The flag is