Plaidctf2014

plaidCTF 2014 - reeekeeeeee (web200)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance. Don't miss out on other write-ups at Eindbazen's site!
reeekeeeeee
Web (200 pts)
-------------
The Plague seems obsessed with internet memes, though we don't
yet know why. Perhaps there is a clue to what he's up to on this
server (epilepsy warning). If only you could break in....
Here is some of the source.

plaidCTF 2014 - rsa (for450)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
rsa
Forensics (450 pts)
--------------
Our archaeologists recovered a dusty and corrupted old hard drive used by
The Plague in his trips into the past. It contains a private key, but this
has long since been lost to bitrot. Can you recover the full key from the
little information we have recovered?

You can download the recovered information here.

plaidCTF 2014 - wheeeee (crypto375)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance. Don't miss out on other write-ups at Eindbazen's site!
wheeeee
Crypto (375 pts)
----------------
Although it seems like The Plague's messaging service is secure, 
there are bound to be bugs in any 20th century crypto system. 
We've recovered a version of the block cipher The Plague implemented. 
Use their online encryptor tool, at 54.82.75.29:8193, to break the 
cipher and figure out Plague's secret plans. NOTE: When the service 
sends you a hex-encoded string, respond with a hex-encoded string.
    

plaidCTF 2014 - bbos (for350)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
bbos
Forensics (350 pts)
-------------------

You have traveled back in time, but look, hunting  The Plague is tough.
You're really just going back to relax for a while  without having to
worry about all that nonsense. As you walk in the park  you stumble
across someone's BlackBerry. Wow, people still use  BlackBerry phones
(time travel gets so confusing)? You figure you should  return it to the
owner, but you have a hard time getting inside. Figure  out what's on
the phone, and maybe we'll be able to return it to the rightful owner.

BlackBerry was this fancy pager thing, right?

plaidCTF 2014 - graphs (crypto200)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

This challenge was about breaking a custom public key encryption system.

graphs
Cryptography (200 pts)
--------------
In this era, block ciphers hadn't even been invented. The Plague created this
system based on problems he knew to be NP hard, but there must be something you
can do to decode his messages.

We were given a python implementation of the system, the Plague’s public key and an encrypted message. The implementation includes encryption, decryption (given a private key) and key generation.

plaidCTF 2014 - g++ (re200)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance. Don't miss out on other write-ups at Eindbazen's site!
Although it seems like The Plague's projects are  open source, it's not
quite so simple to figure out what the source code  does. We believe
this project is supposed to print out secret information, but the KEY
variable in the Makefile has been lost. Find the key, build the
project, get us the information.

Oh noes, the key is gone!

plaidCTF 2014 - zfs (for400)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
zfs
Forensics (400 pts)
-------------------
The Plague is using state of the art systems for storing his data. 
Our operatives managed to steal a drive from one of his servers, 
but it seems like our haste may have led to some uber-corruption. 
Can you get the data off the drive to track down The Plague?

Sure we can. But where do we start?

plaidCTF 2014 - bronies (web800)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
bronies
Web (800 pts)
-------------------
We are trying to break into eXtreme Secure  Solutions, where The
Plague works as a system adminstrator.  We have found that their
internal company login page is at
http://portal.essolutions.largestctf.com/. Recon has also revealed
that  The Plague likes to browse this site during work hours:
http://54.196.225.30/ using the username ponyboy2004.  Remember, our
main target is to break into the company portal, *not* the pony site.

plaidCTF 2014 - doge_stege (for100)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

This challenge was about extracting a (not very well) hidden message out of an image file:

doge_stege
Forensics (100 pts)
--------------
You were startled to learn the The Plague has been behind many of the
most popular internet memes. We believe he hides information in these
funny pictures with steganography in order to broadcast his messages
through time without detection. Find the hidden message, stop the
signal.

Original doge_stege Image

Obvious Stego is Obvious

The first thing to do with every file you get from a CTF challenge is to run the file command on it:

% file doge_stege.png
doge_stege.png: PNG image data, 680 x 510, 8-bit colormap, non-interlaced

plaidCTF 2014 - rendezvous (misc250)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

This challenge was about establishing a connection to a hidden tor service which is rather picky in accepting connections. We were given the following description:

rendezvous
Misc (250 pts)
--------------
The Plague has a friend called Alice who has some secrets on a tor
service (http://6c4dm56aer6xn2h2.onion/). We think if we can talk to
her, we can learn some useful things about The Plague. Unfortunately
she will only rendezvous with "chandler" when he brings a cookie with
"beef" baked into it. Can you help us find her secret?

