2019 PlaidCTF write up

題目先屯一份打完取證回來慢慢的復現~~

Reverse

i can count - 50pts

Let's do this together. You do know how to count, don't you?

The .Wat ness - 250pts

The .Wat ness is open for testing!

http://watness.pwni.ng:7744/

When it came out in 2016, the Witness impressed with its ability to gradually teach new players the rules of the game by simply having them play it. With the .Wat ness, we take this just a small step further.

Plaid Party Planning III - 500pts

This year, we're having another party. We managed to come to a consensus to have Indian food, but I can't figure out where everyone should sit. Can you help us make sure the dinner goes off without a hitch?

Plaid Party Planning III 2 - 500pts

This binary has a fix for an unintentional solution. Let's keep the party going.

NOTE: We have pushed an updated binary. This update fixes a bug in the check function and should hopefully make the check function easier to understand. The diff with the binary below should be minimal. Apologies.

The previous Plaid Party Planning III 2 binary.

Hint: Admin contact
Please message strikeskids on IRC (#pctf on freenode) if you have a solution that should pass the check, but does not give a valid flag.

big maffs - 250 pts

Do you have enough memory? big_maffs

Crypto

SPlaid Cypress - 600pts

I came up with this carbon-neutral cryptosystem and hid my secrets in the forest. Can you help them find their way out?

R u SAd? - 150pts

Tears dripped from my face as I stood over the bathroom sink. Exposed again! The tears melted into thoughts, and an idea formed in my head. This will surely keep my secrets safe, once and for all. I crept back to my computer and began to type.

Horst - 200pts

They say 3 rounds is provably secure, right? Download

Misc

docker - 10pts

docker pull whowouldeverguessthis/public

Everland - 250pts

In a darkened land, a hero must fight for their flag! Source

running at everland.pwni.ng:7772

can you guess me - 100pts

Here's the source to a guessing game: here

You can access the server at

nc canyouguessme.pwni.ng 12349

Space Saver - 100pts

we couldn't think of anything cute so here you go

graffiti - 333pts

QUAAAAAKE

In lieu of a description, please watch this video. Alternate link

A Whaley Good Joke - 150pts

You'll have a whale of a time with this one! I couldn't decide what I wanted the flag to be so I alternated adding and removing stuff in waves until I got something that looked good. Can you dive right in and tell me what was so punny?

Project Eulernt - 200pts

Guys, guys, don’t fight. I’m sure we’ll be able to come up with something roughly equal.

source

eulernt.pwni.ng:5555

NOTE: We originally uploaded the wrong version. It is still available here if you really want it: wrong version.

Pwn

CPP - 150pts

C++ is hard.

cppp.pwni.ng 4444

binary, libc

Hint: Additional port
The service is now also running on cppp.pwni.ng:7777 for those ISPs that block egress to port 4444.

SPlaid Birch - 300pts

I make sure never to use

scanf("%s")
when doing competitive programming so that my solutions don't have buffer overflows. But writing algorithms is hard.

files

splaid-birch.pwni.ng:17579