Hack.lu Writeups

2012 CTF by Fluxfingers

It was again a great moment of fun to participate to this year's CTF organised by Fluxfingers @ Hack.lu 2012

T-Shirt contest

This one is quite apart from the other challenges for several reasons:

• The challenge was actually printed on participants' t-shirts, as of last year
• Surprisingly enough, only 2 teams over the 290 who scored at least one challenge managed to solve it!! (none of the top 10, they were teams #50 and #83)
• The challenge was the only one not designed by Fluxfingers team but... by myself, with the help of Alex to design the actual T-Shirt

Still I played the ctf fairly, proof is that even my team (woyouyizhixiaomaol=我有一只小毛驴) didn't find the solution ;-)
I must admit, the challenge was easier for local people than for remote people, reason is that a list of words was written on the T-Shirt while online a patchwork of unrelated images was visible.
On first evening, as no one solved it yet, we added an extra hint in the challenge description.
On last morning, as no remote team managed to solve it, we also published a picture of the T-Shirt for remote teams. Apparently it didn't help...
Here is it:

28 - T-shirt
Same as local T-shirt challenge: https://ctf.fluxfingers.net/challenges/noclue.png 
Send your answers to (masked email on this wiki as it's too late and we hate spammers)
Hint: "It was in use sometime ago" #ctf #infosec 
Hint: https://ctf.fluxfingers.net/challenges/IMG_4924.JPG

Here is noclue.png:



Each element represents one word. Maybe you don't guess the exact right word for each of them, maybe not exactly in the right order, but it doesn't really matter as with a few words, it's enough to find the trick as we will see later.
So if we do the exercice we get something like:
RJ45? / unicode / crypta / assyria? / creatrix / ochra / chimaera / cumulate eucrite / jana antepono / condoleo / remissus / Πελασγοί=pelasgoi / articulo / cimex lectularius
First two seems to refer to known technologies while all the rest seems mostly latin words

Second image is the T-Shirt itself and there you get the exact word list:



So actual word list is:
utp cable unicode crypta assyrius creatrix ochra chimaera cumulate antepono condoleo remissus pelasga articulo cimex

I heard many teams trying really many things in all possible directions, sometimes wrong ones but sometimes right:

• crypta => cryptography?? and people tried many different things but it's wrong: what you have is not a ciphertext as it's somehow "meaningful", not garbage as ciphertexts usually are, and moreover the first hint says "It was in use sometime ago". Which *really* means people used this kind of message in the past, no pseudo-crypto I took of my hat.
• many saw that first three words are somehow separated from the rest, kind of header in front of a latin message
• someone interpreted it as those words are probably there to explain how to decode the latin message. And this is perfectly correct!
• but we are geeks and when we see utp cable unicode, our brain is too happy to know what they mean today while it seems hard to interpret! That's because thinking of the UTP you know and the Unicode you know is plain wrong :-) Remember the hint said it was in use *sometime ago*... not today and long ago they didn't know about Ethernet or UTF-8
• still in the funny interpretations, if you type the latin part in Google translate you get:

Assyrian vault creative ochra chimera cumulatively prefer EMPATHIZE *newly released article bug*
and they went googling for newly released vulnerability disclosures :-)