Getting Started

The first thing we did was of course trying to connect to the service. Whether using a tor to web gateway as for example onion.to or a local tor instance, the result was the same: no connection could be established. Using curl -v –socks5-hostname localhost:9050 http://6c4dm56aer6xn2h2.onion/ showed that curl didn’t even send the request, confirming that the problem is at the tor layer and not at the HTTP layer. Thus getting a tor connection to the hidden service is actually part of the challenge.

plaidCTF 2014 - ezhp (pwn200)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
ezhp
Pwnables (200 pts)
-------------------
Luckily when you travel back in time, you still get to use all your
knowledge from the present. With that knowledge in hand, breaking
into this service (at 54.81.149.239:9174) owned by The Plague
shouldn't be hard at all.

To set the picture, let’s identify the binary

:::bash
izsh@box:~$ file ezhp
ezhp: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.24,
BuildID[sha1]=0x5fa5bd76db306497b549ea3b0466cd9e9afa2705, stripped    

izsh@box:~$ readelf -l ezhp | grep STACK
    GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x4

plaidCTF 2014 - tiffany (re300)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
tiffany
Reversing (300 pts)
-------------------
We want to get access to a server used by The Plague. Maybe if you
can find out what key is accepted by this binary you can find out
where or when The Plague is...

Yay, a Linux x86_64 executable! Let’s run it and see what happens, because what could possibly go wrong when running a random binary off the internet?

$ ./tiffany
This may take a while...
.......
Please enter a string: TEST
....
Sorry, wrong.

Well, that took 3 seconds to initialize and 5 seconds per input string character. Sure seems to be doing a lot of stuff. Let’s load it into IDA to get a general idea.

plaidCTF 2014 - paris (re300)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
paris
Reversing (300 pts)
-------------------
This binary was found on some of our Windows machines. It's got The
Plague written all over it. What secrets are contained inside?

We are greeted by a Windows executable. Since I hate Windows and I can’t be arsed to pull up a Windows VM and debugger, I decided to solve this one statically. Time to load it into IDA.

plaidCTF 2014 - __nightmares__ (pwn375)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!
__nightmares__
Pwning (375 pts)
-------------------
The Plague is building an army of evil hackers, and they are starting
off by teaching them python with this simple service. Maybe if you
could get full access to this system, at 54.196.37.47:9990, you would
be able to find out more about The Plague's evil plans.

This server simply evaluates any Python expression provided - with an attempt at sandboxing it.

plaidCTF 2014 - freya (misc250)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

This challenge is part of the misc category:

freya
Misc (200 pts)
-------------------
We've traveled back far, but this protocol looks familiar...
Our reconnaissance team did a great job, they got us a data capture
from the currently running systems and a private key
from the server (shell.woo.pctf which resolves to 54.226.73.167).
Take  a look at the traffic our reconnaissance team picked up, and see if you
can get access to The Plague's server, at 54.226.73.167.

with the following four files:

  • freya.pcapng
  • freya_cert.pem
  • freya_priv.pem
  • password

The task is pretty simple - somehow get access to shell.woo.pctf, probably by using ssh.

plaidCTF 2014 - curlcore (for250)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
Don't miss out on other write-ups at Eindbazen's site!

Last week we played plaidCTF with Eindbazen under the name 0xffa (can you figure out why that name?). Write-ups are mandatory in the rules, so let’s start with an easy one :-)

curlcore
Forensics (250 pts)
-------------------
We managed to grab a memory dump off of The Plague's computer while
he was making a secure download. We think he may have been looking
for new places to hide the Prime Factorizer. Can you figure out what
messages were sent through his computer?

For this challenge, you get 3 files:

  • capture (a network capture)
  • corefile (a memory dump)
  • coremaps (the process’s memory map)

and the shell script which helped generating those files

:::bash
#/bin/sh

sudo rm /tmp/capture 2>/dev/null
sudo dumpcap -i eth0 -w /tmp/capture &
DUMPCAPPID=$!

sleep 1
OUTPUT="`/usr/bin/env -i /bin/dash -c 'ulimit -c unlimited; curl -k https://curlcore.local.plaidctf.com/flag.html & PID=$!;     sleep 5; printf "generate-core-file\ninfo proc mappings\ndetach\n" | sudo gdb attach $PID; wait'`"
sleep 1

sudo kill -INT $DUMPCAPPID
wait

sudo chown `whoami` /tmp/capture

echo "$OUTPUT"

sudo mv "`echo "$OUTPUT" | grep -o 'Saved corefile .*$' | cut -c 16-`" /tmp/corefile
sudo chown `whoami` /tmp/corefile


echo "$OUTPUT" | awk '/Mapped address spaces/,/(gdb)/' | grep -v '(gdb)' > /tmp/coremaps

rm /tmp/curlcore.tgz 2>/dev/null
tar czf /tmp/curlcore.tgz `grep -o ' /.*$' /tmp/coremaps | sort -us | tr '\n' ' '` /tmp/corefile /tmp/coremaps /tmp/capture     "$0"

Since we have a network capture of the https download, we need to find a way to decrypt the SSL communication…

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